WorldWideScience

Sample records for internal flow effects

  1. Flow effects due to valve and piston motion in an internal combustion engine exhaust port

    International Nuclear Information System (INIS)

    Semlitsch, Bernhard; Wang, Yue; Mihăescu, Mihai

    2015-01-01

    Highlights: • Flow regime identification depending on the valve lift during the exhaust stroke. • Analysis of the valve motion effect onto the flow development in the exhaust port. • Physical interpretation of commonly used discharge and flow coefficient formulations. • Illustration of flow effects in junction regions with pulsatile flow. - Abstract: Performance optimization regarding e.g. exhaust valve strategies in an internal combustion engine is often performed based on one-dimensional simulation investigation. Commonly, a discharge coefficient is used to describe the flow behavior in complex geometries, such as the exhaust port. This discharge coefficient for an exhaust port is obtained by laboratory experiments at fixed valve lifts, room temperatures, and low total pressure drops. The present study investigates the consequences of the valve and piston motion onto the energy losses and the discharge coefficient. Therefore, Large Eddy Simulations are performed in a realistic internal combustion geometry using three different modeling strategies, i.e. fixed valve lift and fixed piston, moving piston and fixed valve lift, and moving piston and moving valve, to estimate the energy losses. The differences in the flow field development with the different modeling approaches is delineated and the dynamic effects onto the primary quantities, e.g. discharge coefficient, are quantified. Considering the motion of piston and valves leads to negative total pressure losses during the exhaust cycle, which cannot be observed at fixed valve lifts. Additionally, the induced flow structures develop differently when valve motion is taken into consideration, which leads to a significant disparity of mass flow rates evolving through the two individual valve ports. However, accounting for piston motion and limited valve motion, leads to a minor discharge coefficient alteration of about one to two percent

  2. Effect of internal flow and evaporation on hydrogel assembly process at droplet interface

    Science.gov (United States)

    Kang, Giho; Seong, Baekhoon; Gim, Yeonghyeon; Ko, Han Seo; Byun, Doyoung

    2017-11-01

    Recently, controlling the behavior of nanoparticles inside liquid droplet has been widely studied. There have been many reports about the mechanism of the nanoparticles assembly and fabrication of a thin film on a substrate. However, the assembly mechanism at a liquid-air interface has not been clearly understood to form polymer chains into films. Herein, we investigated the role of internal flow on the thin film assembly process at the interface of the hydrogel droplet. The internal fluid flow during the formation of the hydrogel film was visualized systematically using micro-PIV (Particle image velocimetry) technique at various temperatures. We show that the buoyancy effect and convection flow induced by heat can affect the film morphology and its mechanical characteristics. Due to the accelerated fluid flow inside the droplet and evaporation flux, densely assembled hydrogel film was able to be formed. Film strength was increased 24% with temperature increase from 40 to 80 degrees Celsius. We expect our investigations could be applied to many applications such as self-assembly of planar structures at the interface in coating and printing process. The support from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2015R1A2A1A05001829) is acknowledged.

  3. Ventilation and internal structure effects on naturally induced flows in a static aircraft wing

    International Nuclear Information System (INIS)

    Moore, Daithi; Newport, David; Egan, Vanessa; Lacarac, Vesna

    2012-01-01

    The ventilation performance within an aircraft wing leading edge is investigated for a number of enclosure and ventilation configurations. The natural convection regime present is found to be highly sensitive to enclosure conditions, particularly the introduction of a partition. The presence of a partition reduced the overall heat exhausted from the cavity by up to 60%. The optimum ventilation strategy is also changed from a forward biased vent orientation (found for the unpartitioned case), to one where both the rear and front vents within the enclosure had the same open area. Cylinder plume effects dominate within the enclosure and were the main driver of the convective regime, with steady-state enclosure conditions highly dependent upon cylinder placement and plume orientation. An externally heated enclosure with internal heat source, combined with ventilation and an internal structure produced a complex natural convection regime which is sensitive to enclosure conditions. Hence an adequate knowledge of such conditions is necessary in order to fully appreciate the convective regime. - Highlights: → Optimum ventilation strategy changed between unpartitioned and partitioned cases. → Flow path and plume orientation are important to consider when analysing ventilation. → Bleed duct placement significantly alters flow path and temperature distribution. → Enclosure partitioning reduced heat exhaustion by 60%.

  4. Effect of bidirectional internal flow on fluid–structure interaction dynamics of conveying marine riser model subject to shear current

    Directory of Open Access Journals (Sweden)

    Zheng-Shou Chen

    2012-03-01

    Full Text Available This article presents a numerical investigation concerning the effect of two kinds of axially progressing internal flows (namely, upward and downward on fluid–structure interaction (FSI dynamics about a marine riser model which is subject to external shear current. The CAE technology behind the current research is a proposed FSI solution, which combines structural analysis software with CFD technology together. Efficiency validation for the CFD software was carried out first. It has been proved that the result from numerical simulations agrees well with the observation from relating model test cases in which the fluidity of internal flow is ignorable. After verifying the numerical code accuracy, simulations are conducted to study the vibration response that attributes to the internal progressive flow. It is found that the existence of internal flow does play an important role in determining the vibration mode (/dominant frequency and the magnitude of instantaneous vibration amplitude. Since asymmetric curvature along the riser span emerges in the case of external shear current, the centrifugal and Coriolis accelerations owing to up- and downward internal progressive flows play different roles in determining the fluid–structure interaction response. The discrepancy between them becomes distinct, when the velocity ratio of internal flow against external shear current is relatively high.

  5. Effect of air flow, panel curvature, and internal pressurization on field-incidence transmission loss

    Science.gov (United States)

    Koval, L. R.

    1976-01-01

    In the context of sound transmission through aircraft fuselage panels, equations for the field-incidence transmission loss (TL) of a single-walled panel are derived that include the effects of external air flow, panel curvature, and internal fuselage pressurization. Flow is shown to provide a modest increase in TL that is uniform with frequency up to the critical frequency. The increase is about 2 dB at Mach number M = 0.5, and about 3.5 dB at M = 1. Above the critical frequency where TL is damping controlled, the increase can be slightly larger at certain frequencies. Curvature is found to stiffen the panel, thereby increasing the TL at low frequencies, but also to introduce a dip at the 'ring frequency' of a full cylinder having the same radius as the panel. Pressurization appears to produce a slight decrease in TL throughout the frequency range, and also slightly shifts the dips at the critical frequency and at the ring frequency.

  6. Effect of fuel temperature on the methanol spray and nozzle internal flow

    International Nuclear Information System (INIS)

    Chen, Zhifang; Yao, Anren; Yao, Chunde; Yin, Zenghui; Xu, Han; Geng, Peilin; Dou, Zhancheng; Hu, Jiangtao; Wu, Taoyang; Ma, Ming

    2017-01-01

    Highlights: • Cavitation region increases with the increasing of methanol temperature. • The nozzle exit velocity increases with the increasing of methanol temperature. • The discharge coefficient decreases with the increasing of methanol temperature. • Droplet SMD reduces when methanol temperature increases measured by PDPA system. • Droplet velocity has the maximum value when methanol temperature is 60 °C. - Abstract: The increasing of fuel temperature can reduce the droplet size and have an advantage of improving spray atomization, while investigations of the effect of temperature on the methanol injector internal flow and external spray is rare. Firstly, a detailed three dimensional numerical simulations of nozzle internal flow have been conducted to probe into the cavitation in methanol injector nozzles, and then an experimental study has been carried out to investigate the droplet size and velocity of methanol spray at various temperatures using the Phase Doppler Particle Analyzer (PDPA) detecting system. And results show that the region of cavitations in nozzle orifice enlarges as methanol temperature and injection pressure increases, and the temperature for 'super-cavitation' occurring decreases gradually with the increasing of injection pressure. Moreover, the nozzle exit velocity, discharge coefficient and cavitations number were also analyzed. However, the discharge coefficient reduces nearly equal under various pressure when the methanol temperature is higher than 60 °C. In addition, the Sauter Mean Diameter (SMD) and velocity of methanol droplet were also analyzed, and found that the droplet velocity reaches the maximum value when the methanol temperature is 60 °C.

  7. Flow effects due to pulsation in an internal combustion engine exhaust port

    International Nuclear Information System (INIS)

    Semlitsch, Bernhard; Wang, Yue; Mihăescu, Mihai

    2014-01-01

    Highlights: • Using POD analysis to identify large coherent flow structures in a complex geometry. • Flow field alters significant for constant and pulsating boundary conditions. • The discharge coefficient of the exhaust port decreases 2% with flow pulsation. • Pulsation causes a pumping mechanism due to a phase shift of pressure and momentum. - Abstract: In an internal combustion engine, the residual energy remaining after combustion in the exhaust gasses can be partially recovered by a downstream arranged device. The exhaust port represents the passage guiding the exhaust gasses from the combustion chamber to the energy recovering device, e.g. a turbocharger. Thus, energy losses in the course of transmission shall be reduced as much as possible. However, in one-dimensional engine models used for engine design, the exhaust port is reduced to its discharge coefficient, which is commonly measured under constant inflow conditions neglecting engine-like flow pulsation. In this present study, the influence of different boundary conditions on the energy losses and flow development during the exhaust stroke are analyzed numerically regarding two cases, i.e. using simple constant and pulsating boundary conditions. The compressible flow in an exhaust port geometry of a truck engine is investigated using three-dimensional Large Eddy Simulations (LES). The results contrast the importance of applying engine-like boundary conditions in order to estimate accurately the flow induced losses and the discharge coefficient of the exhaust port. The instantaneous flow field alters significantly when pulsating boundary conditions are applied. Thus, the induced losses by the unsteady flow motion and the secondary flow motion are increased with inflow pulsations. The discharge coefficient decreased about 2% with flow pulsation. A modal flow decomposition method, i.e. Proper Orthogonal Decomposition (POD), is used to analyze the coherent structures induced with the particular

  8. 2007 Estimated International Energy Flows

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C A; Belles, R D; Simon, A J

    2011-03-10

    An energy flow chart or 'atlas' for 136 countries has been constructed from data maintained by the International Energy Agency (IEA) and estimates of energy use patterns for the year 2007. Approximately 490 exajoules (460 quadrillion BTU) of primary energy are used in aggregate by these countries each year. While the basic structure of the energy system is consistent from country to country, patterns of resource use and consumption vary. Energy can be visualized as it flows from resources (i.e. coal, petroleum, natural gas) through transformations such as electricity generation to end uses (i.e. residential, commercial, industrial, transportation). These flow patterns are visualized in this atlas of 136 country-level energy flow charts.

  9. Internal wave structures in abyssal cataract flows

    Science.gov (United States)

    Makarenko, Nikolay; Liapidevskii, Valery; Morozov, Eugene; Tarakanov, Roman

    2014-05-01

    We discuss some theoretical approaches, experimental results and field data concerning wave phenomena in ocean near-bottom stratified flows. Such strong flows of cold water form everywhere in the Atlantic abyssal channels, and these currents play significant role in the global water exchange. Most interesting wave structures arise in a powerful cataract flows near orographic obstacles which disturb gravity currents by forced lee waves, attached hydraulic jumps, mixing layers etc. All these effects were observed by the authors in the Romanche and Chain fracture zones of Atlantic Ocean during recent cruises of the R/V Akademik Ioffe and R/V Akademik Sergei Vavilov (Morozov et al., Dokl. Earth Sci., 2012, 446(2)). In a general way, deep-water cataract flows down the slope are similar to the stratified flows examined in laboratory experiments. Strong mixing in the sill region leads to the splitting of the gravity current into the layers having the fluids with different densities. Another peculiarity is the presence of critical layers in shear flows sustained over the sill. In the case under consideration, this critical level separates the flow of near-bottom cold water from opposite overflow. In accordance with known theoretical models and laboratory measurements, the critical layer can absorb and reflect internal waves generated by the topography, so the upward propagation of these perturbations is blocked from above. High velocity gradients were registered downstream in the vicinity of cataract and it indicates the existence of developed wave structures beyond the sill formed by intense internal waves. This work was supported by RFBR (grants No 12-01-00671-a, 12-08-10001-k and 13-08-10001-k).

  10. Analysis of flow and LDL concentration polarization in siphon of internal carotid artery: Non-Newtonian effects.

    Science.gov (United States)

    Sharifi, Alireza; Niazmand, Hamid

    2015-10-01

    Carotid siphon is known as one of the risky sites among the human intracranial arteries, which is prone to formation of atherosclerotic lesions. Indeed, scientists believe that accumulation of low density lipoprotein (LDL) inside the lumen is the major cause of atherosclerosis. To this aim, three types of internal carotid artery (ICA) siphon have been constructed to examine variations of hemodynamic parameters in different regions of the arteries. Providing real physiological conditions, blood considered as non-Newtonian fluid and real velocity and pressure waveforms have been employed as flow boundary conditions. Moreover, to have a better estimation of risky sites, the accumulation of LDL particles has been considered, which has been usually ignored in previous relevant studies. Governing equations have been discretized and solved via open source OpenFOAM software. A new solver has been built to meet essential parameters related to the flow and mass transfer phenomena. In contrast to the common belief regarding negligible effect of blood non-Newtonian behavior inside large arteries, current study suggests that the non-Newtonian blood behavior is notable, especially on the velocity field of the U-type model. In addition, it is concluded that neglecting non-Newtonian effects underestimates the LDL accumulation up to 3% in the U-type model at the inner side of both its bends. However, in the V and C type models, non-Newtonian effects become relatively small. Results also emphasize that the outer part of the second bend at the downstream is also at risk similar to the inner part of the carotid bends. Furthermore, from findings it can be implied that the risky sites strongly depend on the ICA shape since the extension of the risky sites are relatively larger for the V-type model, while the LDL concentrations are higher for the C-type model. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Internal and external axial corner flows

    Science.gov (United States)

    Kutler, P.; Shankar, V.; Anderson, D. A.; Sorenson, R. L.

    1975-01-01

    The inviscid, internal, and external axial corner flows generated by two intersecting wedges traveling supersonically are obtained by use of a second-order shock-capturing, finite-difference approach. The governing equations are solved iteratively in conical coordinates to yield the complicated wave structure of the internal corner and the simple peripheral shock of the external corner. The numerical results for the internal flows compare favorably with existing experimental data.

  12. Effects of cavity size on the control of transonic internal flow around a biconvex circular arc airfoil

    Science.gov (United States)

    Rahman, M. Mostaqur; Hasan, A. B. M. Toufique; Rabbi, M. S.

    2017-06-01

    In transonic flow conditions, self-sustained shock wave oscillation on biconvex airfoils is initiated by the complex shock wave boundary layer interaction which is frequently observed in several modern internal aeronautical applications such as inturbine cascades, compressor blades, butterfly valves, fans, nozzles, diffusers and so on. Shock wave boundary layer interaction often generates serious problems such as unsteady boundary layer separation, self-excited shock waveoscillation with large pressure fluctuations, buffeting excitations, aeroacoustic noise, nonsynchronous vibration, high cycle fatigue failure and intense drag rise. Recently, the control of the self-excited shock oscillation around an airfoil using passive control techniques is getting intense interest. Among the passive means, control using open cavity has found promising. In this study, the effect of cavity size on the control of self-sustained shock oscillation was investigated numerically. The present computations are validated with available experimental results. The results showed that the average root mean square (RMS) of pressure oscillation around the airfoil with open cavity has reduced significantly when compared to airfoil without cavity (clean airfoil).

  13. Thermodilution-determined Internal Jugular Venous Flow

    DEFF Research Database (Denmark)

    Rasmussen, Peter; Widmer, Mario; Hilty, Matthias P

    2017-01-01

    PURPOSE: Cerebral blood flow (CBF) increases ~20% during whole body exercise although a Kety-Schmidt-determined CBF is reported to remain stable; a discrepancy that could reflect evaluation of arterial vs. internal jugular venous (IJV) flow and/or that CBF is influenced by posture. Here we test...

  14. Effects of objectifying gaze on female cognitive performance: The role of flow experience and internalization of beauty ideals.

    Science.gov (United States)

    Guizzo, Francesca; Cadinu, Mara

    2017-06-01

    Although previous research has demonstrated that objectification impairs female cognitive performance, no research to date has investigated the mechanisms underlying such decrement. Therefore, we tested the role of flow experience as one mechanism leading to performance decrement under sexual objectification. Gaze gender was manipulated by having male versus female experimenters take body pictures of female participants (N = 107) who then performed a Sustained Attention to Response Task. As predicted, a moderated mediation model showed that under male versus female gaze, higher internalization of beauty ideals was associated with lower flow, which in turn decreased performance. The implications of these results are discussed in relation to objectification theory and strategies to prevent sexually objectifying experiences. © 2016 The British Psychological Society.

  15. Synergistic effects of the safety factor and shear flows on development of internal transport barriers in reversed shear plasmas

    International Nuclear Information System (INIS)

    Wang, A.K.; Dong, J.Q.; Qu, W.X.; Qiu, X.M.

    2002-01-01

    A new suppression mechanism of turbulent transport, characteristic of the synergism between safety factor and shear flows, is proposed to explain the internal transport barriers (ITBs) observed in neutral-beam-heated tokamak discharges with reversed magnetic shear. It is shown that the evolution of turbulent transport with the strength of the suppression mechanism reproduces the basic features of the formation and development of ITBs observed in experiments. In addition, the present analyses predict the possibility of global ion and electron heat transport barriers

  16. The effect of air flow, panel curvature, and internal pressurization on field-incidence transmission loss. [acoustic propagation through aircraft fuselage

    Science.gov (United States)

    Koval, L. R.

    1975-01-01

    In the context of sound transmission through aircraft fuselage panels, equations for the field-incidence transmission loss (TL) of a single-walled panel are derived that include the effects of external air flow, panel curvature, and internal fuselage pressurization. These effects are incorporated into the classical equations for the TL of single panels, and the resulting double integral for field-incidence TL is numerically evaluated for a specific set of parameters.

  17. Boundary element method for internal axisymmetric flow

    Directory of Open Access Journals (Sweden)

    Gokhman Alexander

    1999-01-01

    Full Text Available We present an accurate fast method for the computation of potential internal axisymmetric flow based on the boundary element technique. We prove that the computed velocity field asymptotically satisfies reasonable boundary conditions at infinity for various types of inlet/exit. Computation of internal axisymmetric potential flow is an essential ingredient in the three-dimensional problem of computation of velocity fields in turbomachines. We include the results of a practical application of the method to the computation of flow in turbomachines of Kaplan and Francis types.

  18. Mathematics of flexible risers including pressure and internal flow affects

    Energy Technology Data Exchange (ETDEWEB)

    Seyed, F.B. (John Brown Engineers and Constructors Ltd., London (GB)); Patel, M.H. (University Coll., London (GB). Dept. of Mechanical Engineering)

    1992-01-01

    Derivations are presented for calculation of pressure and internal flow induced forces on flexible risers and other curved pipes using a mathematically rigorous approach. Approximate and exact methods are presented for calculation of pressure forces on straight and curved pipes in two dimensions. The mathematical identity of these equations with those for effective tension is illustrated. The force arising from the flow of an internal fluid of constant density is then calculated and combined with those for pressure forces in derivation of the catenary equations including pressure and internal flow terms. It is shown that internal flow contributes a new term to the expression for effective tension. These governing equations are then reduced for the specific cases of simple catenary, steep-S, lazy-S, steep-wave and lazy-wave risers. In each case, the solution method has been presented and the governing equilibrium and geometric compatability conditions cited. (author).

  19. Performance and internal flow characteristics of a cross-flow turbine by guide vane angle

    International Nuclear Information System (INIS)

    Chen, Z M; Choi, Y D

    2013-01-01

    This study attempts to investigate the performance and internal flow characteristics of a cross-flow turbine by guide vane angle. In order to improve the performance of a cross flow turbine, the paper presents a numerical investigation of the turbine with air supply and discusses the influence of variable guide vane angle on the internal flow. A newly developed air supply from air suction Hole is adopted. To investigate the performance and internal flow of the cross-flow turbine, the CFD software based on the two-phase flow model is utilized. The numerical grids are made in two-dimensional geometry in order to shorten the time of two-phase calculations. Then a series of CFD analysis has been conducted in the range of different guide vane angle. Moreover, local output power is divided at different stages and the effect of air layer in each stage is examined

  20. Effects of Rotation at Different Channel Orientations on the Flow Field inside a Trailing Edge Internal Cooling Channel

    Directory of Open Access Journals (Sweden)

    Matteo Pascotto

    2013-01-01

    Full Text Available The flow field inside a cooling channel for the trailing edge of gas turbine blades has been numerically investigated with the aim to highlight the effects of channel rotation and orientation. A commercial 3D RANS solver including a SST turbulence model has been used to compute the isothermal steady air flow inside both static and rotating passages. Simulations were performed at a Reynolds number equal to 20000, a rotation number (Ro of 0, 0.23, and 0.46, and channel orientations of γ=0∘, 22.5°, and 45°, extending previous results towards new engine-like working conditions. The numerical results have been carefully validated against experimental data obtained by the same authors for conditions γ=0∘ and Ro = 0, 0.23. Rotation effects are shown to alter significantly the flow field inside both inlet and trailing edge regions. These effects are attenuated by an increase of the channel orientation from γ=0∘ to 45°.

  1. Piezoelectric Energy Harvesting in Internal Fluid Flow

    Directory of Open Access Journals (Sweden)

    Hyeong Jae Lee

    2015-10-01

    Full Text Available We consider piezoelectric flow energy harvesting in an internal flow environment with the ultimate goal powering systems such as sensors in deep oil well applications. Fluid motion is coupled to structural vibration via a cantilever beam placed in a converging-diverging flow channel. Two designs were considered for the electromechanical coupling: first; the cantilever itself is a piezoelectric bimorph; second; the cantilever is mounted on a pair of flextensional actuators. We experimentally investigated varying the geometry of the flow passage and the flow rate. Experimental results revealed that the power generated from both designs was similar; producing as much as 20 mW at a flow rate of 20 L/min. The bimorph designs were prone to failure at the extremes of flow rates tested. Finite element analysis (FEA showed fatigue failure was imminent due to stress concentrations near the bimorph’s clamped region; and that robustness could be improved with a stepped-joint mounting design. A similar FEA model showed the flextensional-based harvester had a resonant frequency of around 375 Hz and an electromechanical coupling of 0.23 between the cantilever and flextensional actuators in a vacuum. These values; along with the power levels demonstrated; are significant steps toward building a system design that can eventually deliver power in the Watts range to devices down within a well.

  2. Piezoelectric energy harvesting in internal fluid flow.

    Science.gov (United States)

    Lee, Hyeong Jae; Sherrit, Stewart; Tosi, Luis Phillipe; Walkemeyer, Phillip; Colonius, Tim

    2015-10-14

    We consider piezoelectric flow energy harvesting in an internal flow environment with the ultimate goal powering systems such as sensors in deep oil well applications. Fluid motion is coupled to structural vibration via a cantilever beam placed in a converging-diverging flow channel. Two designs were considered for the electromechanical coupling: first; the cantilever itself is a piezoelectric bimorph; second; the cantilever is mounted on a pair of flextensional actuators. We experimentally investigated varying the geometry of the flow passage and the flow rate. Experimental results revealed that the power generated from both designs was similar; producing as much as 20 mW at a flow rate of 20 L/min. The bimorph designs were prone to failure at the extremes of flow rates tested. Finite element analysis (FEA) showed fatigue failure was imminent due to stress concentrations near the bimorph's clamped region; and that robustness could be improved with a stepped-joint mounting design. A similar FEA model showed the flextensional-based harvester had a resonant frequency of around 375 Hz and an electromechanical coupling of 0.23 between the cantilever and flextensional actuators in a vacuum. These values; along with the power levels demonstrated; are significant steps toward building a system design that can eventually deliver power in the Watts range to devices down within a well.

  3. International Workshop on Traffic and Granular Flow

    CERN Document Server

    Herrmann, Hans; Schreckenberg, Michael; Wolf, Dietrich; Social, Traffic and Granular Dynamics

    2000-01-01

    "Are there common phenomena and laws in the dynamic behavior of granular materials, traffic, and socio-economic systems?" The answers given at the international workshop "Traffic and Granular Flow '99" are presented in this volume. From a physical standpoint, all these systems can be treated as (self)-driven many-particle systems with strong fluctuations, showing multistability, phase transitions, non-linear waves, etc. The great interest in these systems is due to several unexpected new discoveries and their practical relevance for solving some fundamental problems of today's societies. This includes intelligent measures for traffic flow optimization and methods from "econophysics" for stabilizing (stock) markets.

  4. International Trade Modelling Using Open Flow Networks: A Flow-Distance Based Analysis.

    Science.gov (United States)

    Shen, Bin; Zhang, Jiang; Li, Yixiao; Zheng, Qiuhua; Li, Xingsen

    2015-01-01

    This paper models and analyzes international trade flows using open flow networks (OFNs) with the approaches of flow distances, which provide a novel perspective and effective tools for the study of international trade. We discuss the establishment of OFNs of international trade from two coupled viewpoints: the viewpoint of trading commodity flow and that of money flow. Based on the novel model with flow distance approaches, meaningful insights are gained. First, by introducing the concepts of trade trophic levels and niches, countries' roles and positions in the global supply chains (or value-added chains) can be evaluated quantitatively. We find that the distributions of trading "trophic levels" have the similar clustering pattern for different types of commodities, and summarize some regularities between money flow and commodity flow viewpoints. Second, we find that active and competitive countries trade a wide spectrum of products, while inactive and underdeveloped countries trade a limited variety of products. Besides, some abnormal countries import many types of goods, which the vast majority of countries do not need to import. Third, harmonic node centrality is proposed and we find the phenomenon of centrality stratification. All the results illustrate the usefulness of the model of OFNs with its network approaches for investigating international trade flows.

  5. RISKS AND CONTRADICTORY OF INTERNATIONAL CAPITAL FLOWS IN BANKING

    Directory of Open Access Journals (Sweden)

    V. Shevchenko

    2014-03-01

    Full Text Available The content of the international capital flows are studied, its contradictor influence on global and national processes. Some theoretical approaches on contradictory impact of capital flows. The major risks of international capital flows in banking sector are determined including financial, currency, assets value decrease, credit rating etc. The capital flows reversal flows are explained. The modern changes of international capital flows to banking sector of Ukraine are discovered.

  6. Free Vibrations of Uniform Pipes Made From Composite Materials at an Internal Flow Under Effect of Additional Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Nawal H. Al – Raheimy

    2016-09-01

    Full Text Available In this paper the approximate method of Raleigh method can be used to study the effect of additional boundary conditions (clamped – free & clamped – clamped on the free transverse vibrations of uniform pipes which have length, L (1m , inner radius, "Ri" (1cm & thickness, "t" (1mm made from composite materials, where the resin of unsaturated polyester represented the matrix material reinforced by aligned (E-fibers glass in the first case and used aligned fiber (Kevlar-49 in the second case. The length of fibers is in the two types, the first type is long fibers (continuous and the second is short fibers (discontinuous for different length all at volume fraction of fibers, "f" (0.15 & 0.25. At any construction of the pipe in composite material the natural frequency decreased when the velocity of flow increased from zero to critical velocity also can be observed the pipe at clamped – clamped boundary conditions predicts natural frequency & critical velocity greater than that pipe at clamped – free. The natural frequency and critical velocity increase with increasing volume fraction and length of discontinuous fiber. The value of natural frequency for pipes which have continuous fibers is constant at certain velocity of flow while are variable in pipes which have discontinuous fibers according to ratio between length of short fiber to critical length of discontinuous fiber whereas the natural frequency increase with increasing this ratio. Finally the pipes with Kevlar fiber have high critical velocity and natural frequency compare with pipes for fiber glass.

  7. Measuring Gravity in International Trade Flows

    Directory of Open Access Journals (Sweden)

    E. Young Song

    2004-12-01

    Full Text Available The purpose of this paper is two-fold. One is to clarify the concept of gravity in international trade flows. The other is to measure the strength of gravity in international trade flows in a way that is consistent with a well-defined concept of gravity. This paper shows that the widely accepted belief that specialization is the source of gravity is not well grounded on theory. We propose to define gravity in international trade as the force that makes the market shares of an exporting country constant in all importing countries, regardless of their sizes. In a stochastic context, we should interpret it as implying that the strength of gravity increases i as the correlation between market shares and market sizes gets weaker and ii as the variance of market shares gets smaller. We estimate an empirical gravity equation thoroughly based on this definition of gravity. We find that a strong degree of gravity exists in most bilateral trade, regardless of income levels of countries, and in trade of most manThe purpose of this paper is two-fold. One is to clarify the concept of gravity in international trade flows. The other is to measure the strength of gravity in international trade flows in a way that is consistent with a well-defined concept of gravity. This paper shows that the widely accepted belief that specialization is the source of gravity is not well grounded on theory. We propose to define gravity in international trade as the force that makes the market shares of an exporting country constant in all importing countries, regardless of their sizes. In a stochastic context, we should interpret it as implying that the strength of gravity increases i as the correlation between market shares and market sizes gets weaker and ii as the variance of market shares gets smaller. We estimate an empirical gravity equation thoroughly based on this definition of gravity. We find that a strong degree of gravity exists in most bilateral trade, regardless of

  8. National and international graduate migration flows.

    Science.gov (United States)

    Mosca, Irene; Wright, Robert E

    2010-01-01

    This article examines the nature of national and international graduate migration flows in the UK. Migration equations are estimated with microdata from a matched dataset of Students and Destinations of Leavers from Higher Education, information collected by the Higher Education Statistical Agency. The probability of migrating is related to a set of observable characteristics using multinomial logit regression. The analysis suggests that migration is a selective process with graduates with certain characteristics having considerably higher probabilities of migrating, both to other regions of the UK and abroad.

  9. CFD investigation of flow through internally riffled boiler tubes

    DEFF Research Database (Denmark)

    Rasmussen, Christian; Houbak, Niels; Sørensen, Jens Nørkær

    1997-01-01

    In this paper we show how to model the swirling flow in an internally riffled boiler tube. The flow field is visualized and the results are compared with measurements.......In this paper we show how to model the swirling flow in an internally riffled boiler tube. The flow field is visualized and the results are compared with measurements....

  10. The Determinants of International News Flow: A Network Analysis.

    Science.gov (United States)

    Kim, Kyungmo; Barnett, George A.

    1996-01-01

    Examines the structure of international news flow and its determinants. Reveals inequality of international news flow between core and periphery, with Western industrialized countries at the center. Finds that the news flow network is structured into eight geographic-linguistic groups. Indicates flow is influenced by a country's economic…

  11. Effect of Hall current and chemical reaction on MHD flow along an exponentially accelerated porous flat plate with internal heat absorption/generation

    International Nuclear Information System (INIS)

    Rath, Pravat Kumar; Dash, G.C.; Patra, Ajit Kumar

    2010-01-01

    Effect of Hall current on the unsteady free convection flow of an electrically conducting incompressible viscous fluid past an exponentially accelerated vertical porous flat plate with internal heat absorption/generation in the presence of foreign gases (such as H 2 , CO 2 , H 2 O, NH 3 ) and chemical reaction has been investigated. An uniform magnetic field transverse to the plate has been applied. The effects of the Hall current m, the hydromagnetic parameter Mt, the chemical reaction parameter K c the Grashof number for heat transfer G r , the Grashof number for mass transfer G c , the Schmidt number S c , the Prandtl number P r and the transpiration parameter α are discussed in detail. (author)

  12. The effect of commercial policy on international migration flows: the case of the United States and Mexico.

    Science.gov (United States)

    Hill, J K; Mendez, J A

    1984-08-01

    "Microeconomic simulations are performed to determine the impact of liberalized commodity trade on Mexican immigrant supply to the United States. The results suggest that a removal of trade barriers will reduce migration flows, but that the reduction will be fairly modest. Specifically, if both countries move from the levels of protection characteristic of the mid-1960s to completely free trade, the ratio of real U.S.-Mexican wages falls by roughly 18 percent. Using an upper bound for the range of empirical estimates of the wage elasticity of immigrant supply, this implies a maximum reduction in migration flows of 35 percent. A unilateral elimination of trade barriers by the United States reduces Mexican immigrant supply by a maximum of 14 percent." excerpt

  13. A Study on Effects of the Transient Compression by Tightly Tied Necktie on Blood Flow in the Internal Jugular Veins Using 2D-PC MRA

    International Nuclear Information System (INIS)

    Kim, Keung Sik; Chung, Tae Sub; Lee, Bum Soo; Park, In Kook; Kim, Hyun Soo; Yoo, Beong Gyu

    2008-01-01

    The 25 healthy male volunteers aged from 20 to 50 years old have been employed in this study. 2D-PC MRA was performed to measure the velocity of the blood flow in the internal carotid artery and internal jugular veins using 3.0T MRI Whole body (signa VH/i GE). ECTRICKS-CEMRA was performed to evaluate the pattern of blood circulation from internal carotid artery to internal jugular vein. Using 2D-PC MRA, the cross-section of the 4th and 5th cervical discs was scanned with 24 cm FOV. Then the speed of blood flow was measured for internal carotid artery and internal jugular vein when the subject wears a necktie tightly and no tie. The average of maximum velocity of internal carotid arteries without a necktie was 72.13 cm/sec in the right side and 74.96 cm/sec in the left side (average 73.54 cm/sec in both sides) while the average of maximum velocity of internal jugular veins without a necktie was -34.45 cm/sec in the right side and -24.99 cm/sec in the left side (-29.72 cm/sec in both sides). However, when wearing a necktie tightly, the average of maximum velocity of internal carotid arteries was 61.35 cm/sec in the right side and 65.19 cm/sec in the left side (average 63.27 cm/sec in both sides) while the average of maximum velocity of internal jugular veins was -22.14 cm/sec in the right side and -17.93 cm/sec in the left side (-20.03 cm/sec in both sides). With the necktie tightly knotted, the average blood flow speed of both internal carotid arteries slightly decreased to 86% (63.27/73.54 cm/sec) compared to no tie case in which both internal jugularveins significantly went down to 67% (-20.03/-29.72 cm/sec). Thus it is suggested that wearing a necktie affects the circulation of internal jugular veins (33% decrease in blood flow speed) more significantly than that of internal carotid artery (14% decrease in blood flow speed). Without a necktie, ECTRICKS-CEMRA showed natural blood circulation patterns of internal carotid arteries and internal jugular veins without

  14. The effect of channel flow pattern on internal properties distribution of a proton exchange membrane fuel cell for cathode starvation conditions

    International Nuclear Information System (INIS)

    Ko, Dong Soo; Kang, Young Min; Yang, Jang Sik; Jeong, Ji Hwan; Choi, Gyung Min; Kim, Duck Jool

    2010-01-01

    The effect of channel flow pattern on the internal properties distribution of a proton exchange membrane fuel cell (PEMFC) for cathode starvation conditions in a unit cell was investigated through numerical studies and experiments. The polarization curves of a lab-scale mixed serpentine PEMFC were measured with increasing current loads for different cell temperatures (40, 50, and 60 .deg. C) at a relative humidity of 100%. To study the local temperature on the membrane, the water content in the MEA, and the gas velocity in terms of the channel type of the PEMFC with operating characteristics, numerical studies using the es-pemfc module of STAR-CD, which have been matched to the experimental data, were conducted in detail. The water content and velocity at the cathode channel bend of the mixed serpentine channel were relatively higher than those at the single and double channels. Conversely, the local temperature and mean temperature on the membrane of a single serpentine channel were the highest among all channels. These results can be used to design the PEMFC system, the channel flow field, and the cooling device

  15. Sound attenuation of a finite length dissipative flow duct silencer with internal mean flow in the absorbent

    Science.gov (United States)

    Cummings, A.; Chang, I.-J.

    1988-11-01

    Internal mean flow within the pores of a bulk-reacting porous acoustic absorbent, driven by mean static pressure gradients, is shown here to be an important feature of the acoustics of dissipative silencers in flow ducts, particularly in the case of internal combustion engine exhaust silencers. Theoretical treatments are presented here, both to describe the effect of internal flow on the bulk acoustic perties of the porous medium and to find the effect of the absorbent in situ, in the form of the sound transmission loss of the silencer. The measured transmission loss of an experimental silencer is compared to predicted data and good agreement between the two is obtained. The effects of mean fluid flow in the central passage and internal flow in the absorbent are separately demonstrated.

  16. FOREWORD: International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

    Science.gov (United States)

    Wu, Yulin

    2015-01-01

    multiphase flow detection Fluid-structure interaction induced by cavitation and multiphase flow Multi-scale modelling of cavitating flows and Multiphase Flow Cavitation nuclei: theory and experiments Supercavitation and its applications Synergetic effects of cavitation and silt-laden erosion Shock waves and microjets generated by cavitation Nonlinear oscillations of gas and vapour bubbles Fundamentals of physics of acoustic cavitation Sonochemistry and sonoluminescence Biomedical applications of cavitation effects Ultrasonic cavitation for molten metal treatment Cavitation for enhanced heat transfer The ISCM 2014 brought together 95 scientists, researchers and graduate students from 11 countries, affiliated with universities, technology centers and industrial firms to debate topics related to advanced technologies for cavitation and Multiphase Flow, which would enhance the sustainable development of cavitation and Multiphase Flow in interdisciplinary sciences and technology. The technical committee selected 54 technical papers on the following topics: (i) Hydrodynamic Cavitation, (ii) Super Cavitation, (iii) Pump Cavitation, (iv) Acoustic Cavitation, (v) Interdisciplinary Research of Cavitation and Multi-Phase Flows, and 13 invited plenary and invited forum lectures, which were presented at the symposium, to be included in the proceedings. All the papers of ISCM 2014, which are published in this Volume of IOP Conference Series: Materials Science and Engineering, had been peer reviewed through processes administered by the editors of the ISCM 2014, those are Yulin WU, Shouqi YUAN, Zhengwei WANG, Shuhong LIU, Xingqi LUO, Fujun WANG and Guoyu WANG. The papers published in this Volume include 54 technical papers and 3 full length texts of the invited lectures. We sincerely hope that the International Symposium on Cavitation and Multiphase Flow is a significant step forward in the world wide efforts to address the present challenges in the modern science and technology. Professor

  17. International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

    International Nuclear Information System (INIS)

    Wu, Yulin

    2015-01-01

    multiphase flow detection Fluid-structure interaction induced by cavitation and multiphase flow Multi-scale modelling of cavitating flows and Multiphase Flow Cavitation nuclei: theory and experiments Supercavitation and its applications Synergetic effects of cavitation and silt-laden erosion Shock waves and microjets generated by cavitation Nonlinear oscillations of gas and vapour bubbles Fundamentals of physics of acoustic cavitation Sonochemistry and sonoluminescence Biomedical applications of cavitation effects Ultrasonic cavitation for molten metal treatment Cavitation for enhanced heat transfer The ISCM 2014 brought together 95 scientists, researchers and graduate students from 11 countries, affiliated with universities, technology centers and industrial firms to debate topics related to advanced technologies for cavitation and Multiphase Flow, which would enhance the sustainable development of cavitation and Multiphase Flow in interdisciplinary sciences and technology. The technical committee selected 54 technical papers on the following topics: (i) Hydrodynamic Cavitation, (ii) Super Cavitation, (iii) Pump Cavitation, (iv) Acoustic Cavitation, (v) Interdisciplinary Research of Cavitation and Multi-Phase Flows, and 13 invited plenary and invited forum lectures, which were presented at the symposium, to be included in the proceedings. All the papers of ISCM 2014, which are published in this Volume of IOP Conference Series: Materials Science and Engineering, had been peer reviewed through processes administered by the editors of the ISCM 2014, those are Yulin WU, Shouqi YUAN, Zhengwei WANG, Shuhong LIU, Xingqi LUO, Fujun WANG and Guoyu WANG. The papers published in this Volume include 54 technical papers and 3 full length texts of the invited lectures. We sincerely hope that the International Symposium on Cavitation and Multiphase Flow is a significant step forward in the world wide efforts to address the present challenges in the modern science and technology. Professor

  18. Effects of aeration and internal recycle flow on nitrous oxide emissions from a modified Ludzak-Ettinger process fed with glycerol.

    Science.gov (United States)

    Song, Kang; Suenaga, Toshikazu; Harper, Willie F; Hori, Tomoyuki; Riya, Shohei; Hosomi, Masaaki; Terada, Akihiko

    2015-12-01

    Nitrous oxide (N2O) is emitted from a modified Ludzak-Ettinger (MLE) process, as a primary activated sludge system, which requires mitigation. The effects of aeration rates and internal recycle flow (IRF) ratios on N2O emission were investigated in an MLE process fed with glycerol. Reducing the aeration rate from 1.5 to 0.5 L/min increased gaseous the N2O concentration from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 54.4 and 53.4 %, respectively. During the period of higher aeration, the N2O-N conversion ratio was 0.9 % and the potential N2O reducers were predominantly Rhodobacter, which accounted for 21.8 % of the total population. Increasing the IRF ratio from 3.6 to 7.2 decreased the N2O emission rate from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 56 and 48 %, respectively. This study suggests effective N2O mitigation strategies for MLE systems.

  19. Are international fund flows pro- or counter-cyclical?

    NARCIS (Netherlands)

    Li, Suxiao; de Haan, Jakob; Scholtens, Bert; Yang, Haizhen

    2015-01-01

    We investigate whether international fund flows are pro-or counter-cyclical by employing a concordance index. International fund flows are investments in bond and equity markets by institutional investors, such as mutual funds, exchange traded funds, closed-end funds and hedge funds. We find that

  20. Internal flow measurement in transonic compressor by PIV technique

    Science.gov (United States)

    Wang, Tongqing; Wu, Huaiyu; Liu, Yin

    2001-11-01

    The paper presents some research works conducted in National Key Laboratory of Aircraft Engine of China on the shock containing supersonic flow measurement as well as the internal flow measurement of transoijc compressor by PIC technique. A kind of oil particles in diameter about 0.3 micrometers containing in the flow was discovered to be a very good seed for the PIV measurement of supersonic jet flow. The PIV measurement in over-expanded supersonic free jet and in the flow over wages show a very clear shock wave structure. In the PIV internal flow measurement of transonic compressor a kind of liquid particle of glycol was successful to be used as the seed. An illumination periscope with sheet forming optics was designed and manufactured, it leaded the laser shot generated from an integrate dual- cavity Nd:YAG laser of TSI PIV results of internal flow of an advanced low aspect ratio transonic compressor were shown and discussed briefly.

  1. 6th International Workshop on Model Reduction in Reactive Flow

    Science.gov (United States)

    2018-01-01

    reduction in reacting flow . Registration DateRegistration TypeFirst Name Middle NameLast Name Affiliation US State /Canadian ProvinceState/Province/R gion...Report: 6th International Workshop on Model Reduction in Reactive Flow The views, opinions and/or findings contained in this report are those of the...Agreement Number: W911NF-17-1-0121 Organization: Princeton University Title: 6th International Workshop on Model Reduction in Reactive Flow Report Term

  2. Numerical investigation on the effect of injection pressure on the internal flow characteristics for diethyl ether, dimethyl ether and diesel fuel injectors using CFD

    Directory of Open Access Journals (Sweden)

    Vijayakumar Thulasi

    2011-01-01

    Full Text Available The spray characteristics of the diesel fuel are greatly affected by the cavitation formed inside the injector due to the high pressure differential across the nozzle. Many researchers across the globe are exploring the potential of using diethyl ether and dimethyl ether as an alternate for diesel fuel to meet the strict emission norms. Due to the variation in the fuel properties the internal flow characteristics in injectors for ether fuels are expected to be different from that of the diesel fuel. In this paper computational technique is used to study and compare the internal flow characteristics of diethyl ether, dimethyl ether and diesel fuel. The two phase flow model considering the fuel as a mixture of liquid and vapor is adopted for the simulation study. The injection pressure is varied from 100 to 400 bar and the flow characteristics of all three fuels are simulated and compared. Results indicate that all three fuels have distinct cavitating patterns owing to different property values. The dimethyl ether is found to be more cavitating than diesel and diethyl ether fuels as expected. The mass of fuel injected are found to be decreasing for the ether fuels when compared with diesel fuel at all injection pressures.

  3. 5th International Conference on Jets, Wakes and Separated Flows

    CERN Document Server

    2016-01-01

    This volume collects various contributions from the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015) that took place in Stockholm during June 2015. Researchers from all around the world presented their latest results concerning fundamental and applied aspects of fluid dynamics. With its general character, the conference embraced many aspects of fluid dynamics, such as shear flows, multiphase flows and vortex flows, for instance. The structure of the present book reflects the variety of topics treated within the conference i.e. Jets, Wakes, Separated flows, Vehicle aerodynamics, Wall-bounded and confined flows, Noise, Turbomachinery flows, Multiphase and reacting flows, Vortex dynamics, Energy-related flows and a section dedicated to Numerical analyses.

  4. Pulsatile pipe flow transition: Flow waveform effects

    Science.gov (United States)

    Brindise, Melissa C.; Vlachos, Pavlos P.

    2018-01-01

    Although transition is known to exist in various hemodynamic environments, the mechanisms that govern this flow regime and their subsequent effects on biological parameters are not well understood. Previous studies have investigated transition in pulsatile pipe flow using non-physiological sinusoidal waveforms at various Womersley numbers but have produced conflicting results, and multiple input waveform shapes have yet to be explored. In this work, we investigate the effect of the input pulsatile waveform shape on the mechanisms that drive the onset and development of transition using particle image velocimetry, three pulsatile waveforms, and six mean Reynolds numbers. The turbulent kinetic energy budget including dissipation rate, production, and pressure diffusion was computed. The results show that the waveform with a longer deceleration phase duration induced the earliest onset of transition, while the waveform with a longer acceleration period delayed the onset of transition. In accord with the findings of prior studies, for all test cases, turbulence was observed to be produced at the wall and either dissipated or redistributed into the core flow by pressure waves, depending on the mean Reynolds number. Turbulent production increased with increasing temporal velocity gradients until an asymptotic limit was reached. The turbulence dissipation rate was shown to be independent of mean Reynolds number, but a relationship between the temporal gradients of the input velocity waveform and the rate of turbulence dissipation was found. In general, these results demonstrated that the shape of the input pulsatile waveform directly affected the onset and development of transition.

  5. Fuel cell with internal flow control

    Science.gov (United States)

    Haltiner, Jr., Karl J.; Venkiteswaran, Arun [Karnataka, IN

    2012-06-12

    A fuel cell stack is provided with a plurality of fuel cell cassettes where each fuel cell cassette has a fuel cell with an anode and cathode. The fuel cell stack includes an anode supply chimney for supplying fuel to the anode of each fuel cell cassette, an anode return chimney for removing anode exhaust from the anode of each fuel cell cassette, a cathode supply chimney for supplying oxidant to the cathode of each fuel cell cassette, and a cathode return chimney for removing cathode exhaust from the cathode of each fuel cell cassette. A first fuel cell cassette includes a flow control member disposed between the anode supply chimney and the anode return chimney or between the cathode supply chimney and the cathode return chimney such that the flow control member provides a flow restriction different from at least one other fuel cell cassettes.

  6. The gravity model specification for modeling international trade flows and free trade agreement effects: a 10-year review of empirical studies

    OpenAIRE

    Kepaptsoglou, Konstantinos; Karlaftis, Matthew G.; Tsamboulas, Dimitrios

    2010-01-01

    The gravity model has been extensively used in international trade research for the last 40 years because of its considerable empirical robustness and explanatory power. Since their introduction in the 1960's, gravity models have been used for assessing trade policy implications and, particularly recently, for analyzing the effects of Free Trade Agreements on international trade. The objective of this paper is to review the recent empirical literature on gravity models, highlight best practic...

  7. Investigating the effect of crevice flow on internal combustion engines using a new simple crevice model implemented in a CFD code

    International Nuclear Information System (INIS)

    Rakopoulos, C.D.; Kosmadakis, G.M.; Dimaratos, A.M.; Pariotis, E.G.

    2011-01-01

    A theoretical investigation is conducted to examine the way the crevice regions affect the mean cylinder pressure, the in-cylinder temperature, and the velocity field of internal combustion engines running at motoring conditions. For the calculation of the wall heat flux, a wall heat transfer formulation developed by the authors is used, while for the simulation of the crevices and the blow-by a newly developed simplified simulation model is presented herein. These sub-models are incorporated into an in-house Computational Fluid Dynamics (CFD) code. The main advantage of the new crevice model is that it can be applied in cases where no detailed information of the ring-pack configuration is available, which is important as this information is rarely known or may have been altered during the engine's life. Thus, an adequate estimation of the blow-by effect on the cylinder pressure can be drawn. To validate the new model, the measured in-cylinder pressure traces of a diesel engine, located at the authors' laboratory, running under motoring conditions at four engine speeds were used as reference, together with measured velocity profiles and turbulence data of a motored spark-ignition engine. Comparing the predicted and measured cylinder pressure traces of the diesel engine for all cases examined, it is observed that by incorporating the new crevice sub-model into the in-house CFD code, significant improvements on the predictive accuracy of the model is obtained. The calculated cylinder pressure traces almost coincide with the measured ones, thus avoiding the use of any calibration constants as would have been the case with the crevice effect omitted. Concerning the radial and swirl velocity profiles and the turbulent kinetic energy measured in the spark-ignition engine, the validation process revealed that the developed crevice model has a minor influence on the aforementioned parameters. The theoretical study has been extended by investigating in the same spark

  8. Globalisation of water resources: International virtual water flows in relation to international crop trade

    NARCIS (Netherlands)

    Hoekstra, Arjen Ysbert; Hung, P.Q.

    2005-01-01

    The water that is used in the production process of a commodity is called the ‘virtual water’ contained in the commodity. International trade of commodities brings along international flows of virtual water. The objective of this paper is to quantify the volumes of virtual water flows between

  9. Are international fund flows related to exchange rate dynamics?

    NARCIS (Netherlands)

    Li, Suxiao; de Haan, Jakob; Scholtens, Bert

    2018-01-01

    Employing monthly data for 53 countries between 1996 and 2015, we investigate the relationship between international fund flows and exchange rate dynamics. We find strong co-movement between funds flows (as measured with the EPFR Global data base) and bilateral real exchange rates vis-à-vis the USD.

  10. Formation and distribution of international tourism flows in geographical space

    Directory of Open Access Journals (Sweden)

    Oleksandr Korol

    2017-10-01

    Full Text Available Properties of geographical space that are of key importance for international tourism, as length and discreteness, are analyzed in the article. Length makes tourists cover distances, whereas discreteness manifests itself in spatial heterogeneity. Tourism in conditions of homogeneous space is vain. That is, heterogeneity brings sense to travels as well as determines their direction. So, the effect of geographical space’s length and spatial heterogeneity on formation and distribution of tourism flows is assessed, international tourism’s geographical essence is disclosed also. Apperception of geographical space in usual environment and its effect on tourist’s original motives are described. Following the bases of behaviorism, the tourism original motives, in particular those for migration, comfort, contrast and aesthetics are substantiated. The motive for migration is a kind of “pushing” tourists outside their usual environment. To stop all fears that may cause anxiety in destination, the latter should guarantee satisfaction of those human needs which A. Maslow refers to as basic needs. The necessity to satisfy these needs forms in tourists the motive for comfort. Closely located destinations in neighboring countries can be of little difference form usual environment. Driven by the motive for contrast, tourists aspire to visit places that totally differ from their usual environment, and contrast (are exotic to it. Thus, the motive for contrast seemingly “pulls” the tourists up to certain (exotic destinations. Finally, following the considered spatial specificities of land surface and tourist-driving original motives, a conceptual model of formation and distribution of international tourism flows in geographical space is developed.

  11. South Korea's Experience with International Capital Flows

    OpenAIRE

    Marcus Noland

    2005-01-01

    South Korea%u2019s experience is unparalleled in its combination of sustained prosperity, capital controls, and financial crisis. Over several decades, South Korea experienced rapid sustained growth in the presence of capital controls. These controls and the de-linking of domestic and international financial markets were an essential component of the country's state-led development strategy. As the country developed, opportunities for easy technological catch-up eroded, requiring more sophist...

  12. Nutrient flows in international trade: Ecology and policy issues

    International Nuclear Information System (INIS)

    Grote, Ulrike; Craswell, Eric; Vlek, Paul

    2005-01-01

    Impacts of increasing population pressure on food demand and land resources has sparked interest in nutrient balances and flows at a range of scales. West Asia/North Africa, China, and sub-Saharan Africa are net importers of NPK in agricultural commodities. These imported nutrients do not, however, redress the widely recognized declines in fertility in sub-Saharan African soils, because the nutrients imported are commonly concentrated in the cities, creating waste disposal problems rather than alleviating deficiencies in rural soils. Countries with a net loss of NPK in agricultural commodities are the major food exporting countries-the United States, Australia, and some Latin American countries. In the case of the United States, exports of NPK will increase from 3.1 Tg in 1997 to 4.8 Tg in 2020. The results suggest that between 1997 and 2020, total international net flows of NPK in traded agricultural commodities will double to 8.8 million tonnes. Against this background, the paper analyses the impact of different policy measures on nutrient flows and balances. This includes not only the effects of agricultural trade liberalization and the reduction of subsidies, but also the more direct environmental policies like nutrient accounting schemes, eco-labeling, and nutrient trading. It finally stresses the need for environmental costs to be factored into the debate on nutrient management and advocates more inter-disciplinary research on these important problems

  13. Computation of high Reynolds number internal/external flows

    Science.gov (United States)

    Cline, M. C.; Wilmoth, R. G.

    1981-01-01

    A general, user oriented computer program, called VNAP2, was developed to calculate high Reynolds number, internal/ external flows. The VNAP2 program solves the two dimensional, time dependent Navier-Stokes equations. The turbulence is modeled with either a mixing-length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack Scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented.

  14. Computation of high Reynolds number internal/external flows

    International Nuclear Information System (INIS)

    Cline, M.C.; Wilmoth, R.G.

    1981-01-01

    A general, user oriented computer program, called VNAP2, has been developed to calculate high Reynolds number, internal/external flows. VNAP2 solves the two-dimensional, time-dependent Navier-Stokes equations. The turbulence is modeled with either a mixing-length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented

  15. Internal flow of acoustically levitated drops undergoing sectorial oscillations

    International Nuclear Information System (INIS)

    Shen, C.L.; Xie, W.J.; Yan, Z.L.; Wei, B.

    2010-01-01

    We present the experimental observation and theoretical analysis of fluid flow in acoustically levitated water drop undergoing sectorial oscillations. The fluid always flows between the extended sections and the compressed sections. The magnitude of fluid velocity decreases from the equatorial fringe to the centre of levitated drop. The maximum fluid velocity is 60-160 mm/s and the Reynolds number of the oscillations is estimated to be 137-367. The internal flow of the drop is analyzed as potential flow, and the fluid velocity is found to be horizontal. In the equatorial plane, the calculated stream lines and velocity profiles agree well with the experimental observations.

  16. Numerical simulation of internal flow in mixed-flow waterjet propulsion

    International Nuclear Information System (INIS)

    Wu, T T; Pan, Z Y; Zhang, D Q; Jia, Y Y

    2012-01-01

    In order to reveal the internal flow characteristic of a mixed-flow waterjet propulsion, a mixed-flow waterjet propulsion under different conditions was simulated based on multi-reference frame(MRF), the standard k − ε turbulent model and SIMPLEC algorithm. The relationship between pump performance instability and internal flow was obtained. The numerical results showed that characteristic instability occurred at 0.65-0.67Q BEP , the reason is that the backflow on the vaned diffuser hub-side blocks the downstream flow from the impeller. Therefore, the flow separates on the pressure surface of the impeller outlet and a strong vortex is generated, then the characteristic instability appeared due to the instability of internal flow. Backflow was found in diffuser passage at 0.65 Q BEP and 0.85 Q BEP , as flow rate decreases, the backflow region and velocity increases. Pressure fluctuation at diffuser inlet and diffuser passages was severe at at 0.65 Q BEP . According to the numerical simulation, the mixed-flow waterjet propulsion has characteristic instability at partial flow rate condition.

  17. Internal and vorticity waves in decaying stratified flows

    Science.gov (United States)

    Matulka, A.; Cano, D.

    2009-04-01

    Most predictive models fail when forcing at the Rossby deformation Radius is important and a large range of scales have to be taken into account. When mixing of reactants or pollutants has to be accounted, the range of scales spans from hundreds of Kilometers to the Bachelor or Kolmogorov sub milimiter scales. We present some theoretical arguments to describe the flow in terms of the three dimensional vorticity equations, using a lengthscale related to the vorticity (or enstrophy ) transport. Effect of intermittent eddies and non-homogeneity of diffusion are also key issues in the environment because both stratification and rotation body forces are important and cause anisotropy/non-homogeneity. These problems need further theoretical, numerical and observational work and one approach is to try to maximize the relevant geometrical information in order to understand and therefore predict these complex environmental dispersive flows. The importance of the study of turbulence structure and its relevance in diffusion of contaminants in environmental flows is clear when we see the effect of environmental disasters such as the Prestige oil spill or the Chernobil radioactive cloud spread in the atmosphere. A series of Experiments have been performed on a strongly stratified two layer fluid consisting of Brine in the bottom and freshwater above in a 1 square meter tank. The evolution of the vortices after the passage of a grid is video recorded and Particle tracking is applied on small pliolite particles floating at the interface. The combination of internal waves and vertical vorticity produces two separate time scales that may produce resonances. The vorticity is seen to oscilate in a complex way, where the frecuency decreases with time.

  18. Flow Physics and Control for Internal and External Aerodynamics

    Science.gov (United States)

    Wygnanski, I.

    2010-01-01

    Exploiting instabilities rather than forcing the flow is advantageous. Simple 2D concepts may not always work. Nonlinear effects may result in first order effect. Interaction between spanwise and streamwise vortices may have a paramount effect on the mean flow, but this interaction may not always be beneficial.

  19. Internal Flow of Contra-Rotating Small Hydroturbine at Off- Design Flow Rates

    Science.gov (United States)

    SHIGEMITSU, Toru; TAKESHIMA, Yasutoshi; OGAWA, Yuya; FUKUTOMI, Junichiro

    2016-11-01

    Small hydropower generation is one of important alternative energy, and enormous potential lie in the small hydropower. However, efficiency of small hydroturbines is lower than that of large one. Then, there are demands for small hydroturbines to keep high performance in wide flow rate range. Therefore, we adopted contra-rotating rotors, which can be expected to achieve high performance. In this research, performance of the contra-rotating small hydroturbine with 60mm casing diameter was investigated by an experiment and numerical analysis. Efficiency of the contra-rotating small hydroturbine was high in pico-hydroturbine and high efficiency could be kept in wide flow rate range, however the performance of a rear rotor decreased significantly in partial flow rates. Then, internal flow condition, which was difficult to measure experimentally, was investigated by the numerical flow analysis. Then, a relation between the performance and internal flow condition was considered by the numerical analysis result.

  20. Analysis of diabatic flow modification in the internal boundary layer

    DEFF Research Database (Denmark)

    Floors, Rogier; Gryning, Sven-Erik; Pena Diaz, Alfredo

    2011-01-01

    Measurements at two meteorological masts in Denmark, Horns Rev in the sea and Høvsøre near the coastline on land, are used to analyze the behaviour of the flow after a smooth-to-rough change in surface conditions. The study shows that the wind profile within the internal boundary layer is control......Measurements at two meteorological masts in Denmark, Horns Rev in the sea and Høvsøre near the coastline on land, are used to analyze the behaviour of the flow after a smooth-to-rough change in surface conditions. The study shows that the wind profile within the internal boundary layer...

  1. 2nd International Conference on Multiphase Flow - ICMF '95

    CERN Document Server

    Fukano, T; Bataille, Jean

    1995-01-01

    There is increasing world-wide interest in obtaining an understanding of various multiphase flow phenomena and problems in terms of a common language of multiphase flow. This volume contains state-of-the-art papers which have been contributed from all over the world by experts working on all aspects of multiphase flows. The volume also highlights international technology-sharing in the fields of energy, environment and public health, in order to create a brighter and sustainable future for man and for all life in the next century. It is intended that this volume will serve as a major source of

  2. International Conference on Instability and Control of Massively Separated Flows

    CERN Document Server

    Soria, Julio

    2015-01-01

    This book contains the outcome of the international meeting on instability, control and noise generated by massive flow separation that was organized at the Monash Center, in Prato, Italy, September 4-6, 2013. The meeting served as the final review of the EU-FP7 Instability and Control of Massively Separated Flows Marie Curie travel grant and was supported by the European Office of Aerospace Research and Development. Fifty leading specialists from twelve countries reviewed the progress made since the 50s of the last century and discussed modern analysis techniques, advanced experimental flow diagnostics, and recent developments in active flow control techniques from the incompressible to the hypersonic regime. Applications involving massive flow separation and associated instability and noise generation mechanisms of interest to the aeronautical, naval and automotive industries have been addressed from a theoretical, numerical or experimental point of view, making this book a unique source containing the stat...

  3. Numerical Investigation of the Internal Flow in a Banki Turbine

    Directory of Open Access Journals (Sweden)

    Jesús De Andrade

    2011-01-01

    Full Text Available The paper refers to the numerical analysis of the internal flow in a hydraulic cross-flow turbine type Banki. A 3D-CFD steady state flow simulation has been performed using ANSYS CFX codes. The simulation includes nozzle, runner, shaft, and casing. The turbine has a specific speed of 63 (metric units, an outside runner diameter of 294 mm. Simulations were carried out using a water-air free surface model and k-ε turbulence model. The objectives of this study were to analyze the velocity and pressure fields of the cross-flow within the runner and to characterize its performance for different runner speeds. Absolute flow velocity angles are obtained at runner entrance for simulations with and without the runner. Flow recirculation in the runner interblade passages and shocks of the internal cross-flow cause considerable hydraulic losses by which the efficiency of the turbine decreases significantly. The CFD simulations results were compared with experimental data and were consistent with global performance parameters.

  4. Hybrid continuum–molecular modelling of multiscale internal gas flows

    International Nuclear Information System (INIS)

    Patronis, Alexander; Lockerby, Duncan A.; Borg, Matthew K.; Reese, Jason M.

    2013-01-01

    We develop and apply an efficient multiscale method for simulating a large class of low-speed internal rarefied gas flows. The method is an extension of the hybrid atomistic–continuum approach proposed by Borg et al. (2013) [28] for the simulation of micro/nano flows of high-aspect ratio. The major new extensions are: (1) incorporation of fluid compressibility; (2) implementation using the direct simulation Monte Carlo (DSMC) method for dilute rarefied gas flows, and (3) application to a broader range of geometries, including periodic, non-periodic, pressure-driven, gravity-driven and shear-driven internal flows. The multiscale method is applied to micro-scale gas flows through a periodic converging–diverging channel (driven by an external acceleration) and a non-periodic channel with a bend (driven by a pressure difference), as well as the flow between two eccentric cylinders (with the inner rotating relative to the outer). In all these cases there exists a wide variation of Knudsen number within the geometries, as well as substantial compressibility despite the Mach number being very low. For validation purposes, our multiscale simulation results are compared to those obtained from full-scale DSMC simulations: very close agreement is obtained in all cases for all flow variables considered. Our multiscale simulation is an order of magnitude more computationally efficient than the full-scale DSMC for the first and second test cases, and two orders of magnitude more efficient for the third case

  5. Performance and internal flow condition of mini centrifugal pump with splitter blades

    International Nuclear Information System (INIS)

    Shigemitsu, T; Fukutomi, J; Kaji, K; Wada, T

    2012-01-01

    Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. The blade-to-blade low velocity regions are suppressed in the case with the splitter blades and the total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

  6. Effective planning for internal audit

    OpenAIRE

    Cirtautas, Marius

    2016-01-01

    The purpose of this thesis is to find a way to effectively plan for internal audit. Conditions necessary for effective planning are formulated by using analysis of scientific literature. In second part author suggests a model for effective internal audit planning. In third part model is applied and analyzed using a case study.

  7. Flow Control Device Evaluation for an Internal Flow with an Adverse Pressure Gradient

    Science.gov (United States)

    Jenkins, Luther N.; Gorton, Susan Althoff; Anders, Scott G.

    2002-01-01

    The effectiveness of several active and passive devices to control flow in an adverse pressure gradient with secondary flows present was evaluated in the 15 Inch Low Speed Tunnel at NASA Langley Research Center. In this study, passive micro vortex generators, micro bumps, and piezoelectric synthetic jets were evaluated for their flow control characteristics using surface static pressures, flow visualization, and 3D Stereo Digital Particle Image Velocimetry. Data also were acquired for synthetic jet actuators in a zero flow environment. It was found that the micro vortex generator is very effective in controlling the flow environment for an adverse pressure gradient, even in the presence of secondary vortical flow. The mechanism by which the control is effected is a re-energization of the boundary layer through flow mixing. The piezoelectric synthetic jet actuators must have sufficient velocity output to produce strong longitudinal vortices if they are to be effective for flow control. The output of these devices in a laboratory or zero flow environment will be different than the output in a flow environment. In this investigation, the output was higher in the flow environment, but the stroke cycle in the flow did not indicate a positive inflow into the synthetic jet.

  8. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in

  9. Particle flow calorimetry at the international linear collider

    Indian Academy of Sciences (India)

    Particle flow calorimetry at the international linear ... It is widely believed that the most promising strategy for achieving a jet ... this level of performance for two main reasons. Firstly ... (i) Tracking: For the studies presented in this paper, the track pattern ... that particles propagating outward from the interaction region will cross ...

  10. Beam Flutter and Energy Harvesting in Internal Flow

    Science.gov (United States)

    Tosi, Luis Phillipe; Colonius, Tim; Sherrit, Stewart; Lee, Hyeong Jae

    2017-11-01

    Aeroelastic flutter, largely studied for causing engineering failures, has more recently been used as a means of extracting energy from the flow. Particularly, flutter of a cantilever or an elastically mounted plate in a converging-diverging flow passage has shown promise as an energy harvesting concept for internal flow applications. The instability onset is observed as a function of throat velocity, internal wall geometry, fluid and structure material properties. To enable these devices, our work explores features of the fluid-structure coupled dynamics as a function of relevant nondimensional parameters. The flutter boundary is examined through stability analysis of a reduced order model, and corroborated with numerical simulations at low Reynolds number. Experiments for an energy harvester design are qualitatively compared to results from analytical and numerical work, suggesting a robust limit cycle ensues due to a subcritical Hopf bifurcation. Bosch Corporation.

  11. Factors Affecting the Internal Audit Effectiveness

    OpenAIRE

    Mustika, Adhista Cahya

    2015-01-01

    This study tests the factors that influence the internal audit effectiveness, including internal auditor competencies, internal auditor independence, auditee support to internal audit activity, and the internal and external auditor relationship. Using the internal auditor inspectorate in Java Province, Indonesia, we found that the internal audit effectiveness can be attained through increase internal audit competence, independence and strong relationship between internal and external auditor....

  12. International migration flows. Framework for understanding and current features.

    Directory of Open Access Journals (Sweden)

    Colectivo IOÉ

    2016-10-01

    Full Text Available The present article aims to outline a framework for the understanding of the present international migratory flows as well as to outline their main traits. In order to do this, we first group together the different migratory flows produced since the sixteenth century up to the mid seventies in the twentieth  century, stopping then for a closer look at the present situation which register the impact of economic globalization, translating it into an increase of said flows and, above all, to their enormous diversification. To end, we make a brief balance of the present period and a critical evaluation on the meaning of one of the flows which attracts most attention, economic migrations south-north, because these are the ones which have the most impact on developed countries.

  13. Thermoinduced plastic flow and shape memory effects

    Directory of Open Access Journals (Sweden)

    Xiao Heng

    2011-01-01

    Full Text Available We propose an enhanced form of thermocoupled J2-flow models of finite deformation elastoplasticity with temperature-dependent yielding and hardening behaviour. The thermomechanical constitutive structure of these models is rendered free and explicit in the rigorous sense of thermodynamic consistency. Namely, with a free energy function explicitly introduced in terms of almost any given form of the thermomechanical constitutive functions, the requirements from the second law are identically fulfilled with positive internal dissipation. We study the case when a dependence of yielding and hardening on temperature is given and demonstrate that thermosensitive yielding with anisotropic hardening may give rise to appreciable plastic flow either in a process of heating or in a cyclic process of heating/cooling, thus leading to the findings of one- and two-way thermoinduced plastic flow. We then show that such theoretical findings turn out to be the effects found in shape memory materials, such as one- and two-way memory effects. Thus, shape memory effects may be explained to be thermoinduced plastic flow resulting from thermosensitive yielding and hardening behaviour. These and other relevant facts may suggest that, from a phenomenological standpoint, thermocoupled elastoplastic J2-flow models with thermosensitive yielding and hardening may furnish natural, straightforward descriptions of thermomechanical behaviour of shape memory materials.

  14. Prediction of strongly-heated internal gas flows

    International Nuclear Information System (INIS)

    McEligot, D.M.; Shehata, A.M.; Kunugi, Tomoaki

    1997-01-01

    The purposes of the present article are to remind practitioners why the usual textbook approaches may not be appropriate for treating gas flows heated from the surface with large heat fluxes and to review the successes of some recent applications of turbulence models to this case. Simulations from various turbulence models have been assessed by comparison to the measurements of internal mean velocity and temperature distributions by Shehata for turbulent, laminarizing and intermediate flows with significant gas property variation. Of about fifteen models considered, five were judged to provide adequate predictions

  15. Virtual Seafloor Reduces Internal Wave Generation by Tidal Flow

    Science.gov (United States)

    Zhang, Likun; Swinney, Harry L.

    2014-03-01

    Our numerical simulations of tidal flow of a stratified fluid over periodic knife-edge ridges and random topography reveal that the time-averaged tidal energy converted into internal gravity wave radiation arises only from the section of a ridge above a virtual seafloor. The average radiated power is approximated by the power predicted by linear theory if the height of the ridge is measured relative to the virtual floor. The concept of a virtual floor can extend the applicability of linear theory to global predictions of the conversion of tidal energy into internal wave energy in the oceans.

  16. Effects of Pulsating Flow on Mass Flow Balance and Surge Margin in Parallel Turbocharged Engines

    OpenAIRE

    Thomasson, Andreas; Eriksson, Lars

    2015-01-01

    The paper extends a mean value model of a parallel turbocharged internal combustion engine with a crank angle resolved cylinder model. The result is a 0D engine model that includes the pulsating flow from the intake and exhaust valves. The model captures variations in turbo speed and pressure, and therefore variations in the compressor operating point, during an engine cycle. The model is used to study the effect of the pulsating flow on mass flow balance and surge margin in parallel turbocha...

  17. Holographic aids for internal combustion engine flow studies

    Science.gov (United States)

    Regan, C.

    1984-01-01

    Worldwide interest in improving the fuel efficiency of internal combustion (I.C.) engines has sparked research efforts designed to learn more about the flow processes of these engines. The flow fields must be understood prior to fuel injection in order to design efficient valves, piston geometries, and fuel injectors. Knowledge of the flow field is also necessary to determine the heat transfer to combustion chamber surfaces. Computational codes can predict velocity and turbulence patterns, but experimental verification is mandatory to justify their basic assumptions. Due to their nonintrusive nature, optical methods are ideally suited to provide the necessary velocity verification data. Optical sytems such as Schlieren photography, laser velocimetry, and illuminated particle visualization are used in I.C. engines, and now their versatility is improved by employing holography. These holographically enhanced optical techniques are described with emphasis on their applications in I.C. engines.

  18. Study of the Internal Flow and Evaporation Characteristic Inside a Water Droplet on a Vertical Vibrating Hydrophobic Surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang-Seok; Lim, Hee-Chang [Pusan Nat’l Univ., Busan (Korea, Republic of)

    2017-01-15

    Thermal Marangoni flow has been observed inside droplets on heated surfaces, finally resulting in a coffee stain effect. This study aims to visualize and control the thermal Marangoni flow by employing periodic vertical vibration. The variations in the contact angle and internal volume of the droplet as it evaporates is observed by using a combination of continuous light and a still camera. With regard to the internal velocity, the particle image velocimetry system is applied to visualize the internal thermal Marangoni flow. In order to estimate the internal temperature gradient and surface tension on the surface of a droplet, the theoretical model based on the conduction and convection theory of heat transfer is applied. Thus, the internal velocity increases with an increase in plate temperature. The flow directions of the Marangoni and gravitational flows are opposite, and hence, it may be possible to control the coffee stain effect.

  19. Tail dependence and information flow: Evidence from international equity markets

    Science.gov (United States)

    Al Rahahleh, Naseem; Bhatti, M. Ishaq; Adeinat, Iman

    2017-05-01

    Bhatti and Nguyen (2012) used the copula approach to measure the tail dependence between a number of international markets. They observed that some country pairs exhibit only left-tail dependence whereas others show only right-tail. However, the flow of information from uni-dimensional (one-tail) to bi-dimensional (two-tails) between various markets was not accounted for. In this study, we address the flow of information of this nature by using the dynamic conditional correlation (DCC-GARCH) model. More specifically, we use various versions of the DCC models to explain the nexus between the information flow of international equity and to explain the stochastic forward vs. backward dynamics of financial markets based on data for a 15-year period comprising 3,782 observations. We observed that the information flow between the US and Hong Kong markets and between the US and Australian markets are bi-directional. We also observed that the DCC model captures a wider co-movement structure and inter-connectedness compared to the symmetric Joe-Clayton copula.

  20. ARE INTERNATIONAL TRADE FLOWS A VECTOR OF GLOBALIZATION?

    Directory of Open Access Journals (Sweden)

    Sebastian-Florian ENEA

    2015-10-01

    Full Text Available International commerce and regional integration have long been considered key determinants of national development. The purpose of the present paper is to answer the question whether international trade flows are a vector of globalization and economic growth. In order to achieve this, we have conducted panel data analysis on a sample consisting of members from regional economic structures, such as the E.U., NAFTA, MERCOSUR and ASEAN, and covering a time span of 24 years, from 1990 to 2013. The results of the study underline the fact that, on average and taking into account the heterogeneity of the sample, international commerce counts from around 50 % of the annual economic growth. The future research direction will aim to conduct a more thorough analysis, by focusing more on the regional perspective.

  1. International symposium on cavitation and multiphase flow noise - 1986

    International Nuclear Information System (INIS)

    Arndt, R.E.A.; Billet, M.L.; Blake, W.K.

    1986-01-01

    This book presents the papers given at a symposium on multiphase flow and cavitation. Topics considered at the conference included the development of a cavitation-free sodium pump for a breeder reactor, the stochastic behavior (randomness) of acoustic pressure pulses in the near-subcavitating range, cavitation monitoring of two axial-flow hydroturbines, and noise generated by cavitation in orifice plates with some gaseous effects

  2. Effect of Coriolis and centrifugal forces on flow and heat transfer at high rotation number and high density ratio in non orthogonally internal cooling channel

    Directory of Open Access Journals (Sweden)

    Brahim Berrabah

    2017-02-01

    Full Text Available Numerical predictions of three-dimensional flow and heat transfer are performed for a two-pass square channel with 45° staggered ribs in non-orthogonally mode-rotation using the second moment closure model. At Reynolds number of 25,000, the rotation numbers studied were 0, 0.24, 0.35 and 1.00. The density ratios were 0.13, 0.23 and 0.50. The results show that at high buoyancy parameter and high rotation number with a low density ratio, the flow in the first passage is governed by the secondary flow induced by the rotation whereas the secondary flow induced by the skewed ribs was almost distorted. As a result the heat transfer rate is enhanced on both co-trailing and co-leading sides compared to low and medium rotation number. In contrast, for the second passage, the rotation slightly reduces the heat transfer rate on co-leading side at high rotation number with a low density ratio and degrades it significantly on both co-trailing and co-leading sides at high buoyancy parameter compared to the stationary, low and medium rotation numbers. The numerical results are in fair agreement with available experimental data in the bend region and the second passage, while in the first passage were overestimated at low and medium rotation numbers.

  3. Spillover effects of international standards

    DEFF Research Database (Denmark)

    Trifkovic, Neda

    Most studies focus on trade effects and organizational outcomes of international standards, neglecting the effect of standards on employees. Using a two-year matched firm–employee panel dataset, this paper finds that the application of standards improves work conditions in small and medium....... The study reveals unexpected benefits from certification, calling for higher investment in standards....

  4. An integrated internal flow analysis for ramjet propulsion system

    Science.gov (United States)

    Hsieh, Shih-Yang

    An integrated numerical analysis has been conducted to study the ramjet internal flowfield. Emphasis is placed on the establishment of a unified numerical scheme and accurate representation of the internal flow development. The theoretical model is based on the complete conservation equations of mass, momentum, energy, and species concentration, with consideration of finite-rate chemical reactions and variable properties. Turbulence closure is achieved using a low-Reynolds number k-epsilon two-equation model. A new computation procedure capable of treating time-accurate, chemically reacting flows over a wide range of Mach number was developed. This numerical scheme allows for a unified treatment of the entire flowfield in a ramjet engine, including both the supersonic inlet and the combustion chamber. The algorithm is based on scaling the pressure terms in the momentum equations and preconditioning the conservation equations to circumvent numerical difficulties at low Mach numbers. The resulting equations are solved using the lower-upper (LU) factorization method in a fully-coupled manner, with the incorporation of a flux-differencing upwind TVD scheme to achieve high-order spatial accuracy. The transient behavior of the modeled system is preserved through implementation of the dual time-stepping integration technique. Calculations have been carried out for the flowfield in a typical ramjet engine consisting of an axisymmetric mixed-compression supersonic inlet and a coaxial dump combustor. Distinguished shock structures in the forward section of the inlet were clearly captured. The boundary layer thickening and flow separation behind the terminal shock due to shock/boundary-layer interactions and inlet configuration were observed. The mutual coupling between the inlet and combustor was carefully examined. In particular, strong vortices arising from the inlet shock/acoustic and shock/boundary-layer interactions may convect downstream and affect the combustion

  5. Upper internals of PWR with coolant flow separator

    International Nuclear Information System (INIS)

    Chevereau, G.; Heuze, A.

    1989-01-01

    The upper internals for a PWR has a collecting volume for the coolant merging from the core and an apparatus for separating the flow of coolant. This apparatus has a guide for the control rods, a lower plate perforated to allow the coolant through from the core, an upper plate also perforated to allow the coolant through to the collecting volume and a peripheral binding ring joining the two plates. Each guide comprises an envelope without holes and joined perceptibly tight to the plates [fr

  6. Predictors of antegrade flow at internal carotid artery during carotid artery stenting with proximal protection.

    Science.gov (United States)

    Harada, Kei; Kakumoto, Kosuke; Oshikata, Shogo; Fukuyama, Kozo

    2018-06-01

    Carotid artery stenting (CAS) with proximal occlusion effectively prevent distal cerebral embolism by flow arrest at internal carotid artery (ICA); however, the method can expose antegrade flow at ICA due to incomplete flow arrest. The aim of this study was to identify predictors of antegrade flow during CAS with proximal protection. We retrospectively analyzed clinical and angiographic data among 143 lesions treated with CAS with proximal protection by occluding the common carotid artery (CCA) and external carotid artery (ECA). Flow arrest or antegrade flow at ICA was confirmed by contrast injection during proximal protection. Antegrade flow at ICA was observed in 12 lesions (8.4%). Compared with lesions in which flow arrest of ICA was achieved, the diameter of the superior thyroid artery (STA) was significantly larger (2.4 ± 0.34 vs. 1.4 ± 0.68 mm, p protection should be combined with proximal protection for the lesions with antegrade flow to prevent distal migration of the carotid debris.

  7. Separation Dynamics of Controlled Internal Flow in an Adverse Pressure Gradient

    Science.gov (United States)

    Peterson, C. J.; Vukasinovic, B.; Glezer, A.

    2017-11-01

    The effects of fluidic actuation on the dynamic evolution of aggressive internal flow separation is investigated at speeds up to M = 0.4 within a constant-width diffuser branching off of a primary flow duct. It is shown that a spanwise array of fluidic actuators upstream of the separation actively controls the flow constriction (and losses) within the diffuser and consequently the local pressure gradient at its entrance. The effectiveness of the actuation, as may be measured by the increased flow rate that is diverted through the diffuser, scales with its flow rate coefficient. In the presence of actuation (0.7% mass fraction), the mass flow rate in the primary duct increases by 10% while the fraction of the diverted mass flow rate in the diffuser increases by more than 45%. The flow dynamics near separation in the absence and presence of actuation are characterized using high speed particle image velocimetry and analyzed using proper orthogonal and spectral decompositions. In particular, the spectral contents of the incipient boundary layer separation are compared in the absence and presence of actuation with emphasis on the changes in local dynamics near separation as the characteristic cross stream scale of the boundary layer increases with separation delay.

  8. SGS Modeling of the Internal Energy Equation in LES of Supersonic Channel Flow

    Science.gov (United States)

    Raghunath, Sriram; Brereton, Giles

    2011-11-01

    DNS of fully-developed turbulent supersonic channel flows (Reτ = 190) at up to Mach 3 indicate that the turbulent heat fluxes depend only weakly on Mach number, while the viscous dissipation and pressure dilatation do so strongly. Moreover, pressure dilatation makes a significant contribution to the internal energy budget at Mach 3 and higher. The balance between these terms is critical to determining the temperature (and so molecular viscosity) from the internal energy equation and so, in LES of these flows, it is essential to use accurate SGS models for the viscous dissipation and the pressure dilatation. In this talk, we present LES results for supersonic channel flow, using SGS models for these terms that are based on the resolved-scale dilatation, an inverse timescale, and SGS momentum fluxes, which intrinsically represent this Mach number effect.

  9. Oscillation of a rigid catenary riser due to the internal two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Bordalo, Sergio N.; Morooka, Celso K.; Cavalcante, Cesar C.P. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Matt, Cyntia G.C.; Franciss, Ricardo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2008-07-01

    Production of petroleum reservoirs from deep and ultra-deep waters is of paramount importance in Brazil, and several researches are necessary to develop appropriated equipment and risers for those operational conditions. Risers are suspended pipes used to transport the petroleum fluids between the seabed and the floating production unit. The structural flexibility of riser's lines is conferred by its length when compared with the diameter, characterizing it as a slender body. The risers are submitted to large static and dynamic loads originated from its own weight, waves, currents, platform motions and the internal flow. These loadings may threaten, by fatigue, the structural integrity of the system, compromising its useful life, and so they must be considered in the riser's project. There is a large amount of knowledge in the literature about the effects of external loadings on these systems, but the effect of the internal flow remains vastly unexplored. The variation of the flow mass and momentum inside the riser causes a dynamic loading on this system, originating an oscillatory motion. Furthermore, the gas-liquid two-phase flow may assume several flow patterns (bubble, slug, intermittent or annular), each one possessing completely different characteristics. In this work, the influence of the internal flow on the oscillatory motion (whipping motion) of catenary risers is analyzed. To provide a better understanding of this physical phenomenon, a scaled apparatus was designed and built. The material used to manufacture the riser's model was a flexible silicone tube, and air and water were used to simulate the two-phase flow. The instrumentation used to measure the fluids flow rates and the sustaining force at the top of the model was installed in the apparatus. A video acquisition system was used to determine the displacements, and frequency spectrum, of color targets positioned throughout the model, under several flow conditions. The flow patterns

  10. Numerical analysis of the internal flow field in screw centrifugal blood pump based on CFD

    Science.gov (United States)

    Han, W.; Han, B. X.; Y Wang, H.; Shen, Z. J.

    2013-12-01

    As to the impeller blood pump, the high speed of the impeller, the local high shear force of the flow field and the flow dead region are the main reasons for blood damage. The screw centrifugal pump can effectively alleviate the problems of the high speed and the high shear stress for the impeller. The softness and non-destructiveness during the transfer process can effectively reduce the extent of the damage. By using CFD software, the characteristics of internal flow are analyzed in the screw centrifugal pump by exploring the distribution rules of the velocity, pressure and shear deformation rate of the blood when it flows through the impeller and the destructive effects of spiral blades on blood. The results show that: the design of magnetic levitation solves the sealing problems; the design of regurgitation holes solves the problem of the flow dead zone; the magnetic levitated microcirculation screw centrifugal pump can effectively avoid the vortex, turbulence and high shear forces generated while the blood is flowing through the pump. Since the distribution rules in the velocity field, pressure field and shear deformation rate of the blood in the blood pump are comparatively uniform and the gradient change is comparatively small, the blood damage is effectively reduced.

  11. LES of Internal Combustion Engine Flows Using Cartesian Overset Grids

    Directory of Open Access Journals (Sweden)

    Falkenstein Tobias

    2017-11-01

    Full Text Available Accurate computations of turbulent flows using the Large-Eddy Simulation (LES technique with an appropriate SubFilter Scale (SFS model require low artificial dissipation such that the physical energy cascade process is not perturbed by numerical artifacts. To realize this in practical simulations, energy-conserving numerical schemes and high-quality computational grids are needed. If unstructured meshes are used, the latter requirement often makes grid generation for complex geometries very difficult. Structured Cartesian grids offer the advantage that uncertainties in mesh quality are reduced to choosing appropriate resolution. However, two intrinsic challenges of the structured approach are local mesh refinement and representation of complex geometries. In this work, the effectiveness of numerical methods which can be expected to reduce both drawbacks is assessed in engine flows, using a multi-physics inhouse code. The overset grid approach is utilized to arbitrarily combine grid patches of different spacing to a flow domain of complex shape during mesh generation. Walls are handled by an Immersed Boundary (IB method, which is combined with a wall function to treat underresolved boundary layers. A statistically stationary Spark Ignition (SI engine port flow is simulated at Reynolds numbers typical for engine operation. Good agreement of computed and measured integral flow quantities like overall pressure loss and tumble number is found. A comparison of simulated velocity fields to Particle Image Velocimetry (PIV measurement data concludes the validation of the enhanced numerical framework for both mean velocity and turbulent fluctuations. The performance of two SFS models, the dynamic Smagorinsky model with Lagrangian averaging along pathlines and the coherent structure model, is tested on different grids. Sensitivity of pressure loss and tumble ratio to the wall treatment and mesh refinement is presented. It is shown that increased wall

  12. Investigation of the internal behavior in segmented PEMFCs of different flow fields during cold start process

    International Nuclear Information System (INIS)

    Lin, R.; Ren, Y.S.; Lin, X.W.; Jiang, Z.H.; Yang, Z.; Chang, Y.T.

    2017-01-01

    In this study, we have researched the internal behavior in segmented proton exchange membrane fuel cells (PEMFCs) with three different flow fields during cold start process. The change of internal current density and temperature in fuel cells with different flow fields could be obviously shown by the printed circuit board (PCB) technology, and the study shows that the flow field is significant for enhancing the cold start ability and durability. Single serpentine flow field has the best cold start performance, while triple channel serpentine flow field has the best uniformity. It is found that without a robust temperature rising tendency, the cell temperature reaching 0 °C does not definitely mean a successful cold start because the cell temperature might drop down 0 °C again. Polarization curves show that there is almost no performance degradation after successful cold start, but the cell degrades quickly after the failed cold start at −7 °C and −10 °C. Based on these characteristics, we optimized the rapid cold start strategy by using electric heating and make it possible to start up the PEMFC at temperatures down to −20 °C within about 11 min. - Highlights: • Segmented fuel cell were used to record the internal current density and temperature distributions during the cold start. • The effects of flow fields on the PEMFC cold start capacity were evaluated. • The effect of cold start on the performance of fuel cell was evaluated. • An optimized strategy was adopted to improve the cold start capacity.

  13. Influence of biofuels on the internal flow in diesel injector nozzles

    OpenAIRE

    Salvador, F.J.; Martínez López, Jorge; Romero Bauset, José Vicente; Roselló, M.D.

    2011-01-01

    [EN] In this paper, the behavior of the internal nozzle flow of a standard diesel fuel has been compared against a biodiesel fuel (soybean oil) at cavitating and non-cavitating conditions, using a homogeneous equilibrium model. The model takes into account the compressibility of both phases (liquid and vapour) and use a barotropic equation of state which relates pressure and density to calculate the growth of cavitation. Furthermore, turbulence effects have been introduced using a RNG k- ¿ mo...

  14. Flow Boiling and Condensation Experiment (FBCE) for the International Space Station

    Science.gov (United States)

    Mudawar, Issam; O'Neill, Lucas; Hasan, Mohammad; Nahra, Henry; Hall, Nancy; Balasubramaniam, R.; Mackey, Jeffrey

    2016-01-01

    An effective means to reducing the size and weight of future space vehicles is to replace present mostly single-phase thermal management systems with two-phase counterparts. By capitalizing upon both latent and sensible heat of the coolant rather than sensible heat alone, two-phase thermal management systems can yield orders of magnitude enhancement in flow boiling and condensation heat transfer coefficients. Because the understanding of the influence of microgravity on two-phase flow and heat transfer is quite limited, there is an urgent need for a new experimental microgravity facility to enable investigators to perform long-duration flow boiling and condensation experiments in pursuit of reliable databases, correlations and models. This presentation will discuss recent progress in the development of the Flow Boiling and Condensation Experiment (FBCE) for the International Space Station (ISS) in collaboration between Purdue University and NASA Glenn Research Center. Emphasis will be placed on the design of the flow boiling module and on new flow boiling data that were measured in parabolic flight, along with extensive flow visualization of interfacial features at heat fluxes up to critical heat flux (CHF). Also discussed a theoretical model that will be shown to predict CHF with high accuracy.

  15. Thermally radiative three-dimensional flow of Jeffrey nanofluid with internal heat generation and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Shehzad, S.A., E-mail: ali_qau70@yahoo.com [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Abdullah, Z. [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Abbasi, F.M. [Department of Mathematics, Comsats Institute of Information Technology, Islamabad 44000 (Pakistan); Hayat, T. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan)

    2016-01-01

    This research work addresses the three-dimensional hydromagnetic flow of Jeffrey fluid with nanoparticles. Flow is generated by a bidirectional stretching surface. The effects of thermal radiation and internal heat generation are encountered in energy expressions. More realistic convective boundary conditions at the surface are employed instead of constant surface temperature and mass species conditions. Boundary layer assumptions lead to the governing non-linear mathematical model. Resulting equations through momentum, energy and mass species are made dimensionless using suitable variables. The solution expressions of dimensionless velocities, temperature and nanoparticle concentration have been computed for the convergent series solutions. The impacts of interesting parameters on the dimensionless quantities are displayed and interpreted. The values of physical quantities are computed and analyzed. - Highlights: • Three-dimensional hydromagnetic flow of Jeffrey nanofluid is considered. • Brownian motion and thermophoresis effects are encountered. • Heat transfer analysis is performed with thermal radiation. • Results are plotted and visualized.

  16. Structural Changes of International Trade Flows under the Impact of Globalization

    Directory of Open Access Journals (Sweden)

    Anca Dachin

    2006-08-01

    Full Text Available Structural changes of international trade flows indicate modifications in competitiveness of countries, in terms of production, technological upgrading and exports under the pressure of globalization. The paper aims to point out sources of competitive advantages especially in manufacturing exports of different groups of countries. The focus is on the shifts in the structure of manufacturing in the European Union and their effects on international rankings in export performances. An important issue refers to the opportunities given by the enlargement of the European Union and their impact on EU trade structures.

  17. Internal friction, microstructure, and radiation effects

    International Nuclear Information System (INIS)

    Wechsler, M.S.; Sommer, W.F.; Davidson, D.R.

    1984-01-01

    A brief review is given of internal friction relaxation peaks and background internal friction. The microstructural origin of the internal friction is discussed. Particular emphasis is placed on radiation effects

  18. Flow Visualization of Forced and Natural Convection in Internal Cavities

    International Nuclear Information System (INIS)

    Crepeau, John; Mcllroy, Hugh M. Jr.; McEligot, Donald M.; Condie, Keith G.; McCreery, Glenn; Clarsean, Randy; Brodkey, Robert S.; Guezennec, Yann G.

    2002-01-01

    The report describes innovative flow visualization techniques, fluid mechanics measurements and computational models of flows in a spent nuclear fuel canister. The flow visualization methods used a fluid that reacted with a metal plate to show how a local reaction affects the surrounding flow. A matched index of refraction facility was used to take mean flow and turbulence measurements within a generic spent nuclear fuel canister. Computational models were also made of the flow in the canister. It was determined that the flow field in the canister was very complex, and modifications may need to be made to ensure that the spent fuel elements are completely passivated

  19. Flow Visualization of Forced and Natural Convection in Internal Cavities

    Energy Technology Data Exchange (ETDEWEB)

    John Crepeau; Hugh M. Mcllroy,Jr.; Donald M. McEligot; Keith G. Condie; Glenn McCreery; Randy Clarsean; Robert S. Brodkey; Yann G. Guezennec

    2002-01-31

    The report descries innovative flow visualization techniques, fluid mechanics measurements and computational models of flows in a spent nuclear fuel canister. The flow visualization methods used a fluid that reacted with a metal plate to show how a local reaction affects the surrounding flow. A matched index of refraction facility was used to take mean flow and turbulence measurements within a generic spent nuclear fuel canister. Computational models were also made of the flow in the canister. It was determined that the flow field in the canister was very complex, and modifications may need to be made to ensure that the spent fuel elements are completely passivated.

  20. Internal-external flow integration for a thin ejector-flapped wing section

    Science.gov (United States)

    Woolard, H. W.

    1979-01-01

    Thin airfoil theories of an ejector flapped wing section are reviewed. The global matching of the external airfoil flow with the ejector internal flow and the overall ejector flapped wing section aerodynamic performance are examined. Mathematical models of the external and internal flows are presented. The delineation of the suction flow coefficient characteristics are discussed. The idealized lift performance of an ejector flapped wing relative to a jet augmented flapped wing are compared.

  1. Performance and Internal Flow of a Dental Air Turbine Handpiece

    Directory of Open Access Journals (Sweden)

    Yasuyuki Nishi

    2018-01-01

    Full Text Available An air turbine handpiece is a dental abrasive device that rotates at high speed and uses compressed air as the driving force. It is characterized by its small size, light weight, and painless abrading due to its high-speed rotation, but its torque is small and noise level is high. Thus, to improve the performance of the air turbine handpiece, we conducted a performance test of an actual handpiece and a numerical analysis that modeled the whole handpiece; we also analyzed the internal flow of the handpiece. Results show that experimental and calculated values were consistent for a constant speed load method with the descending speed of 1 mm/min for torque and turbine output. When the tip of the blade was at the center of the nozzle, the torque was at its highest. This is likely because the jet from the nozzle entered the tip of the blade from a close distance that would not reduce the speed and exited along the blade.

  2. Feasibility analysis of large length-scale thermocapillary flow experiment for the International Space Station

    Science.gov (United States)

    Alberts, Samantha J.

    The investigation of microgravity fluid dynamics emerged out of necessity with the advent of space exploration. In particular, capillary research took a leap forward in the 1960s with regards to liquid settling and interfacial dynamics. Due to inherent temperature variations in large spacecraft liquid systems, such as fuel tanks, forces develop on gas-liquid interfaces which induce thermocapillary flows. To date, thermocapillary flows have been studied in small, idealized research geometries usually under terrestrial conditions. The 1 to 3m lengths in current and future large tanks and hardware are designed based on hardware rather than research, which leaves spaceflight systems designers without the technological tools to effectively create safe and efficient designs. This thesis focused on the design and feasibility of a large length-scale thermocapillary flow experiment, which utilizes temperature variations to drive a flow. The design of a helical channel geometry ranging from 1 to 2.5m in length permits a large length-scale thermocapillary flow experiment to fit in a seemingly small International Space Station (ISS) facility such as the Fluids Integrated Rack (FIR). An initial investigation determined the proposed experiment produced measurable data while adhering to the FIR facility limitations. The computational portion of this thesis focused on the investigation of functional geometries of fuel tanks and depots using Surface Evolver. This work outlines the design of a large length-scale thermocapillary flow experiment for the ISS FIR. The results from this work improve the understanding thermocapillary flows and thus improve technological tools for predicting heat and mass transfer in large length-scale thermocapillary flows. Without the tools to understand the thermocapillary flows in these systems, engineers are forced to design larger, heavier vehicles to assure safety and mission success.

  3. A Study Demonstrating the Quantitative Relationship Between Internal Thoracic Artery Length and Free Flow.

    Science.gov (United States)

    Gode, Safa; Sen, Onur; Kadirogulları, Ersin; Reyhancan, Adem; Kyaruzi, Mugisha; Satılmısoglu, Muhammet Hulusi; Erkanlı, Korhan

    2017-08-09

    The left internal thoracic artery (LITA) is the most commonly used arterial bypass conduit in coronary artery bypass graft (CABG) patients and inadequate LITA flow can result in an increase in morbidity and mortality. In this study, we evaluated the effect of excision of the distal spasmodic segment of the LITA on the free flow in CABG patients. This study consisted of 47 patients who underwent elective CABG performed with or without other cardiac surgery, between July 2015 and December 2015. Excised LITA length was shorter than 15mm in group 1, between 15mm and 30mm in group 2 and longer than 30mm in group 3. Left ITA free flow was measured for 60seconds into a container before and after the distal LITA excision. The inter-measurement differences were calculated for the three groups. Thereafter, the comparison was performed in terms of free flow difference amongst the three groups. The mean difference of LITA free flow was 27.6±22.7ml/minute in group 1, 35.4±26.7ml/minute in group 2, and 52.6±26.1ml/minute in group 3. There were significant differences in terms of free flow difference between the groups (p=0.008). Also, differences were statistically significant in group 1 versus group 3 (p=0.003) and group 2 versus group 3 (p=0.038) in the intergroup comparisons. The distal part of the LITA has more spasmodic potential than other segments. This spasm may result in low flow of LITA grafts. Therefore, an as long as possible excision of the distal LITA segment may be required to avoid the spasmodic effect. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  4. Homogeneous internal wave turbulence driven by tidal flows

    Science.gov (United States)

    Le Reun, Thomas; Favier, Benjamin; Le Bars, Michael; Erc Fludyco Team

    2017-11-01

    We propose a novel investigation of the stability of strongly stratified planetary fluid layers undergoing periodic tidal distortion in the limit where rotational effects are negligible compared to buoyancy. With the help of a local model focusing on a small fluid area compared to the global layer, we find that periodic tidal distortion drives a parametric subharmonic resonance of internal. This instability saturates into an homogeneous internal wave turbulence pervading the whole fluid interior: the energy is injected in the unstable waves which then feed a succession of triadic resonances also generating small spatial scales. As the timescale separation between the forcing and Brunt-Väisälä is increased, the temporal spectrum of this turbulence displays a -2 power law reminiscent of the Garrett and Munk spectrum measured in the oceans (Garett & Munk 1979). Moreover, in this state consisting of a superposition of waves in weak non-linear interaction, the mixing efficiency is increased compared to classical, Kolmogorov-like stratified turbulence. This study is of wide interest in geophysical fluid dynamics ranging from oceanic turbulence and tidal heating in icy satellites to dynamo action in partially stratified planetary cores as it could be the case in the Earth. We acknowledge support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 681835-FLUDYCO-ERC-2015-CoG).

  5. Internal Flow Analysis of Large L/D Solid Rocket Motors

    Science.gov (United States)

    Laubacher, Brian A.

    2000-01-01

    Traditionally, Solid Rocket Motor (SRM) internal ballistic performance has been analyzed and predicted with either zero-dimensional (volume filling) codes or one-dimensional ballistics codes. One dimensional simulation of SRM performance is only necessary for ignition modeling, or for motors that have large length to port diameter ratios which exhibit an axial "pressure drop" during the early burn times. This type of prediction works quite well for many types of motors, however, when motor aspect ratios get large, and port to throat ratios get closer to one, two dimensional effects can become significant. The initial propellant grain configuration for the Space Shuttle Reusable Solid Rocket Motor (RSRM) was analyzed with 2-D, steady, axi-symmetric computational fluid dynamics (CFD). The results of the CFD analysis show that the steady-state performance prediction at the initial burn geometry, in general, agrees well with 1-D transient prediction results at an early time, however, significant features of the 2-D flow are captured with the CFD results that would otherwise go unnoticed. Capturing these subtle differences gives a greater confidence to modeling accuracy, and additional insight with which to model secondary internal flow effects like erosive burning. Detailed analysis of the 2-D flowfield has led to the discovery of its hidden 1-D isentropic behavior, and provided the means for a thorough and simplified understanding of internal solid rocket motor flow. Performance parameters such as nozzle stagnation pressure, static pressure drop, characteristic velocity, thrust and specific impulse are discussed in detail and compared for different modeling and prediction methods. The predicted performance using both the 1-D codes and the CFD results are compared with measured data obtained from static tests of the RSRM. The differences and limitations of predictions using ID and 2-D flow fields are discussed and some suggestions for the design of large L/D motors and

  6. The Flow of International Students from a Macro Perspective: A Network Analysis

    Science.gov (United States)

    Barnett, George A.; Lee, Moosung; Jiang, Ke; Park, Han Woo

    2016-01-01

    This paper provides a network analysis of the international flow of students among 210 countries and the factors determining the structure of this flow. Among these factors, bilateral hyperlink connections between countries and the number of telephone minutes (communication variables) are the most important predictors of the flow's structure,…

  7. New international economic order and flow of science and technology

    Energy Technology Data Exchange (ETDEWEB)

    Bojko, B

    1979-12-01

    The role of science and technology in creating a new international economic order based on manpower and raw materials is examined. The traditional linkage of science and politics should end and emphasis be given to increasing productivity in order to expand employment opportunities and raise the world living standard. An indigenous research and development capability is seen as essential to counteract the effects of the time factor when technology is introduced into developing countries. Other considerations are risk of an illusory self-reliance, allocation of development sites in terms of labor substitution, ruthlessness of labor competition during modernization, variations of labor quality, and relationship of demography and unemployment. Competition between the capitalist and socialist countries is being redirected into cooperation in the area of technology transfer. 7 references. (DCK)

  8. Streamwise-body-force-model for rapid simulation combining internal and external flow fields

    Directory of Open Access Journals (Sweden)

    Cui Rong

    2016-10-01

    Full Text Available A streamwise-body-force-model (SBFM is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The validation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.

  9. Internal and external 2-d boundary layer flows

    Science.gov (United States)

    Crawford, M. E.; Kays, W. M.

    1978-01-01

    Computer program computes general two dimensional turbulent boundary-layer flow using finite-difference techniques. Structure allows for user modification to accommodate unique problems. Program should prove useful in many applications where accurate boundary-layer flow calculations are required.

  10. Effectiveness of Nigeria's international obligations in curbing ...

    African Journals Online (AJOL)

    Effectiveness of Nigeria's international obligations in curbing domestic violence. ... Nnamdi Azikiwe University Journal of International Law and Jurisprudence ... This paper examines the issue of domestic violence in Nigeria to determine the ...

  11. CFD simulation of an internal spin-filter: evidence of lateral migration and exchange flow through the mesh.

    Science.gov (United States)

    Figueredo-Cardero, Alvio; Chico, Ernesto; Castilho, Leda R; Medronho, Ricardo A

    2009-11-01

    In the present work Computational Fluid Dynamics (CFD) was used to study the flow field and particle dynamics in an internal spin-filter (SF) bioreactor system. Evidence of a radial exchange flow through the filter mesh was detected, with a magnitude up to 130-fold higher than the perfusion flow, thus significantly contributing to radial drag. The exchange flow magnitude was significantly influenced by the filter rotation rate, but not by the perfusion flow, within the ranges evaluated. Previous reports had only given indirect evidences of this exchange flow phenomenon in spin-filters, but the current simulations were able to quantify and explain it. Flow pattern inside the spin-filter bioreactor resembled a typical Taylor-Couette flow, with vortices being formed in the annular gap and eventually penetrating the internal volume of the filter, thus being the probable reason for the significant exchange flow observed. The simulations also showed that cells become depleted in the vicinity of the mesh due to lateral particle migration. Cell concentration near the filter was approximately 50% of the bulk concentration, explaining why cell separation achieved in SFs is not solely due to size exclusion. The results presented indicate the power of CFD techniques to study and better understand spin-filter systems, aiming at the establishment of effective design, operation and scale-up criteria.

  12. Cultural Factors in the Flow of International News: A Review of the Literature

    Directory of Open Access Journals (Sweden)

    Sakurai Takuya

    2017-01-01

    Full Text Available This paper offers a review of the literature of international news flow, and surveys how the previous studies have attempted to capture “cultural factors” influencing the flow. The factors are grouped into four types of variables: language, former colonial tie, ethnicity, and geographical proximity. This paper argues that cultural factors cannot be significant without economic interests in the era of post-Cold War, that the structure of international news is imbalanced because a few powerful countries dominate the international news market, and that international news reduces cultural varieties to the singular international realities disseminated by the media of such countries.

  13. Internal Benchmarking for Institutional Effectiveness

    Science.gov (United States)

    Ronco, Sharron L.

    2012-01-01

    Internal benchmarking is an established practice in business and industry for identifying best in-house practices and disseminating the knowledge about those practices to other groups in the organization. Internal benchmarking can be done with structures, processes, outcomes, or even individuals. In colleges or universities with multicampuses or a…

  14. 14 CFR 1203.304 - Internal effect.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Internal effect. 1203.304 Section 1203.304... Classification Principles and Considerations § 1203.304 Internal effect. The effect of security protection on... effects and added costs inherent in a security classification must be assessed in light of the detrimental...

  15. Study on Gas-liquid Falling Film Flow in Internal Heat Integrated Distillation Column

    Science.gov (United States)

    Liu, Chong

    2017-10-01

    Gas-liquid internally heat integrated distillation column falling film flow with nonlinear characteristics, study on gas liquid falling film flow regulation control law, can reduce emissions of the distillation column, and it can improve the quality of products. According to the distribution of gas-liquid mass balance internally heat integrated distillation column independent region, distribution model of heat transfer coefficient of building internal heat integrated distillation tower is obtained liquid distillation falling film flow in the saturated vapour pressure of liquid water balance, using heat transfer equation and energy equation to balance the relationship between the circulating iterative gas-liquid falling film flow area, flow parameter information, at a given temperature, pressure conditions, gas-liquid flow falling film theory makes the optimal parameters to achieve the best fitting value with the measured values. The results show that the geometric gas-liquid internally heat integrated distillation column falling film flow heat exchange area and import column thermostat, the average temperature has significant. The positive correlation between the heat exchanger tube entrance due to temperature difference between inside and outside, the heat flux is larger, with the increase of internal heat integrated distillation column temperature, the slope decreases its temperature rise, which accurately describes the internal gas-liquid heat integrated distillation tower falling film flow regularity, take appropriate measures to promote the enhancement of heat transfer. It can enhance the overall efficiency of the heat exchanger.

  16. Analysis of natural convection heat transfer and flows in internally heated stratified liquid pools

    International Nuclear Information System (INIS)

    Gubaidullin, A.A. Jr.; Dinh, T.N.; Sehgal, B.R.

    1999-01-01

    In this paper, natural convection flows and heat transfer in a liquid pool, with two superposed immiscible fluid layers, are analyzed. The objective of the study is to examine the effect of interfacial hydrodynamics and to develop a method which enables energy splitting to be evaluated in a stratified liquid pool. The thermal convection, with and without an internal heat source, in a rectangular cavity with different pairs of fluids was numerically simulated by a CFD code FLOW-3D. It was found that the code performs very well for prediction of heat transfer coefficients for different conditions. The hydrodynamic coupling between immiscible layers was found to have minor, if any, impact on the natural convection heat transfer for the conditions examined. Calculated results were used to develop, and validate, a new correlation for energy splitting and for heat transfer in stratified liquid pools

  17. Mathematical model for the calculation of internal turbulent flow

    International Nuclear Information System (INIS)

    Nicolau, V. de P.; Valle Pereira Filho, H. do

    1981-01-01

    The Navier-Stokes and the turbulent kinetic energy equations for the incompressible, turbulent and fully developed pipe flow, were solved by a finite difference procedure. The distributions of the mean velocity, turbulent shear stress and turbulent kinetic energy were obtained at different Reynolds numbers. Those numerical results were compared with experimental data and the agreement was good in whole cross section of the flow. (Author) [pt

  18. Internal and External Flow over Laser-Textured Superhydrophobic Polytetrafluoroethylene (PTFE).

    Science.gov (United States)

    Ahmmed, K M Tanvir; Patience, Christian; Kietzig, Anne-Marie

    2016-10-12

    In this work, internal and external flows over superhydrophobic (SH) polytetrafluoroethylene (PTFE) were studied. The SH surface was fabricated by a one-step femtosecond laser micromachining process. The drag reduction ability of the textured surface was studied experimentally both in microscale and macroscale internal flows. The slip length, which indicates drag reduction in fluid flow, was determined in microscale fluid flow with a cone-and-plate rheometer, whereas a pressure channel setup was used for macroscale flow experiments. The textured PTFE surface reduced drag in both experiments yielding comparable slip lengths. Moreover, the experimentally obtained slip lengths correspond well to the result obtained applying a semianalytical model, which considers the solid fraction of the textured surface. In addition to the internal flow studies, we fabricated SH PTFE spheres to test their drag reduction abilities in an external flow experiment, where the terminal velocities of the falling spheres were measured. These experiments were conducted at three different Reynolds numbers in both viscous and inertial flow regimes with pure glycerol, a 30% glycerol solution, and water. Surprisingly, the drag on the SH spheres was higher than the measured drag on the non-SH spheres. We hypothesize that the increase in form drag outweighs the decrease in friction drag on the SH sphere. Thus, the overall drag increased. These experiments demonstrate that a superhydrophobic surface that reduces drag in internal flow might not reduce drag in external flow.

  19. Effect of Equilibrium Flow on Plasma Parameters

    International Nuclear Information System (INIS)

    Mukhopadhyay, S.; Lahiri, S.; Sakanaka, P.H.; Dasgupta, B.

    2003-01-01

    The transition to high confinement modes have been identified with the occurrence of strong shear flow near the plasma boundary. Plasma flow has also been associated with various instabilities, heating and other physical processes. As a result, it has become very important to study the effect of such flows on various plasma parameters. In this paper, we present the numerical solution of plasma equilibrium with incompressible toroidal and poloidal flows in several magnetic confinement configurations including tokamaks. The code, which was reported in the last conference, has been used to solve the problem in both circular and D-shaped devices. A parametric study on the generation of shear flow due to radial electric fields has been carried out. Through this study, it has been possible to generate plasma equilibria having sharp pressure gradients which are remarkably close to those reported in various H-mode experiments. The effects of flow on reverse shear equilibria and on the position of the magnetic axis has been studied. Finally, a detailed study has been carried out to understand the effect of flows on important plasma parameters, such as the poloidal flux function, β, energy confinement time

  20. Energy efficiency analyses of active flow aftertreatment systems for lean burn internal combustion engines

    International Nuclear Information System (INIS)

    Zheng Ming; Reader, Graham T.

    2004-01-01

    The use of three way catalytic converters in stoichiometric burn reciprocating internal combustion engine systems has proved to be an effective and efficient method for reducing the level of criteria pollutants. However, such passive systems have not been as successful in emission amelioration when combined with lean burn engines. This is because of the thermochemical nature of the exhaust gases generated by such engines. The high content of exhaust oxygen largely negates the effectiveness of three way catalytic converters, and the comparatively low temperature of the combusted gases means that supplemental energy has to be added to these gases to enable the converter to function correctly. This requirement severely reduces the energy efficiency of conventional passive aftertreatment systems. However, initial empirical studies have indicated that a possible means of improving the performance of aftertreatment devices when used with lean burn engine systems is to use active flow control of the exhaust gases. These results are reported in this paper. This concept has been further investigated by developing an energy efficiency analysis that enables the effects on aftertreatment performance of different gas flow rates, flow reversal frequencies and monolith solid properties to be investigated. Simulation results indicate that through active thermal management, the supplemental energy consumption can be drastically reduced

  1. Toroidal equilibrium states with reversed magnetic shear and parallel flow in connection with the formation of Internal Transport Barriers

    Science.gov (United States)

    Kuiroukidis, Ap.; Throumoulopoulos, G. N.

    2015-08-01

    We construct nonlinear toroidal equilibria of fixed diverted boundary shaping with reversed magnetic shear and flows parallel to the magnetic field. The equilibria have hole-like current density and the reversed magnetic shear increases as the equilibrium nonlinearity becomes stronger. Also, application of a sufficient condition for linear stability implies that the stability is improved as the equilibrium nonlinearity correlated to the reversed magnetic shear gets stronger with a weaker stabilizing contribution from the flow. These results indicate synergetic stabilizing effects of reversed magnetic shear, equilibrium nonlinearity and flow in the establishment of Internal Transport Barriers (ITBs).

  2. Effect of gas quantity on two-phase flow characteristics of a mixed-flow pump

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2016-04-01

    Full Text Available The inlet gas quantity has a great influence on the performance and inner flow characteristics of a mixed-flow pump. In this article, both numerical and experimental methods are used to carry out this research work. The effects under the steady gas volume fraction state and the transient gas quantity variation process on the mixed-flow pump are investigated and compared in detail. It could be concluded that the head of the mixed-flow pump shows slight decline at the low gas volume fraction state, while it decreases sharply at the high gas volume fraction state and then decreases with the increasing gas quantity. There is an obvious asymmetric blade vapor density on the blade suction side under each cavitation state. The cavities can be weakened obviously by increasing the inlet gas volume fraction within a certain range. It has little influence on the internal unsteady flow of the mixed-flow pump when the gas volume fraction is less than 10%, but the pump starts to operate with a great unsteady characteristic when the inlet gas volume fraction increases to 15%.

  3. Pressure Effect on Entrance Flow

    DEFF Research Database (Denmark)

    Christensen, Jens Horslund; Couch, Mark

    1997-01-01

    The paper reports on experimentally determined pressure drops associated with orifice and capillary dies, where the exit pressure is elevated. The effect of hydrostatic pressure up to 70 MPa is reported for PS, LDPE and PP melts.......The paper reports on experimentally determined pressure drops associated with orifice and capillary dies, where the exit pressure is elevated. The effect of hydrostatic pressure up to 70 MPa is reported for PS, LDPE and PP melts....

  4. Large-eddy simulations of turbulent flows in internal combustion engines

    Science.gov (United States)

    Banaeizadeh, Araz

    The two-phase compressible scalar filtered mass density function (FMDF) model is further developed and employed for large-eddy simulations (LES) of turbulent spray combustion in internal combustion (IC) engines. In this model, the filtered compressible Navier-Stokes equations are solved in a generalized curvilinear coordinate system with high-order, multi-block, compact differencing schemes for the turbulent velocity and pressure. However, turbulent mixing and combustion are computed with a new two-phase compressible scalar FMDF model. The spray and droplet dispersion/evaporation are modeled with a Lagrangian method. A new Lagrangian-Eulerian-Lagrangian computational method is employed for solving the flow, spray and scalar equation. The pressure effect in the energy equation, as needed in compressible flows, is included in the FMDF formulation. The performance of the new compressible LES/FMDF model is assessed by simulating the flow field and scalar mixing in a rapid compression machine (RCM), in a shock tube and in a supersonic co-axial jet. Consistency of temperatures predicted by the Eulerian finite-difference (FD) and Lagrangian Monte Carlo (MC) parts of the LES/FMDF model are established by including the pressure on the FMDF. It is shown that the LES/FMDF model is able to correctly capture the scalar mixing in both compressible subsonic and supersonic flows. Using the new two-phase LES/FMDF model, fluid dynamics, heat transfer, spray and combustion in the RCM with flat and crevice piston are studied. It is shown that the temperature distribution in the RCM with crevice piston is more uniform than the RCM with flat piston. The fuel spray characteristics and the spray parameters affecting the fuel mixing inside the RCM in reacting and non-reacting flows are also studied. The predicted liquid penetration and flame lift-off lengths for respectively non-reacting and reacting sprays are found to compare well with the available experimental data. Temperatures and

  5. Measuring the effectiveness of international environmental regimes

    Energy Technology Data Exchange (ETDEWEB)

    Helm, C.; Sprinz, D.F.

    1999-05-01

    While past research has emphasized the importance of international regimes for international governance, systematic assessments of regime effects are missing. This article derives a standardized measurement concept for the effectiveness of international environmental regimes by developing an operational rational choice calculus to evaluate actual policy simultaneously against a non-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement instrument is demonstrated by way of two international treaties regulating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects - but fall substantially short of the collective optima. (orig.)

  6. Assessment of turbulent flow effects on the vessel wall using four-dimensional flow MRI.

    Science.gov (United States)

    Ziegler, Magnus; Lantz, Jonas; Ebbers, Tino; Dyverfeldt, Petter

    2017-06-01

    To explore the use of MR-estimated turbulence quantities for the assessment of turbulent flow effects on the vessel wall. Numerical velocity data for two patient-derived models was obtained using computational fluid dynamics (CFD) for two physiological flow rates. The four-dimensional (4D) Flow MRI measurements were simulated at three different spatial resolutions and used to investigate the estimation of turbulent wall shear stress (tWSS) using the intravoxel standard deviation (IVSD) of velocity and turbulent kinetic energy (TKE) estimated near the vessel wall. Accurate estimation of tWSS using the IVSD is limited by the spatial resolution achievable with 4D Flow MRI. TKE, estimated near the wall, has a strong linear relationship to the tWSS (mean R 2  = 0.84). Near-wall TKE estimates from MR simulations have good agreement to CFD-derived ground truth (mean R 2  = 0.90). Maps of near-wall TKE have strong visual correspondence to tWSS. Near-wall estimation of TKE permits assessment of relative maps of tWSS, but direct estimation of tWSS is challenging due to limitations in spatial resolution. Assessment of tWSS and near-wall TKE may open new avenues for analysis of different pathologies. Magn Reson Med 77:2310-2319, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  7. The internal flow pattern analysis of a tidal power turbine operating on bidirectional generation-pumping

    International Nuclear Information System (INIS)

    Luo, Y Y; Xiao, Y X; Wang, Z W

    2013-01-01

    Using tidal energy can reduce environment pollution, save conventional energy and improve energy structure, hence it presents great advantage and is developing potential. Influenced by flood tide and low tide, a fully functional tidal power station needs to experience six operating modes, including bidirectional generation, pumping and sluice; the internal unsteady flow pattern and dynamic characters are very complicated. Based on a bidirectional tidal generator unit, three-dimensional unsteady flows in the flow path were calculated for four typical operating conditions with the pressure pulsation characteristics analyzed. According to the numerical results, the internal flow characteristics in the flow path were discussed. The influence of gravity to the hydraulic performance and flow characteristics were analysed. The results provide a theoretical analysis method of the hydraulic optimization design of the same type unit as well as a direction for stable operation and optimal scheduling of existing tidal power unit

  8. Analysis of forecasting methods of cargo flows in International transportation by land transport

    OpenAIRE

    Ponomareva, N.

    2005-01-01

    Advantages and disadvantages of the existing forecasting methods of cargo flows are presented. The improvement of cargo flows forecasting method in international transportation by land transport is considered on the basis of a interregional balance model to get more correct and fuller forecast.

  9. A semi-elliptic analysis of internal viscous flows

    International Nuclear Information System (INIS)

    Ghia, U.; Ramamurti, R.; Ghia, K.N.

    1986-01-01

    The increased demands placed presently on the performance of compressors and turbines of gas-turbine engines have, for some time, pointed the need for accurate analysis of viscous flows in turbomachinery. With the recent developments of advanced computational facilities, much effort has been made to respond to this need. Various mathematical formulations, grid systems and numerical techniques have been developed for the numerical solution of the viscous flow equations (Refs. 1-4). The full Navier-Stokes equations as well as their corresponding thin-layer approximate form have been employed in H- as well as C-grids, using explicit or implicit methods, including convergence enhancement techniques based on multi-grid methodology. Nevertheless, obtaining converged solutions for general geometries on acceptably refined grids remains a computationally demanding task. The present paper discusses a reduced form on the governing equations which can capture much of the physics, while requiring less computer resources than the full Navier-Stokes equations

  10. Numerical simulation of magnetohydrodynamic (MHD) flow with internal heat generation

    International Nuclear Information System (INIS)

    Bokade, Vipin; Bhandarkar, U.V.; Bodi, Kowsik

    2016-01-01

    A strong magnetic field is used to confine the plasma in a fusion reactor. This magnetic field also affects the flow of Lead-Lithium (breeder/coolant) in the breeding blanket. So it is important to study MHD flow of Lead-Lithium (Pb-Li). Open-source toolbox, OpenFOAM, is used to study single phase behaviour of Pb-Li. As the induced magnetic field is very small, Ni et al. electric potential algorithm is employed in OpenFOAM and validated with analytical results. This solver can also solve the temperature field with heat source term. Simulations are carried out in 2D straight channel for various values of Hartmann Number ranging from 100 to 5000 and velocity profile, temperature, current density and pressure drop are studied. (author)

  11. Stability of the n = 1 internal kink mode in equilibria with flows

    International Nuclear Information System (INIS)

    Aydemir, A.Y.; Waelbroeck, F.L.

    1996-01-01

    Stabilizing influence of mass flows, either directly or through their shearing action, on various modes is now generally recognized. Here we examine linear and nonlinear stability of the n = 1 internal kink mode in equilibria with toroidal rotation, using our nonlinear, initial-value MHD code CTD, which can be used to generate self-consistent equilibria with flows in arbitrary geometries. It is well known that equilibrium mass flows introduce complications in determination of MHD equilibria and their stability properties, such as the loss of self-adjointness and an increase in the number of conditions required to uniquely determine the equilibria. Thus, even with purely toroidal flows, an implicit statement about the equation of state is needed, in addition to a knowledge of the magnetic field and velocity profiles; rotation in an adiabatic plasma leads to a different equilibrium than, for example, in an isothermal one, with possibly quite different stability properties. We find that the expected stabilizing influence of toroidal rotation on n = 1 is generally absent in adiabatically generated equilibria in which, of all the relevant thermodynamic variables, only the specific entropy is a flux function, s = s (ψ). Fortunately, physically more relevant isothermal case where the temperature is constant on flux surfaces, T = T(ψ), has more favorable stability characteristics. On the other hand, an inconsistent but common practice of ignoring density perturbations, a benign omission for static equilibria, leads to overly optimistic results when equilibrium flows axe present, predicting stability when there may not be any. The crucial role played by the equation of state in determining equilibrium raises questions regarding the role of parallel transport in stability calculations; this and other nonideal effects, along with the role of plasma β vs. the rotational β, and nonlinear stability when the mode is pushed beyond marginality, will be discussed

  12. A study on the performance and internal flow characteristics of a very low specific speed centrifugal pump

    International Nuclear Information System (INIS)

    Choi, Young Do; Kurokawa, Junichi; Lee, Young Ho

    2005-01-01

    In the very low specific speed range (n s < 0.25, non-dimensional), the efficiency of centrifugal pump designed by a conventional method is very low in common. Therefore, positive-displacement pumps have long been used widely. Recently, since the centrifugal pumps are becoming higher in rotational speed and smaller in size, there experts to develop a new centrifugal pump with a high performance to replace the positive-displacement pumps. The purpose of this study is to investigate the internal flow characteristics of a very low specific speed centrifugal pump and to examine the effect of internal flow pattern on pump performance. The results show that the theoretical head definition of semi-open impeller should be revised by the consideration of high slip factor in the semi-open impeller, and the leakage flow through the tip clearance results in a large effect on the impeller internal flow. Strong reverse flow at the outlet of semi-open impeller reduces the absolute tangential velocity considerably, and the decreased absolute tangential velocity increases the slip factor with the reduction of theoretical head

  13. Soret and Hall effects on unsteady MHD free convection flow of ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... effects on unsteady MHD free convection flow of radiating and chemically reactive fluid ... Expressions for shear stress, rate of heat transfer and rate of mass transfer at the plate ...

  14. Breaking down the silos to decrease internal diversions and patient flow delays.

    Science.gov (United States)

    Driscoll, Molly; Tobis, Kristen; Gurka, David; Serafin, Frederick; Carlson, Elizabeth

    2015-01-01

    Hospitals strive to admit patients to the units where caregiver competencies align with the patient's condition. When the hospital's census peaks, internal diversions and the associated risks increase, which are intensified when silos exist, as segregated care negatively impacts collaboration and patient safety. In this study, a 600+-bed academic, tertiary care specialty hospital experienced an increase in internal diversions. Within the neuroscience service line, emergent neuroscience transfers from outside hospitals had been declined or internally diverted because of capacity limitations. Formalized processes for improving collaboration between health care providers related to capacity issues were required to decrease internal diversions and improve patient flow and patient safety. A pilot project was conducted on neuroscience units during a process improvement initiative. A hospital-wide internal diversion plan was developed, identifying primary and secondary placement options for all patients requiring hospitalization to support patient flow and patient safety. Forecasting tools were developed to provide units' leadership with current information on expected admissions. Daily capacity huddles were instituted to increase collaboration between patient care units. The interventions trialed during the pilot decreased internal diversions and improved patient flow. The improved collaboration resulted in an 80% decrease in declinations of emergent intensive care unit transfers from outside hospitals due to capacity limitations and a 50% decrease in the number of these patients being internally diverted to alternate intensive care units. The interventions implemented minimized internal diversions and improved patient flow. The transparency of the patient placement process led to an increased collaboration between all participants.

  15. Linked migration systems: immigration and internal labor flows in the United States.

    Science.gov (United States)

    R. Walker; M. Ellis; R. Barff

    1992-01-01

    We investigate the relationship between immigration and internal labor movements in the US. Wedding the literatures on immigration and internal migration, we develop a mobility model linking these various flows on the basis of occupational status of worker, producction and institutional relations in the economy, and economic restructuring.

  16. Internal air flow analysis of a bladeless micro aerial vehicle hemisphere body using computational fluid dynamic

    Energy Technology Data Exchange (ETDEWEB)

    Othman, M. N. K., E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Zuradzman, M. Razlan, E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Hazry, D., E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Khairunizam, Wan, E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Shahriman, A. B., E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Yaacob, S., E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Ahmed, S. Faiz, E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my [Centre of Excellence for Unmanned Aerial Systems, Universiti Malaysia Perlis, 01000 Kangar, Perlis (Malaysia); and others

    2014-12-04

    This paper explain the analysis of internal air flow velocity of a bladeless vertical takeoff and landing (VTOL) Micro Aerial Vehicle (MAV) hemisphere body. In mechanical design, before produce a prototype model, several analyses should be done to ensure the product's effectiveness and efficiency. There are two types of analysis method can be done in mechanical design; mathematical modeling and computational fluid dynamic. In this analysis, I used computational fluid dynamic (CFD) by using SolidWorks Flow Simulation software. The idea came through to overcome the problem of ordinary quadrotor UAV which has larger size due to using four rotors and the propellers are exposed to environment. The bladeless MAV body is designed to protect all electronic parts, which means it can be used in rainy condition. It also has been made to increase the thrust produced by the ducted propeller compare to exposed propeller. From the analysis result, the air flow velocity at the ducted area increased to twice the inlet air. This means that the duct contribute to the increasing of air velocity.

  17. Internal air flow analysis of a bladeless micro aerial vehicle hemisphere body using computational fluid dynamic

    Science.gov (United States)

    Othman, M. N. K.; Zuradzman, M. Razlan; Hazry, D.; Khairunizam, Wan; Shahriman, A. B.; Yaacob, S.; Ahmed, S. Faiz; Hussain, Abadalsalam T.

    2014-12-01

    This paper explain the analysis of internal air flow velocity of a bladeless vertical takeoff and landing (VTOL) Micro Aerial Vehicle (MAV) hemisphere body. In mechanical design, before produce a prototype model, several analyses should be done to ensure the product's effectiveness and efficiency. There are two types of analysis method can be done in mechanical design; mathematical modeling and computational fluid dynamic. In this analysis, I used computational fluid dynamic (CFD) by using SolidWorks Flow Simulation software. The idea came through to overcome the problem of ordinary quadrotor UAV which has larger size due to using four rotors and the propellers are exposed to environment. The bladeless MAV body is designed to protect all electronic parts, which means it can be used in rainy condition. It also has been made to increase the thrust produced by the ducted propeller compare to exposed propeller. From the analysis result, the air flow velocity at the ducted area increased to twice the inlet air. This means that the duct contribute to the increasing of air velocity.

  18. Internal air flow analysis of a bladeless micro aerial vehicle hemisphere body using computational fluid dynamic

    International Nuclear Information System (INIS)

    Othman, M. N. K.; Zuradzman, M. Razlan; Hazry, D.; Khairunizam, Wan; Shahriman, A. B.; Yaacob, S.; Ahmed, S. Faiz

    2014-01-01

    This paper explain the analysis of internal air flow velocity of a bladeless vertical takeoff and landing (VTOL) Micro Aerial Vehicle (MAV) hemisphere body. In mechanical design, before produce a prototype model, several analyses should be done to ensure the product's effectiveness and efficiency. There are two types of analysis method can be done in mechanical design; mathematical modeling and computational fluid dynamic. In this analysis, I used computational fluid dynamic (CFD) by using SolidWorks Flow Simulation software. The idea came through to overcome the problem of ordinary quadrotor UAV which has larger size due to using four rotors and the propellers are exposed to environment. The bladeless MAV body is designed to protect all electronic parts, which means it can be used in rainy condition. It also has been made to increase the thrust produced by the ducted propeller compare to exposed propeller. From the analysis result, the air flow velocity at the ducted area increased to twice the inlet air. This means that the duct contribute to the increasing of air velocity

  19. Testing and Performance Verification of a High Bypass Ratio Turbofan Rotor in an Internal Flow Component Test Facility

    Science.gov (United States)

    VanZante, Dale E.; Podboy, Gary G.; Miller, Christopher J.; Thorp, Scott A.

    2009-01-01

    A 1/5 scale model rotor representative of a current technology, high bypass ratio, turbofan engine was installed and tested in the W8 single-stage, high-speed, compressor test facility at NASA Glenn Research Center (GRC). The same fan rotor was tested previously in the GRC 9x15 Low Speed Wind Tunnel as a fan module consisting of the rotor and outlet guide vanes mounted in a flight-like nacelle. The W8 test verified that the aerodynamic performance and detailed flow field of the rotor as installed in W8 were representative of the wind tunnel fan module installation. Modifications to W8 were necessary to ensure that this internal flow facility would have a flow field at the test package that is representative of flow conditions in the wind tunnel installation. Inlet flow conditioning was designed and installed in W8 to lower the fan face turbulence intensity to less than 1.0 percent in order to better match the wind tunnel operating environment. Also, inlet bleed was added to thin the casing boundary layer to be more representative of a flight nacelle boundary layer. On the 100 percent speed operating line the fan pressure rise and mass flow rate agreed with the wind tunnel data to within 1 percent. Detailed hot film surveys of the inlet flow, inlet boundary layer and fan exit flow were compared to results from the wind tunnel. The effect of inlet casing boundary layer thickness on fan performance was quantified. Challenges and lessons learned from testing this high flow, low static pressure rise fan in an internal flow facility are discussed.

  20. Internal Flow of a High Specific-Speed Diagonal-Flow Fan (Rotor Outlet Flow Fields with Rotating Stall

    Directory of Open Access Journals (Sweden)

    Norimasa Shiomi

    2003-01-01

    Full Text Available We carried out investigations for the purpose of clarifying the rotor outlet flow fields with rotating stall cell in a diagonal-flow fan. The test fan was a high–specific-speed (ns=1620 type of diagonal-flow fan that had 6 rotor blades and 11 stator blades. It has been shown that the number of the stall cell is 1, and its propagating speed is approximately 80% of its rotor speed, although little has been known about the behavior of the stall cell because a flow field with a rotating stall cell is essentially unsteady. In order to capture the behavior of the stall cell at the rotor outlet flow fields, hot-wire surveys were performed using a single-slant hotwire probe. The data obtained by these surveys were processed by means of a double phase-locked averaging technique, which enabled us to capture the flow field with the rotating stall cell in the reference coordinate system fixed to the rotor. As a result, time-dependent ensemble averages of the three-dimensional velocity components at the rotor outlet flow fields were obtained. The behavior of the stall cell was shown for each velocity component, and the flow patterns on the meridional planes were illustrated.

  1. Spontaneous generation and reversals of mean flows in a convectively-generated internal gravity wave field

    Science.gov (United States)

    Couston, Louis-Alexandre; Lecoanet, Daniel; Favier, Benjamin; Le Bars, Michael

    2017-11-01

    We investigate via direct numerical simulations the spontaneous generation and reversals of mean zonal flows in a stably-stratified fluid layer lying above a turbulent convective fluid. Contrary to the leading idealized theories of mean flow generation by self-interacting internal waves, the emergence of a mean flow in a convectively-generated internal gravity wave field is not always possible because nonlinear interactions of waves of different frequencies can disrupt the mean flow generation mechanism. Strong mean flows thus emerge when the divergence of the Reynolds stress resulting from the nonlinear interactions of internal waves produces a strong enough anti-diffusive acceleration for the mean flow, which, as we will demonstrate, is the case when the Prandtl number is sufficiently low, or when the energy input into the internal wavefield by the convection and density stratification are sufficiently large. Implications for mean zonal flow production as observed in the equatorial stratospheres of the Earth, Saturn and Jupiter, and possibly occurring in other geophysical systems such as planetary and stellar interiors will be briefly discussed. Funding provided by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program through Grant Agreement No. 681835-FLUDYCO-ERC-2015-CoG.

  2. Radioresistance and immunization effectiveness under internal irradiation

    International Nuclear Information System (INIS)

    Kal'nitskij, S.A.

    1978-01-01

    The effect of preliminary immunization on the radioresistance of mice to internal irradiation from incorporated 137 Cs or 90 Sr was studied, and it was found that a preliminary single immunization with bacterial vaccines had a favorable effect on the outcome of radiation injury. The present results suggested that vaccination had a very pronounced radioprotective effect and so may be used as a means of biologic protection from internal irradiation

  3. Mode pattern of internal flow in a water droplet on a vibrating hydrophobic surface.

    Science.gov (United States)

    Kim, Hun; Lim, Hee-Chang

    2015-06-04

    The objective of this study is to understand the mode pattern of the internal flow in a water droplet placed on a hydrophobic surface that periodically and vertically vibrates. As a result, a water droplet on a vibrating hydrophobic surface has a typical shape that depends on each resonance mode, and, additionally, we observed a diversified lobe size and internal flows in the water droplet. The size of each lobe at the resonance frequency was relatively greater than that at the neighboring frequencies, and the internal flow of the nth order mode was also observed in the flow visualization. In general, large symmetrical flow streams were generated along the vertical axis in each mode, with a large circulating movement from the bottom to the top, and then to the triple contact line along the droplet surface. In contrast, modes 2 and 4 generated a Y-shaped flow pattern, in which the flow moved to the node point in the lower part of the droplet, but modes 6 and 8 had similar patterns, with only a little difference. In addition, as a result of the PIV measurement, while the flow velocity of mode 4 was faster than that of model 2, those of modes 6 and 8 were almost similar.

  4. Scale-model characterization of flow-induced vibrational response of FFTF reactor internals

    International Nuclear Information System (INIS)

    Ryan, J.A.; Mahoney, J.J.

    1980-10-01

    Fast Test Reactor core internal and peripheral components were assessed for flow-induced vibrational characteristics under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup as an integral part of the Fast Test Reactor Vibration Program. The Hydraulic Core Mockup was an 0.285 geometric scale model of the Fast Test Reactor internals designed to simulate prototype vibrational and hydraulic characteristics. Using water to simulate sodium coolant, vibrational characteristics were measured and determined for selected model components over the scaled flow range of 36 to 110%. Additionally, in-situ shaker tests were conducted on selected Hydraulic Core Mockup outlet plenum components to establish modal characteristics. Most components exhibited resonant response at all test flow rates; however, the measured dynamic response was neither abnormal nor anomalously flow-rate dependent, and the predicted prototype components' response were deemed acceptable

  5. A Computational Study of Internal Flows in a Heated Water-Oil Emulsion Droplet

    KAUST Repository

    Sim, Jaeheon

    2015-01-05

    The vaporization characteristics of water-oil emulsion droplets are investigated by high fidelity computational simulations. One of the key objectives is to identify the physical mechanism for the experimentally observed behavior that the component in the dispersed micro-droplets always vaporizes first, for both oil-in-water and water-in-oil emulsion droplets. The mechanism of this phenomenon has not been clearly understood. In this study, an Eulerian-Lagrangian method was implemented with a temperature-dependent surface tension model and a dynamic adaptive mesh refinement in order to effectively capture the thermo-capillary effect of a micro-droplet in an emulsion droplet efficiently. It is found that the temperature difference in an emulsion droplet creates a surface tension gradient along the micro-droplet surface, inducing surface movement. Subsequently, the outer shear flow and internal flow circulation inside the droplet, referred to as the Marangoni convection, are created. The present study confirms that the Marangoni effect can be sufficiently large to drive the micro-droplets to the emulsion droplet surface at higher temperature, for both water-in-oil and oil-and-water emulsion droplets. A further parametric study with different micro-droplet sizes and temperature gradients demonstrates that larger micro-droplets move faster with larger temperature gradient. The oil micro-droplet in oil-in-water emulsion droplets moves faster due to large temperature gradients by smaller thermal conductivity.

  6. Gazprom: internal structure, management principles and financial flows

    International Nuclear Information System (INIS)

    Kryukov, Valery; Moe, Arild.

    1996-01-01

    Gazprom is responsible for over 95% of total Russian natural gas production and is one of the largest companies in the world. As well as being of major importance in the Russian domestic energy balance, it is also the largest gas trader in the world, supplying about half the gas imported into western and east-central Europe. The scale of these external activities means that the terms on which it supplies gas to its customers will have an impact on business beyond the gas industry. This study investigates the roots of the company and analyses its current organisation, management structure and financial flows. The main topics covered are: the Russian gas industry in the Soviet era; the organisational structure of Gazprom after privatisation; pricing policy; the company's financial position; Gazprom in relation to the domestic economy and the outside world. (9 figures; 7 tables). (author)

  7. Total internal reflection effect on gyrotropic interface

    Science.gov (United States)

    Glushchenko, Alexander G.; Glushchenko, Eugene P.; Zhukov, Sergey V.

    2018-02-01

    This article considers the physical features of total internal reflection at gyrotropic and isotropic interfaces for two cases: electrical gyrotropy (plasma) and magnetic gyrotropy (ferrite). It is shown that the plasma magnetization may lead to the formation of the total internal reflection effect, which does not occur in isotropic plasma. The threshold values of the magnetic field, which are necessary for the total internal reflection effect, are determined. The total internal reflection effect on a ferrite-dielectric interface for waves emanating from different angles is observed in various frequency ranges and magnetization fields. The study points out the possibility of changing the total internal reflection angle value in large limits due to a change in the external magnetic field magnitude. The calculation results of the total internal reflection angle dependence on the external magnetic field magnitude are presented. The formulas are elaborated for calculating the total internal reflection angles of different interfaces for gyrotropic and isotropic media. The generalized formulas are defined for calculating the Doppler effect in the gyrotropic media. The study demonstrates how the velocity of the media interface affects the limiting angle of total internal refection.

  8. Cold flow simulation of an internal combustion engine with vertical valves using layering approach

    Science.gov (United States)

    Martinas, G.; Cupsa, O. S.; Stan, L. C.; Arsenie, A.

    2015-11-01

    Complying with emission requirements and fuel consumption efficiency are the points which drive any development of internal combustion engine. Refinement of the process of combustion and mixture formation, together with in-cylinder flow refinement, is a requirement, valves and piston bowl and intake exhaust port design optimization is essential. In order to reduce the time for design optimization cycle it is used Computational Fluid Dynamics (CFD). Being time consuming and highly costly caring out of experiment using flow bench testing this methods start to become less utilized. Air motion inside the intake manifold is one of the important factors, which govern the engine performance and emission of multi-cylinder diesel engines. Any cold flow study on IC is targeting the process of identifying and improving the fluid flow inside the ports and the combustion chamber. This is only the base for an optimization process targeting to increase the volume of air accessing the combustion space and to increase the turbulence of the air at the end of the compression stage. One of the first conclusions will be that the valve diameter is a fine tradeoff between the need for a bigger diameter involving a greater mass of air filling the cylinder, and the need of a smaller diameter in order to reduce the blind zone. Here there is room for optimization studies. The relative pressure indicates a suction effect coming from the moving piston. The more the shape of the inlet port is smoother and the diameter of the piston is bigger, the aerodynamic resistance of the geometry will be smaller so that the difference of inlet port pressure and the pressure near to piston face will be smaller. Here again there is enough room for more optimization studies.

  9. Surface roughness effects on turbulent Couette flow

    Science.gov (United States)

    Lee, Young Mo; Lee, Jae Hwa

    2017-11-01

    Direct numerical simulation of a turbulent Couette flow with two-dimensional (2-D) rod roughness is performed to examine the effects of the surface roughness. The Reynolds number based on the channel centerline laminar velocity (Uco) and channel half height (h) is Re =7200. The 2-D rods are periodically arranged with a streamwise pitch of λ = 8 k on the bottom wall, and the roughness height is k = 0.12 h. It is shown that the wall-normal extent for the logarithmic layer is significantly shortened in the rough-wall turbulent Couette flow, compared to a turbulent Couette flow with smooth wall. Although the Reynolds stresses are increased in a turbulent channel flow with surface roughness in the outer layer due to large-scale ejection motions produced by the 2-D rods, those of the rough-wall Couette flow are decreased. Isosurfaces of the u-structures averaged in time suggest that the decrease of the turbulent activity near the centerline is associated with weakened large-scale counter-rotating roll modes by the surface roughness. This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1A09000537) and the Ministry of Science, ICT & Future Planning (NRF-2017R1A5A1015311).

  10. Internal Nozzle Flow Simulations of Gasoline-Like Fuels under Diesel Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Torelli, R.; Som, S.; Pei, Y.; Zhang, Yu; Traver, Michael

    2017-05-15

    Spray formation in internal combustion engines with direct injection is strictly correlated with internal nozzle flow characteristics, which are in turn influenced by fuel physical properties and injector needle motion. This paper pre-sents a series of 3D simulations that model the in-nozzle flow in a 5-hole mini-sac diesel injector. Two gasoline-like naphtha fuels, namely full-range and light naphtha, were tested under operating conditions typical of diesel applica-tions and were compared with n-dodecane, selected from a palette used as diesel surrogates. Validated methodolo-gies from our previous work were employed to account for realistic needle motion. The multi-phase nature of the problem was described by the mixture model assumption with the Volume of Fluid method. Cavitation effects were included by means of the Homogeneous Relaxation Model and turbulence closure was achieved with the Standard k-ε model in an Unsteady Reynolds-Averaged Navier-Stokes formulation. The results revealed that injector perfor-mance and propensity to cavitation are influenced by the fuel properties. Analyses of several physical quantities were carried out to highlight the fuel-to-fuel differences in terms of mass flow rate, discharge coefficients, and fuel vapor volume fraction inside the orifices. A series of parametric investigations was also performed to assess the fuel response to varied fuel injection temperature, injection pressure, and cross-sectional orifice area. For all cases, the strict correlation between cavitation magnitude and saturation pressure was confirmed. Owing to their higher volatil-ity, the two gasoline-like fuels were characterized by higher cavitation across all the simulated conditions. Occur-rence of cavitation was mostly found at the needle seat and at the orifice inlets during the injection event’s transient, when very small gaps exist between the needle and its seat. This behavior tended to disappear at maximum needle lift, where cavitation was

  11. Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics

    Science.gov (United States)

    LaGraff, John E.; Povinelli, Louis A.; Gostelow, J. Paul; Glauser, Mark

    2010-01-01

    Topics covered include: Flow Physics and control for Internal and External Aerodynamics (not in TOC...starts on pg13); Breaking CFD Bottlenecks in Gas-Turbine Flow-Path Design; Streamwise Vortices on the Convex Surfaces of Circular Cylinders and Turbomachinery Blading; DNS and Embedded DNS as Tools for Investigating Unsteady Heat Transfer Phenomena in Turbines; Cavitation, Flow Structure and Turbulence in the Tip Region of a Rotor Blade; Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows; Active Flow Control of Lifting Surface With Flap-Current Activities and Future Directions; Closed-Loop Control of Vortex Formation in Separated Flows; Global Instability on Laminar Separation Bubbles-Revisited; Very Large-Scale Motions in Smooth and Rough Wall Boundary Layers; Instability of a Supersonic Boundary-Layer With Localized Roughness; Active Control of Open Cavities; Amplitude Scaling of Active Separation Control; U.S. Air Force Research Laboratory's Need for Flow Physics and Control With Applications Involving Aero-Optics and Weapon Bay Cavities; Some Issues Related to Integrating Active Flow Control With Flight Control; Active Flow Control Strategies Using Surface Pressure Measurements; Reduction of Unsteady Forcing in a Vaned, Contra-Rotating Transonic Turbine Configuration; Active Flow Control Stator With Coanda Surface; Controlling Separation in Turbomachines; Flow Control on Low-Pressure Turbine Airfoils Using Vortex Generator Jets; Reduced Order Modeling Incompressible Flows; Study and Control of Flow Past Disk, and Circular and Rectangular Cylinders Aligned in the Flow; Periodic Forcing of a Turbulent Axisymmetric Wake; Control of Vortex Breakdown in Critical Swirl Regime Using Azimuthal Forcing; External and Turbomachinery Flow Control Working Group; Boundary Layers, Transitions and Separation; Efficiency Considerations in Low Pressure Turbines; Summary of Conference; and Final Plenary Session

  12. Gravity Effects in Microgap Flow Boiling

    Science.gov (United States)

    Robinson, Franklin; Bar-Cohen, Avram

    2017-01-01

    Increasing integration density of electronic components has exacerbated the thermal management challenges facing electronic system developers. The high power, heat flux, and volumetric heat generation of emerging devices are driving the transition from remote cooling, which relies on conduction and spreading, to embedded cooling, which facilitates direct contact between the heat-generating device and coolant flow. Microgap coolers employ the forced flow of dielectric fluids undergoing phase change in a heated channel between devices. While two phase microcoolers are used routinely in ground-based systems, the lack of acceptable models and correlations for microgravity operation has limited their use for spacecraft thermal management. Previous research has revealed that gravitational acceleration plays a diminishing role as the channel diameter shrinks, but there is considerable variation among the proposed gravity-insensitive channel dimensions and minimal research on rectangular ducts. Reliable criteria for achieving gravity-insensitive flow boiling performance would enable spaceflight systems to exploit this powerful thermal management technique and reduce development time and costs through reliance on ground-based testing. In the present effort, the authors have studied the effect of evaporator orientation on flow boiling performance of HFE7100 in a 218 m tall by 13.0 mm wide microgap cooler. Similar heat transfer coefficients and critical heat flux were achieved across five evaporator orientations, indicating that the effect of gravity was negligible.

  13. Effective diffusion in laminar convective flows

    International Nuclear Information System (INIS)

    Rosenbluth, M.N.; Berk, H.L.; Doxas, I.; Horton, W.

    1987-03-01

    The effective diffusion coefficient D* of a passive component, such as test particles, dye, temperature, magnetic flux, etc., is derived for motion in periodic two-dimensional incompressible convective flow with characteristic velocity v and size d in the presence of an intrinsic local diffusivity D. Asymptotic solutions for effective diffusivity D*(P) in the large P limit, with P ∼ vd/D, is shown to be of the form D* = cDP/sup 1/2/ with c being a coefficient that is determined analytically. The constant c depends on the geometry of the convective cell and on an average of the flow speed along the separatrix. The asymptotic method of evaluation applies to both free boundary and rough boundary flow patterns and it is shown that the method can be extended to more complicated patterns such as the flows generated by rotating cylinders, as in the problem considered by Nadim, Cox, and Brenner [J. Fluid Mech., 164: 185 (1986)]. The diffusivity D* is readily calculated for small P, but the evaluation for arbitrary P requires numerical methods. Monte Carlo particle simulation codes are used to evaluate D* at arbitrary P, and thereby describe the transition for D* between the large and small P limits

  14. Internal structure and interfacial velocity development for bubbly two-phase flow

    International Nuclear Information System (INIS)

    Kocamustafaogullari, G.; Huang, W.D.

    1994-01-01

    This paper describes an experimental study of the internal structure of air-water flowing horizontally. The double-sensor resistivity probe technique was applied for measurements of local interfacial parameters, including void fraction, interfacial area concentration, bubble size distributions, bubble passing frequency and bubble interface velocity. Bubbly flow patterns at several flow conditions were examined at three axial locations, L/D=25, 148 and 253, in which the first measurement represents the entrance region where the flow develops, and the second and third may represent near fully developed bubbly flow patterns. The experimental results are presented in three-dimensional perspective plots of the interfacial parameters over the cross-section. These multi-dimensional presentations showed that the local values of the void fraction, interfacial area concentration and bubble passing frequency were nearly constant over the cross-section at L/D=25, with slight local peaking close to the channel wall. Although similar local peakings were observed at the second and third locations, the internal flow structure segregation due to buoyancy appeared to be very strong in the axial direction. A simple comparison of profiles of the interfacial parameters at the three locations indicated that the flow pattern development was a continuous process. Finally, it was shown that the so-called ''fully developed'' bubbly two-phase flow pattern cannot be established in a horizontal pipe and that there was no strong correspondence between void fraction and interface velocity profiles. ((orig.))

  15. Calculation of the separate parameters of a countercurrent centrifuge with an axially varying internal flow

    International Nuclear Information System (INIS)

    Migliavacca, S.C.P.

    1991-01-01

    A review of the isotope separation theory for the countercurrent gas centrifuge is presented. The diffusion-convection equation is solved according to the ONSAGER-COHEN solution for the constant internal flow and adapted to an axially varying countercurrent flow. Based on that theory, a numerical program is developed for the calculation of the isotopic compositions and the separative parameters of the centrifuge. The influence of the feed flow and the internal parameters. Like cut and countercurrent flow, on the separative parameters is then analysed for a model-centrifuge, which afterwards is optimized with respect to its separative power. Finally, a comparison between the present calculation procedure and some published results, provided by different theories, shows deviations lower then 20%. (author)

  16. FFTF scale-model characterization of flow-induced vibrational response of reactor internals

    International Nuclear Information System (INIS)

    Ryan, J.A.; Julyk, L.J.

    1977-01-01

    As an integral part of the Fast Test Reactor Vibration Program for Reactor Internals, the flow-induced vibrational characteristics of scaled Fast Test Reactor core internal and peripheral components were assessed under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup. The Hydraulic Core Mockup, a 0.285 geometric scale model, was designed to model the vibrational and hydraulic characteristics of the Fast Test Reactor. Model component vibrational characteristics were measured and determined over a range of 36 percent to 111 percent of the scaled prototype design flow. Selected model and prototype components were shaker tested to establish modal characteristics. The dynamic response of the Hydraulic Core Mockup components exhibited no anomalous flow-rate dependent or modal characteristics, and prototype response predictions were adjudged acceptable

  17. FFTF scale-model characterization of flow induced vibrational response of reactor internals

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, J A; Julyk, L J [Hanford Engineering Development Laboratory, Richland, WA (United States)

    1977-12-01

    As an integral part of the Fast Test Reactor Vibration Program for Reactor Internals, the flow-induced vibrational characteristics of scaled Fast Test Reactor core internal and peripheral components were assessed under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup. The Hydraulic Core Mockup, a 0.285 geometric scale model, was designed to model the vibrational and hydraulic characteristics of the Fast Test Reactor. Model component vibrational characteristics were measured and determined over a range of 36% to 111% of the scaled prototype design flow. Selected model and prototype components were shaker tested to establish modal characteristics. The dynamic response of the Hydraulic Core Mockup components exhibited no anomalous flow-rate dependent or modal characteristics, and prototype response predictions were adjudged acceptable. (author)

  18. FFTF scale-model characterization of flow induced vibrational response of reactor internals

    International Nuclear Information System (INIS)

    Ryan, J.A.; Julyk, L.J.

    1977-01-01

    As an integral part of the Fast Test Reactor Vibration Program for Reactor Internals, the flow-induced vibrational characteristics of scaled Fast Test Reactor core internal and peripheral components were assessed under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup. The Hydraulic Core Mockup, a 0.285 geometric scale model, was designed to model the vibrational and hydraulic characteristics of the Fast Test Reactor. Model component vibrational characteristics were measured and determined over a range of 36% to 111% of the scaled prototype design flow. Selected model and prototype components were shaker tested to establish modal characteristics. The dynamic response of the Hydraulic Core Mockup components exhibited no anomalous flow-rate dependent or modal characteristics, and prototype response predictions were adjudged acceptable. (author)

  19. Downstream Effects on Orbiter Leeside Flow Separation for Hypersonic Flows

    Science.gov (United States)

    Buck, Gregory M.; Pulsonetti, Maria V.; Weilmuenster, K. James

    2005-01-01

    Discrepancies between experiment and computation for shuttle leeside flow separation, which came to light in the Columbia accident investigation, are resolved. Tests were run in the Langley Research Center 20-Inch Hypersonic CF4 Tunnel with a baseline orbiter model and two extended trailing edge models. The extended trailing edges altered the wing leeside separation lines, moving the lines toward the fuselage, proving that wing trailing edge modeling does affect the orbiter leeside flow. Computations were then made with a wake grid. These calculations more closely matched baseline experiments. Thus, the present findings demonstrate that it is imperative to include the wake flow domain in CFD calculations in order to accurately predict leeside flow separation for hypersonic vehicles at high angles of attack.

  20. Calculation of external-internal flow fields for mixed-compression inlets

    Science.gov (United States)

    Chyu, W. J.; Kawamura, T.; Bencze, D. P.

    1987-01-01

    Supersonic inlet flows with mixed external-internal compressions were computed using a combined implicit-explicit (Beam-Warming-Steger/MacCormack) method for solving the three-dimensional unsteady, compressible Navier-Stokes equations in conservation form. Numerical calculations were made of various flows related to such inlet operations as the shock-wave intersections, subsonic spillage around the cowl lip, and inlet started versus unstarted conditions. Some of the computed results were compared with wind tunnel data.

  1. The value relevance of direct cash flows under international financial reporting standards

    OpenAIRE

    Clacher, I; de Ricquebourg, AD; Hodgson, A

    2013-01-01

    This study examines if there has been a change in the value relevance of direct cash flow components since the adoption of International Financial Reporting Standards (IFRS) in Australia. Our results show that for both industrial and extractive firms direct cash flow statements are value relevant under Australian Generally Accepted Accounting Principles (AGAAP) and remain so after the adoption of IFRS. In addition, for industrial firms there is a significant increase in the value relevance of...

  2. Thermal radiation effects on hydromagnetic flow

    International Nuclear Information System (INIS)

    Abdelkhalek, M.M.

    2005-01-01

    Numerical results are presented for the effects of thermal radiation, buoyancy and heat generation or absorption on hydromagnetic flow over an accelerating permeable surface. These results are obtained by solving the coupled nonlinear partial differential equations describing the conservation of mass, momentum and energy by a perturbation technique. This qualitatively agrees with the expectations, since the magnetic field exerts a retarding force on the free convection flow. A parametric study is performed to illustrate the influence of the radiation parameter, magnetic parameter, Prandtl number, Grashof number and Schmidt number on the profiles of the velocity components and temperature. The effects of the different parameters on the velocity and temperature profiles as well as the skin friction and wall heat transfer are presented graphically. Favorable comparisons with previously published work confirm the correctness of numerical results

  3. Structural effects on electromagnetic flow coupler performance

    International Nuclear Information System (INIS)

    Aoyama, Goro; Yokota, Norikatsu; Mine, Masao; Watanabe, Takashi; Takuma, Tadasu; Takenaka, Kiyoshi.

    1992-01-01

    A prototype electromagnetic flow coupler was tested using 300degC liquid sodium to estimate the effect on performance of generator flow velocity, magnetic flux density, magnetic core length and bus bar length. Its performance was not affected by changes in fluid velocity and magnetic flux density up to 8.3 m/s and 0.51 T, respectively. Besides the experiments, a two-dimensional numerical analysis program based on Ohm's law and the current continuity equation was prepared to estimate the effects of magnetic core length and bus bar construction. The current transferred from the generator to the pump, the current transfer ratio, increased by lengthening the magnetic core being a maximum of 0.706 for a 100 mm core and 0.764 for a 300 mm core. The numerical results showed that the presence of the bus bar in the outer region of the magnetic core gave inferior performance to that in its absence. (author)

  4. International portfolio flows and exchange rate volatility for emerging markets

    OpenAIRE

    Caporale, Guglielmo Maria; Ali, Faek Menla; Spagnolo, Fabio; Spagnolo, Nicola

    2015-01-01

    This paper investigates the effects of equity and bond portfolio inflows on exchange rate volatility, using monthly bilateral data for the US vis-a-vis eight Asian developing and emerging countries (India, Indonesia, South Korea, Pakistan, Hong Kong, Thailand, the Philippines, and Taiwan) over the period 1993:01-2012:11, and estimating a time-varying transition probability Markov-switching model. We find that net equity (bond) inflows drive the exchange rate to a high (low) volatility state. ...

  5. Internal flow and evaporation characteristic inside a water droplet on a vertical vibrating hydrophobic surface

    International Nuclear Information System (INIS)

    Kim Hun; Lim, Hee Chang

    2015-01-01

    This study aims to understand the internal flow and the evaporation characteristics of a deionized water droplet subjected to vertical forced vibrations. To predict and evaluate its resonance frequency, the theories of Lamb, Strani, and Sabetta have been applied. To visualize the precise mode, shape, and internal flow inside a droplet, the experiment utilizes a combination of a high-speed camera, macro lens, and continuous laser. As a result, a water droplet on a hydrophobic surface has its typical shape at each mode, and complicated vortices are observed inside the droplet. In particular, large symmetrical flow streams are generated along the vertical axis at each mode, with a large circulating movement from the bottom to the top and then to the triple contact line along the droplet surface. In addition, a bifurcation-shaped flow pattern is formed at modes 2 and 4, whereas a large ellipsoid-shape flow pattern forms at modes 6 and 8. Mode 4 has the fastest internal flow speed and evaporation rate, followed by modes 8 then 6, with 2 having the slowest of these properties. Each mode has the fastest evaporation rate amongst its neighboring frequencies. Finally, the droplet evaporation under vertical vibration would lead to more rapid evaporation, particularly for mode 4

  6. Internal flow and evaporation characteristic inside a water droplet on a vertical vibrating hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Kim Hun; Lim, Hee Chang [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

    2015-07-15

    This study aims to understand the internal flow and the evaporation characteristics of a deionized water droplet subjected to vertical forced vibrations. To predict and evaluate its resonance frequency, the theories of Lamb, Strani, and Sabetta have been applied. To visualize the precise mode, shape, and internal flow inside a droplet, the experiment utilizes a combination of a high-speed camera, macro lens, and continuous laser. As a result, a water droplet on a hydrophobic surface has its typical shape at each mode, and complicated vortices are observed inside the droplet. In particular, large symmetrical flow streams are generated along the vertical axis at each mode, with a large circulating movement from the bottom to the top and then to the triple contact line along the droplet surface. In addition, a bifurcation-shaped flow pattern is formed at modes 2 and 4, whereas a large ellipsoid-shape flow pattern forms at modes 6 and 8. Mode 4 has the fastest internal flow speed and evaporation rate, followed by modes 8 then 6, with 2 having the slowest of these properties. Each mode has the fastest evaporation rate amongst its neighboring frequencies. Finally, the droplet evaporation under vertical vibration would lead to more rapid evaporation, particularly for mode 4.

  7. Stratified flows and internal waves in the Vema Fracture Zone of the Mid Atlantic Ridge

    Science.gov (United States)

    Makarenko, Nikolay; Morozov, Eugene; Tarakanov, Roman; Demidova, Tatiana; Frey, Dmitri; Grigorenko, Klim

    2017-04-01

    In this paper, we study stratified flows and internal waves in the Vema fracture zone of the Mid Atlantic Ridge. This fracture provides intense transportation of cold abyssal waters from the West Atlantic to the equatorial region of the East Atlantic [1]. The results of measurements [2,3] carried out in the cruises of RV Akademik Sergey Vavilov in 2014-2016 are presented. The structure of the near-bottom flow is studied experimentally on the basis of CTD- and LADCP profiling. Theoretical analysis involves mathematical formulation of stratified fluid flow which uses CTD-data obtained from field observation. Spectral properties and kinematic characteristics of internal waves are calculated and discussed. This work was supported by RFBR (grants No 15-01-03942, 16-35-50158). References [1] Morozov E., Demidov A., Tarakanov R. and Zenk W. Abyssal Channels in the Atlantic Ocean: Water Structure and Flows, Springer, Dordrecht, 2010. [2] Morozov E.G., Tarakanov R.Yu., and Makarenko N.I. Flows of Antarctic Bottom Water through fractures in the southern part of the North Mid Atlantic Ridge, Oceanology, 2015, 55, 796-800. [3] Grigorenko K.S., Makarenko N.I., Morozov E.G., Tarakanov R.Yu., and Frey D.I. Stratified flows and internal waves in the Central West Atlantic, J. Physics: Conf. Series, 2016, 722, 012011.

  8. Ideal Internal Carotid Artery Trapping Technique without Bypass in a Patient with Insufficient Collateral Flow.

    Science.gov (United States)

    Chung, Joon Ho; Shin, Yong Sam; Lim, Yong Cheol; Park, Minjung

    2009-04-01

    Internal carotid artery (ICA) trapping can be used for treating intracranial giant aneurysm, blood blister-like aneurysms and ICA rupture during the surgery. We present a novel ICA trapping technique which can be used with insufficient collaterals flow via anterior communicating artery (AcoA) and posterior communicating artery (PcoA). A patient was admitted with severe headache and the cerebral angiography demonstrated a typical blood blister-like aneurysm at the contralateral side of PcoA. For trapping the aneurysm, the first clip was placed at the ICA just proximal to the aneurysm whereas the distal clip was placed obliquely proximal to the origin of the PcoA to preserve blood flow from the PcoA to the distal ICA. The patient was completely recovered with good collaterals filling to the right ICA territories via AcoA and PcoA. This technique may be an effective treatment option for trapping the aneurysm, especially when the PcoA preservation is mandatory.

  9. Method for calculating internal radiation and ventilation with the ADINAT heat-flow code

    International Nuclear Information System (INIS)

    Butkovich, T.R.; Montan, D.N.

    1980-01-01

    One objective of the spent fuel test in Climax Stock granite (SFTC) is to correctly model the thermal transport, and the changes in the stress field and accompanying displacements from the application of the thermal loads. We have chosen the ADINA and ADINAT finite element codes to do these calculations. ADINAT is a heat transfer code compatible to the ADINA displacement and stress analysis code. The heat flow problem encountered at SFTC requires a code with conduction, radiation, and ventilation capabilities, which the present version of ADINAT does not have. We have devised a method for calculating internal radiation and ventilation with the ADINAT code. This method effectively reproduces the results from the TRUMP multi-dimensional finite difference code, which correctly models radiative heat transport between drift surfaces, conductive and convective thermal transport to and through air in the drifts, and mass flow of air in the drifts. The temperature histories for each node in the finite element mesh calculated with ADINAT using this method can be used directly in the ADINA thermal-mechanical calculation

  10. International capital flows and investment volatility in selected sub-Saharan African countries

    Directory of Open Access Journals (Sweden)

    William Brafu-Insaidoo

    2011-07-01

    Full Text Available The study examines the impact of foreign capital flows on investment volatility in emerging and frontier market economies in sub-Saharan Africa. In particular, the study attempts to answer the question of whether different components of foreign capital inflows explain investment volatility. Theory suggests that increased cross-border capital mobility increases investment volatility due to the possibility of substituting foreign for domestic investments. Empirical literature does not, however, provide any clear evidence in support of this theory. By using the dynamic panel data analysis, this study tests the hypothesis that increased capital flows increases investment volatility and the study established that international capital flows reduce investment volatility.

  11. Self-organizing hybrid Cartesian grid generation and application to external and internal flow problems

    Energy Technology Data Exchange (ETDEWEB)

    Deister, F.; Hirschel, E.H. [Univ. Stuttgart, IAG, Stuttgart (Germany); Waymel, F.; Monnoyer, F. [Univ. de Valenciennes, LME, Valenciennes (France)

    2003-07-01

    An automatic adaptive hybrid Cartesian grid generation and simulation system is presented together with applications. The primary computational grid is an octree Cartesian grid. A quasi-prismatic grid may be added for resolving the boundary layer region of viscous flow around the solid body. For external flow simulations the flow solver TAU from the ''deutsche zentrum fuer luft- und raumfahrt (DLR)'' is integrated in the simulation system. Coarse grids are generated automatically, which are required by the multilevel method. As an application to an internal problem the thermal and dynamic modeling of a subway station is presented. (orig.)

  12. Lattice Boltzmann equation calculation of internal, pressure-driven turbulent flow

    International Nuclear Information System (INIS)

    Hammond, L A; Halliday, I; Care, C M; Stevens, A

    2002-01-01

    We describe a mixing-length extension of the lattice Boltzmann approach to the simulation of an incompressible liquid in turbulent flow. The method uses a simple, adaptable, closure algorithm to bound the lattice Boltzmann fluid incorporating a law-of-the-wall. The test application, of an internal, pressure-driven and smooth duct flow, recovers correct velocity profiles for Reynolds number to 1.25 x 10 5 . In addition, the Reynolds number dependence of the friction factor in the smooth-wall branch of the Moody chart is correctly recovered. The method promises a straightforward extension to other curves of the Moody chart and to cylindrical pipe flow

  13. Canadian and international approaches to regulatory effectiveness

    International Nuclear Information System (INIS)

    Lojk, R.

    2014-01-01

    Regulatory effectiveness is an important attribute of any regulator, particularly nuclear regulators. As the nuclear industry has matured, and as the social landscape has changed, so have views on what constitutes regulatory effectiveness. Canada has evolved its regulatory structure and modernized its legislative framework and technical requirements and guidance over time. In addition, Canada continues to collaborate with international agencies, particularly the NEA and the IAEA, to ensure that there is a common understanding of the indicators and key attributes of regulatory effectiveness. This paper discusses Canadian and international views on the subject, including perspectives from other industries. (author)

  14. Investigations of internal turbulent flows in a low-head tubular pump and its performance predictions

    International Nuclear Information System (INIS)

    Tang, X L; Chen, X S; Wang, F J; Yang, W; Wu, Y L

    2012-01-01

    Based on the RANS equations, standard k−ε turbulence model and SIMPLE algorithm, the internal turbulent flows in a low-head tubular pump were simulated by using the FLUENT software. Based on the predicted flow fields, the external performance curves including the head-discharge, efficiency-discharge and power-discharge curves were further obtained. The calculated results indicate that the internal flow pattern is smooth at the best efficiency point (BEP). When it works under off-design operating cases, the flow pattern inside the diffuser and the discharge passage is disorder, and at the same time, the hydraulic losses mainly come from the secondary flows. At large flow rates, the minimum static pressure near the inlet of the blade pressure surfaces due to the negative attack angle. At small flow rates, the minimum value happens near the inlet of the suction surfaces. At the BEP, the lowest static pressure appears in the region behind the suction surfaces inlet. The newly-designed model is validated by the comparisons between its predicted external performance and the experimental data of the JGM-3 model. This research provides some important references for the optimization of a low-head tubular pump.

  15. Strain gradient crystal plasticity effects on flow localization

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    for metals described by the reformulated Fleck-Hutchinson strain gradient plasticity theory. The theory is implemented numerically within a finite element framework using slip rate increments and displacement increments as state variables. The formulation reduces to the classical crystal plasticity theory...... in the absence of strain gradients. The model is used to study the effect of an internal material length scale on the localization of plastic flow in shear bands in a single crystal under plane strain tension. It is shown that the mesh sensitivity is removed when using the nonlocal material model considered...

  16. Drag with external and pressure drop with internal flows: a new and unifying look at losses in the flow field based on the second law of thermodynamics

    International Nuclear Information System (INIS)

    Herwig, Heinz; Schmandt, Bastian

    2013-01-01

    Internal and external flows are characterized by friction factors and drag coefficients, respectively. Their definitions are based on pressure drop and drag force and thus are very different in character. From a thermodynamics point of view in both cases dissipation occurs which can uniformly be related to the entropy generation in the flow field. Therefore we suggest to account for losses in the flow field by friction factors and drag coefficients that are based on the overall entropy generation due to the dissipation in the internal and external flow fields. This second law analysis (SLA) has been applied to internal flows in many studies already. Examples of this flow category are given together with new cases of external flows, also treated by the general SLA-approach. (paper)

  17. Flow regime effects on non-cavitating injection nozzles over spray behavior

    Energy Technology Data Exchange (ETDEWEB)

    Payri, R., E-mail: rpayri@mot.upv.e [CMT-Motores Termicos, Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia E-46022 (Spain); Salvador, F.J.; Gimeno, J.; Novella, R. [CMT-Motores Termicos, Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia E-46022 (Spain)

    2011-02-15

    This paper deals with the influence of flow regime (laminar, transition or turbulent) on the internal flow behavior, and how it affects the spray development in diesel nozzles. In particular, the research described here aims at studying and quantifying the internal flow regime effects on the spray behavior. With this purpose, internal flow results, based on mass flow rate and momentum flux measurements performed on three different tapered nozzles and which helped to determine the flow regime, has been taken into account as a point of departure for the spray behavior analysis. Thus, in this work, spray macroscopic visualization tests have been performed and analyzed which clearly revealed a change in the behavior of the angle and penetration of the spray related to the change of the flow nature. Moreover, with all the experimental data available, it has been possible to relate macroscopic parameters of the spray with those describing the internal flow (momentum and effective velocity) or the geometry of the nozzle (length or diameter) through correlations.

  18. Controlling the Internal Heat Transfer Coefficient by the Characteristics of External Flows

    Science.gov (United States)

    Zhuromskii, V. M.

    2018-01-01

    The engineering-physical fundamentals of substance synthesis in a boiling apparatus are presented. We have modeled a system of automatic stabilization of the maximum internal heat transfer coefficient in such an apparatus by the characteristics of external flows on the basis of adaptive seeking algorithms. The results of operation of the system in the shop are presented.

  19. Towards a universal scaling for broadband turbulent noise in internal flow devices

    NARCIS (Netherlands)

    Jong, A.T. de; Golliard, J.

    2013-01-01

    An investigation is performed on the scalability of broadband noise sources from separated flows in internal pipe systems. Broadband sources from for example wellhead chokes, bends and valves can potentially excite subsea manifolds through fluid acoustic coupling and fluid structural coupling. The

  20. Finite element simulation of internal flows with heat transfer using a ...

    Indian Academy of Sciences (India)

    Unknown

    Velocity correction method; finite element simulation; turbulent .... CFD, developments in turbulence modeling have been only evolutionary and ...... variables are made dimensionless using appropriate combinations of Uav, H, ...... Srinivas M 1994 Finite element analysis of internal flows with heat transfer Ph D thesis, Indian.

  1. Capital flows, bazookas and unconventional monetary policy : Essays in international financial stability

    NARCIS (Netherlands)

    Frost, Jonathon Jeffrey

    2015-01-01

    Do international capital flows make countries more or less vulnerable to financial crises? Should countries shield their economies from stress with capital controls? ‎Once a crisis hits, should the public sector launch large-scale support programs ("bazookas")? And if the central bank decides to

  2. A distributed control algorithm for internal flow management in a multi-zone climate unit

    NARCIS (Netherlands)

    Persis, C. De; Jessen, J.J.; Izadi-Zamanabadi, R.; Schiøler, H.

    2008-01-01

    We examine a distributed control problem for internal flow management in a multi-zone climate unit. The problem consists of guaranteeing prescribed indoor climate conditions in a cascade connection of an arbitrarily large number of communicating zones, in which air masses are exchanged to redirect

  3. "The Free Flow of News" and "Western Communication Imperialism": Divergent Views on Ethics in International Communication.

    Science.gov (United States)

    Merrill, John C.

    A growing international controversy exists between the West on one hand and the Third World, Marxist states, and the United Nations Educational, Scientific, and Cultural Organization (UNESCO) on the other focusing on the concepts of "free flow of information" and "Western communication imperialism," and on ethical issues relating to these…

  4. Combined effect of external and internal irradiation

    International Nuclear Information System (INIS)

    Kiradzhiev, G.

    1987-01-01

    Some of the general regularities of the combined effect of external irradiation and iodine 131 are discussed. Data are adduced showing that modification of the effects of these two radiation factors, when jointly applied, is also determined by the quantitative relations of the applied doses of external and internal irradiation, referred to a particular moment of the effects. It was shown that the effects of the radionuclides in these combined radiation injuries are basically realized by two mechanisms: 1. changes are found in the radionuclide kinetic parameters (nonspecific effects); 2. changes in their kinetic parameters are absent (specific effect). These two mechanisms underlie different approaches to therapy

  5. Heat transfer of liquid-metal magnetohydrodynamic flow with internal heat generation

    International Nuclear Information System (INIS)

    Kumamaru, Hiroshige; Kurita, Kazuhisa; Kodama, Satoshi

    2000-01-01

    Numerical calculations on heat transfer of a magnetohydrodynamic (MHD) flow with internal heat generation in a rectangular channel have been performed for the cases of very-large Hartmann numbers, finite wall conductivities and small aspect ratio (i.e. small length ratios of the channel side perpendicular to the applied magnetic field and the side parallel to the field), simulating typical conditions for a fusion-reactor blanket. The Nusselt numbers of the MHD flow in rectangular channels with aspect ratios of 1/10 to 1/40 for Hartmann numbers of ∼5 x 10 5 become ∼10 times higher than those for the corresponding flow under no magnetic field. The Nusselt number becomes higher as the internal heat generation rate increases as far as the heat generation rates in a fusion reactor blanket are considered. (author)

  6. Gas-kinetic unified algorithm for hypersonic flows covering various flow regimes solving Boltzmann model equation in nonequilibrium effect

    International Nuclear Information System (INIS)

    Li, Zhihui; Ma, Qiang; Wu, Junlin; Jiang, Xinyu; Zhang, Hanxin

    2014-01-01

    Based on the Gas-Kinetic Unified Algorithm (GKUA) directly solving the Boltzmann model equation, the effect of rotational non-equilibrium is investigated recurring to the kinetic Rykov model with relaxation property of rotational degrees of freedom. The spin movement of diatomic molecule is described by moment of inertia, and the conservation of total angle momentum is taken as a new Boltzmann collision invariant. The molecular velocity distribution function is integrated by the weight factor on the internal energy, and the closed system of two kinetic controlling equations is obtained with inelastic and elastic collisions. The optimization selection technique of discrete velocity ordinate points and numerical quadrature rules for macroscopic flow variables with dynamic updating evolvement are developed to simulate hypersonic flows, and the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions. The gas-kinetic boundary conditions in thermodynamic non-equilibrium and numerical procedures are studied and implemented by directly acting on the velocity distribution function, and then the unified algorithm of Boltzmann model equation involving non-equilibrium effect is presented for the whole range of flow regimes. The hypersonic flows involving non-equilibrium effect are numerically simulated including the inner flows of shock wave structures in nitrogen with different Mach numbers of 1.5-Ma-25, the planar ramp flow with the whole range of Knudsen numbers of 0.0009-Kn-10 and the three-dimensional re-entering flows around tine double-cone body

  7. Blood flows in the maxillocarotid anastomoses and internal carotid artery of conscious dogs.

    Science.gov (United States)

    Lee, M C; Reid, I A; Ramsay, D J

    1986-06-01

    Although the external carotid artery is known to contribute to the cerebral blood flow in anesthetized dogs, quantitative information on the anastomoses and their role in conscious dogs is lacking. This study was carried out to determine blood flows in these anastomoses and the internal carotid artery, and also to examine the functional significance of the anastomoses in conscious dogs. Fifteen-micron radioactive microspheres were injected into common and external carotid arteries of four conscious dogs through chronically implanted catheters. Blood flows were determined by the reference sample method and by comparing microsphere distributions in the brain and the masseter muscle. Blood flows were estimated to be 140 +/- 32, 7.7 +/- 1.4, and 3.3 +/- 1.1 ml/minute (mean +/- SD) in the common carotid artery, internal carotid artery, and anastomoses on each side, respectively. Additional evidence indicated that the anastomotic flow so determined was primarily the flow in the anastomotic artery. Humoral responses to angiotensin II infusions were also studied in conscious dogs. External carotid angiotensin increased plasma 11-hydroxycorticosteroid concentration (used as an index of ACTH secretion) but did not increase plasma vasopressin concentration to the same extent as common carotid infusion. Therefore, the external carotid artery is functionally important in perfusing the brain in conscious dogs.

  8. Surface Effects on Nanoscale Gas Flows

    Science.gov (United States)

    Beskok, Ali; Barisik, Murat

    2010-11-01

    3D MD simulations of linear Couette flow of argon gas confined within nano-scale channels are performed in the slip, transition and free molecular flow regimes. The velocity and density profiles show deviations from the kinetic theory based predictions in the near wall region that typically extends three molecular diameters (s) from each surface. Utilizing the Irwin-Kirkwood theorem, stress tensor components for argon gas confined in nano-channels are investigated. Outside the 3s region, three normal stress components are identical, and equal to pressure predicted using the ideal gas law, while the shear stress is a constant. Within the 3s region, the normal stresses become anisotropic and the shear stress shows deviations from its bulk value due to the surface virial effects. Utilizing the kinetic theory and MD predicted shear stress values, the tangential momentum accommodation coefficient for argon gas interacting with FCC structured walls (100) plane facing the fluid is calculated to be 0.75; this value is independent of the Knudsen number. Results show emergence of the 3s region as an additional characteristic length scale in nano-confined gas flows.

  9. International workshop on measuring techniques for liquid metal flows (MTLM). Abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Gerbeth, G; Eckert, S [eds.

    1999-11-01

    The international workshop on 'Measuring techniques in liquid metal flows' (MTLM workshop) was organised in frame of the Dresden 'Innovationskolleg Magnetofluiddynamik'. The subject of the MTLM workshop was limited to methods to determine physical flow quantities such as velocity, pressure, void fraction, inclusion properties, crystallisation fronts etc. The present proceedings contain abstracts and viewgraphs of the oral presentations. During the last decades numerical simulations have become an important tool in industry and research to study the structure of flows and the properties of heat and mass transfer. However, in case of liquid metal flows there exists a significant problem to validate the codes with experimental data due to the lack of available measuring techniques. Due to the material properties (opaque, hot, chemical aggressive) the measurement of flow quantities is much more delicate in liquid metals compared to ordinary water flows. The generalisation of results obtained by means of water models to real liquid metal flows has often to be considered as difficult due to the problems to meet the actual values of n0n-dimensional flow parameters (Re, Pr, Gr, Ha, etc.). Moreover, a strong need has to be noted to make measuring techniques available tomonitor and to control flow processes in real industrial facilities. The objectives of the MTLM workshop were to: Review of existing information on a available techniques and experiences about the use in liquid metal flows, initiate a discussion between developers and potential users with respect to the actual need of information about the flow structure as well as the capabilities of existing and developing measuring techniques. Explore opportunities for co-operative R and D projects to expedite new developments and results, to share expertise and resources. (orig.)

  10. International workshop on measuring techniques for liquid metal flows (MTLM). Abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Gerbeth, G.; Eckert, S. [eds.

    1999-11-01

    The international workshop on 'Measuring techniques in liquid metal flows' (MTLM workshop) was organised in frame of the Dresden 'Innovationskolleg Magnetofluiddynamik'. The subject of the MTLM workshop was limited to methods to determine physical flow quantities such as velocity, pressure, void fraction, inclusion properties, crystallisation fronts etc. The present proceedings contain abstracts and viewgraphs of the oral presentations. During the last decades numerical simulations have become an important tool in industry and research to study the structure of flows and the properties of heat and mass transfer. However, in case of liquid metal flows there exists a significant problem to validate the codes with experimental data due to the lack of available measuring techniques. Due to the material properties (opaque, hot, chemical aggressive) the measurement of flow quantities is much more delicate in liquid metals compared to ordinary water flows. The generalisation of results obtained by means of water models to real liquid metal flows has often to be considered as difficult due to the problems to meet the actual values of n0n-dimensional flow parameters (Re, Pr, Gr, Ha, etc.). Moreover, a strong need has to be noted to make measuring techniques available tomonitor and to control flow processes in real industrial facilities. The objectives of the MTLM workshop were to: Review of existing information on a available techniques and experiences about the use in liquid metal flows, initiate a discussion between developers and potential users with respect to the actual need of information about the flow structure as well as the capabilities of existing and developing measuring techniques. Explore opportunities for co-operative R and D projects to expedite new developments and results, to share expertise and resources. (orig.)

  11. Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

    Science.gov (United States)

    Whitesides, R. H.; Ghosh, A.; Jenkins, S. L.; Bacchus, D. L.

    1989-01-01

    A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru

  12. Effect of surface wettability on flow patterns in vertical gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Nakamura, D.

    2005-01-01

    To examine the effect of the surface characteristics on the flow regime in two-phase flow, visualization study was performed using three test pipes, namely a no-coating pipe, a water-attracting coating pipe, a water-shedding coating pipe. Three flow regime maps were obtained based on the visual observation in the three pipes. In the water-attracting coating pipe, the slug flow-to-churn flow transition boundary was shifted to higher gas velocity at a given liquid velocity, whereas the churn flow-to-annular flow transition boundary was shifted to lower gas velocity at a given liquid velocity. In the water shedding coating pipe, the inverted-churn flow regime was observed in the region where the churn flow regime was to be observed in a no-coating pipe, whereas the droplet flow regime was observed in the region where the annular flow regime was to be observed in a no-coating pipe. The criteria for the slug flow-to-inverted-churn flow transition and the inverted-churn flow-to-droplet flow transition were modeled by force balance approaches. The modeled transition criteria could predict the observed flow transition boundaries reasonably well. (authors)

  13. Evolution and transition mechanisms of internal swirling flows with tangential entry

    Science.gov (United States)

    Wang, Yanxing; Wang, Xingjian; Yang, Vigor

    2018-01-01

    The characteristics and transition mechanisms of different states of swirling flow in a cylindrical chamber have been numerically investigated using the Galerkin finite element method. The effects of the Reynolds number and swirl level were examined, and a unified theory connecting different flow states was established. The development of each flow state is considered as a result of the interaction and competition between basic mechanisms: (1) the centrifugal effect, which drives an axisymmetric central recirculation zone (CRZ); (2) flow instabilities, which develop at the free shear layer and the central solid-body rotating flow; (3) the bouncing and restoring effects of the injected flow, which facilitate the convergence of flow on the centerline and the formation of bubble-type vortex breakdown; and (4) the damping effect of the end-induced flow, which suppresses the development of the instability waves. The results show that the CRZ, together with the free shear layer on its surface, composes the basic structure of swirling flow. The development of instability waves produces a number of discrete vortex cores enclosing the CRZ. The azimuthal wave number is primarily determined by the injection angle. Generally, the wave number is smaller at a higher injection angle, due to the reduction of the perimeter of the free shear layer. At the same time, the increase in the Reynolds number facilitates the growth of the wave number. The end-induced flow tends to reduce the wave number near the head end and causes a change in wave number from the head end to the downstream region. Spiral-type vortex breakdown can be considered as a limiting case at a high injection angle, with a wave number equal to 0 near the head end and equal to 1 downstream. At lower Reynolds numbers, the bouncing and restoring effect of the injected flow generates bubble-type vortex breakdown.

  14. Genetic effects from internally deposited radionuclides

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    It was learned in the late 1920's that ionizing radiation could produce genetic effects such as gene mutations and chromosome aberrations. However, at least until 1945, the focus on interest in radiation protection was primarily on somatic effects manifested in the individual exposed. Studies of the genetic effects of radiation using drosophila, however, refocused attention on effects transmitted to the exposed individuals offspring and concern over fallout in the 1950's resulted in efforts to estimate the genetic effects from exposure of human populations to internally deposited radionuclides. No human populations have been identified with burdens of internally deposited radioactive materials which have been shown to produce evidence of transmissible genetic damage. As a result, the research approach has been one in which macromolecular, cellular, and whole animal genetic studies have been combined to estimate genetic effects on humans following the deposition of radioactive materials in the body. The purpose of this report is to update the information available from animal and cellular experiments that relates genetic effects to deposited activity and dose from internally deposited radioactive materials

  15. Collateral Flow and White Matter Disease in Patients with Internal Carotid Artery Occlusion.

    Science.gov (United States)

    Ishikawa, Mami; Sugawara, Hitoshi; Nagai, Mutsumi; Kusaka, Gen; Tanaka, Yuichi; Naritaka, Heiji

    2017-01-01

    When an internal carotid artery (ICA) occludes, a patient may develop cerebral infarction (CI). We investigated whether CI caused by ICA occlusion (ICAO) is associated with collateral flow through the anterior and posterior communicating arteries (ACoA and PCoA). In 100 patients with ICAO, we investigated CI and white matter disease by performing an MRI and the anatomy of the ACoA and PCoA were investigated by performing magnetic resonance angiography. All patients were divided into the symptomatic CI group or the no-CI group. The collateral flow pathway was estimated by the anterior cerebral artery (ACA)-PCoA score and the collateral flow volume after ICAO was estimated by the middle cerebral artery (MCA) flow score, based on how well the MCA was visualized. Of 100 patients with ICAO, the symptomatic CI group included 36 patients. ACA-PCoA score and white matter disease grades were significantly higher in the CI group (indicating poor collateral flow). More than 80% of patients with an ACA-PCoA score of 4 (poor collateral) experienced symptomatic CI. Thirty-one symptomatic CI patients (86%) had an MCA flow score of 1 or 2 (decreased MCA flow). The ACA-PCoA score and white matter disease grade may suggest an increased risk of CI following ICAO. © 2016 S. Karger AG, Basel.

  16. Dopexamine increases internal mammary artery blood flow following coronary artery bypass grafting.

    LENUS (Irish Health Repository)

    Flynn, Michael J

    2012-02-03

    OBJECTIVE: Vasoactive agents and inotropes influence conduit-coronary blood flow following coronary artery bypass grafting (CABG). It was hypothesized that dopexamine hydrochloride, a dopamine A-1 (DA-1) and beta(2) agonist would increase conduit-coronary blood flow. A prospective randomized double blind clinical trial was carried out to test this hypothesis. DA-1 receptors have previously been localized to human left ventricle. METHODS: Twenty-six American Society of Anaesthesiology class 2-3 elective coronary artery bypass graft patients who did not require inotropic support on separation from cardiopulmonary bypass (CPB) were studied. According to a randomized allocation patients received either dopexamine (1 microg\\/kg per min) or placebo (saline) by intravenous infusion for 15 min. Immediately prior to and at 5,10 and 15 min of infusion, blood flow through the internal mammary and vein grafts (Transit time flow probes, Transonic Ltd.), heart rate, cardiac index, mean arterial pressure and pulmonary haemodynamics were noted. The data were analysed using multivariate analysis of variance. RESULTS: Low-dose dopexamine (1 microg\\/kg per min) caused a significant increase in mammary graft blood flow compared to placebo at 15 min of infusion (P=0.028, dopexamine group left internal mammary artery (LIMA) flow of 43.3+\\/-14.2 ml\\/min, placebo group LIMA flow at 26.1+\\/-16.3 ml\\/min). Dopexamine recipients demonstrated a non-significant trend to increased saphenous vein graft flow (P=0.059). Increased heart rate was the only haemodynamic change induced by dopexamine (P=0.004, dopexamine group at 85.2+\\/-9.6 beats\\/min and placebo group at 71.1+\\/-7.6 beats\\/min after 15 min of infusion). CONCLUSION: This study demonstrates that administration of dopexamine (1 microg\\/kg per min) was associated with a significant increase in internal mammary artery graft blood flow with mild increase in heart rate being the only haemodynamic change. Low-dose dopexamine may

  17. Effect of Flow Rate Controller on Liquid Steel Flow in Continuous Casting Mold using Numerical Modeling

    Science.gov (United States)

    Gursoy, Kadir Ali; Yavuz, Mehmet Metin

    2014-11-01

    In continuous casting operation of steel, the flow through tundish to the mold can be controlled by different flow rate control systems including stopper rod and slide-gate. Ladle changes in continuous casting machines result in liquid steel level changes in tundishes. During this transient event of production, the flow rate controller opening is increased to reduce the pressure drop across the opening which helps to keep the mass flow rate at the desired level for the reduced liquid steel level in tundish. In the present study, computational fluid dynamic (CFD) models are developed to investigate the effect of flow rate controller on mold flow structure, and particularly to understand the effect of flow controller opening on meniscus flow. First, a detailed validation of the CFD models is conducted using available experimental data and the performances of different turbulence models are compared. Then, the constant throughput casting operations for different flow rate controller openings are simulated to quantify the opening effect on meniscus region. The results indicate that the meniscus velocities are significantly affected by the flow rate controller and its opening level. The steady state operations, specified as constant throughput casting, do not provide the same mold flow if the controller opening is altered. Thus, for quality and castability purposes, adjusting the flow controller opening to obtain the fixed mold flow structure is proposed. Supported by Middle East Technical University (METU) BAP (Scientific Research Projects) Coordination.

  18. Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by

  19. Effect of induced cross flow on flow pattern and performance of proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Jiao, Kui; Bachman, John; Zhou, Yibo; Park, Jae Wan

    2014-01-01

    Highlights: • 3D numerical works to study the effect of cross flow on the PEMFC performance. • The cross flow ensure more evenly distributed water and oxygen in the CL. • The optimal net power output can be identified by controlling the back pressure. • Results confirm that present design is effective in improving performance. - Abstract: The cross flow in proton exchange membrane fuel cells (PEMFCs) plays an important role in changing the transport pattern and performance. In this study, three-dimensional numerical simulations are carried out to investigate the effect of induced cross flow on the flow pattern and performance of a PEMFC with a previously proposed and experimentally studied novel parallel flow channel design. The numerical results indicate that the liquid water and oxygen become more evenly distributed in the catalyst layer (CL) as the pressure difference between the low-pressure and high-pressure flow channels increases. It has been found that, in the low-pressure channels, the cross flow drives a convective flow from the CL to the flow channel resulting in improved liquid water removal. The optimal net power output can be identified by controlling the back pressure on the high-pressure flow channels. The numerical results confirm that this novel parallel flow channel design is effective in improving PEMFC performance

  20. An effect of downcomer feedwater fraction on steam generator performance with an axial flow economizer

    International Nuclear Information System (INIS)

    Jung, Byung Ryul; Park, Hu Shin; Chung, Duk Muk; Baik, Se Jin

    2000-01-01

    The effects of feedwater flow fraction introduced into the downcomer region have been evaluated in terms of steam generator performance based on the same steam generator thermal output for the Korea Standard Nuclear Power Plant (KSNP) steam generator. The KSNP steam generator design has an integral axial flow economizer which is designed such that most of the feedwater is introduced through the economizer region and only a portion of feedwater through the downcomer region. The feedwater flow introduced into the downcomer region is not normally controlled during the power operation. However, the actual feedwater fraction into the downcomer region may differ from the design flow depending on the as-built system and component characteristics. Investigated in this paper were the downcomer feedwater flow effects on the steam pressure, circulation ratio, internal void fraction and velocity distribution in the tube bundle region at the steady state operation using SAFE and ATHOS3 codes. The results show that the steam pressure increases and the resultant total feedwater flow increases with reducing the downcomer feedwater flow fraction for the same steam generator thermal output. The slight off-design condition of downcomer feedwater flow fraction renders no significant effect on the steam generator performance such as circulation ratios, steam qualities, void fractions and internal velocity distributions. The evaluation shows that the slight off-design downcomer feedwater flow fraction deviation up to ± 5% is acceptable for the steam generator performance

  1. The influence of tip clearance on performance and internal flow condition of fluid food pump using low viscous fluid

    International Nuclear Information System (INIS)

    Kubo, S; Ishioka, T; Fukutomi, J; Shigemitsu, T

    2012-01-01

    Fluid machines for fluid food have been used in wide variety of fields i.e. transportation, the filling, and for the improvement of quality of fluid foods. However, flow conditions of it are quite complicated because fluid foods are different from water. Therefore, design methods based on internal flow conditions have not been conducted. In this research, turbo-pumps having a small number of blades were used to decrease shear loss and keep wide flow passage. The influence of the tip clearance was investigated by the numerical analysis using the model with and without the tip clearance. In this paper, the influence of tip clearance on performances and internal flow conditions of turbo-pump using low viscous fluid were clarified by experimental and numerical analysis results. In addition, design methods based on the internal flow were considered. Further, the influences of viscosity on the performance characteristic and internal flow were investigated.

  2. On effects of topography in rotating flows

    Science.gov (United States)

    Burmann, Fabian; Noir, Jerome; Jackson, Andrew

    2017-11-01

    Both, seismological studies and geodynamic arguments suggest that there is significant topography at the core mantle boundary (CMB). This leads to the question whether the topography of the CMB could influence the flow in the Earth's outer core. As a preliminary experiment, we investigate the effects of bottom topography in the so-called Spin-Up, where motion of a contained fluid is created by a sudden increase of rotation rate. Experiments are performed in a cylindrical container mounted on a rotating table and quantitative results are obtained with particle image velocimetry. Several horizontal length scales of topography (λ) are investigated, ranging from cases where λ is much smaller then the lateral extend of the experiment (R) to cases where λ is a fraction of R. We find that there is an optimal λ that creates maximum dissipation of kinetic energy. Depending on the length scale of the topography, kinetic energy is either dissipated in the boundary layer or in the bulk of the fluid. Two different phases of fluid motion are present: a starting flow in the from of solid rotation (phase I), which is later replaced by meso scale vortices on the length scale of bottom topography (phase II).

  3. FEMO, A FLOW AND ENRICHMENT MONITOR FOR VERIFYING COMPLIANCE WITH INTERNATIONAL SAFEGUARDS REQUIREMENTS AT A GAS CENTRIFUGE ENRICHMENT FACILITY

    International Nuclear Information System (INIS)

    Gunning, John E.; Laughter, Mark D.; March-Leuba, Jose A.

    2008-01-01

    A number of countries have received construction licenses or are contemplating the construction of large-capacity gas centrifuge enrichment plants (GCEPs). The capability to independently verify nuclear material flows is a key component of international safeguards approaches, and the IAEA does not currently have an approved method to continuously monitor the mass flow of 235U in uranium hexafluoride (UF6) gas streams. Oak Ridge National Laboratory is investigating the development of a flow and enrichment monitor, or FEMO, based on an existing blend-down monitoring system (BDMS). The BDMS was designed to continuously monitor both 235U mass flow and enrichment of UF6 streams at the low pressures similar to those which exists at GCEPs. BDMSs have been installed at three sites-the first unit has operated successfully in an unattended environment for approximately 10 years. To be acceptable to GCEP operators, it is essential that the instrument be installed and maintained without interrupting operations. A means to continuously verify flow as is proposed by FEMO will likely be needed to monitor safeguards at large-capacity plants. This will enable the safeguards effectiveness that currently exists at smaller plants to be maintained at the larger facilities and also has the potential to reduce labor costs associated with inspections at current and future plants. This paper describes the FEMO design requirements, operating capabilities, and development work required before field demonstration.

  4. Development of Flow Boiling and Condensation Experiment on the International Space Station- Normal and Low Gravity Flow Boiling Experiment Development and Test Results

    Science.gov (United States)

    Nahra, Henry K.; Hall, Nancy R.; Hasan, Mohammad M.; Wagner, James D.; May, Rochelle L.; Mackey, Jeffrey R.; Kolacz, John S.; Butcher, Robert L.; Frankenfield, Bruce J.; Mudawar, Issam; hide

    2013-01-01

    Flow boiling and condensation have been identified as two key mechanisms for heat transport that are vital for achieving weight and volume reduction as well as performance enhancement in future space systems. Since inertia driven flows are demanding on power usage, lower flows are desirable. However, in microgravity, lower flows are dominated by forces other than inertia (like the capillary force). It is of paramount interest to investigate limits of low flows beyond which the flow is inertial enough to be gravity independent. One of the objectives of the Flow Boiling and Condensation Flight Experiment sets to investigate these limits for flow boiling and condensation. A two-phase flow loop consisting of a Flow Boiling Module and two Condensation Modules has been developed to experimentally study flow boiling condensation heat transfer in the reduced gravity environment provided by the reduced gravity platform. This effort supports the development of a flow boiling and condensation facility for the International Space Station (ISS). The closed loop test facility is designed to deliver the test fluid, FC-72 to the inlet of any one of the test modules at specified thermodynamic and flow conditions. The zero-g-aircraft tests will provide subcooled and saturated flow boiling critical heat flux and flow condensation heat transfer data over wide range of flow velocities. Additionally, these tests will verify the performance of all gravity sensitive components, such as evaporator, condenser and accumulator associated with the two-phase flow loop. We will present in this paper the breadboard development and testing results which consist of detailed performance evaluation of the heater and condenser combination in reduced and normal gravity. We will also present the design of the reduced gravity aircraft rack and the results of the ground flow boiling heat transfer testing performed with the Flow Boiling Module that is designed to investigate flow boiling heat transfer and

  5. Internal fluid flow management analysis for Clinch River Breeder Reactor Plant sodium pumps

    International Nuclear Information System (INIS)

    Cho, S.M.; Zury, H.L.; Cook, M.E.; Fair, C.E.

    1978-12-01

    The Clinch River Breeder Reactor Plant (CRBRP) sodium pumps are currently being designed and the prototype unit is being fabricated. In the design of these large-scale pumps for elevated temperature Liquid Metal Fast Breeder Reactor (LMFBR) service, one major design consideration is the response of the critical parts to severe thermal transients. A detailed internal fluid flow distribution analysis has been performed using a computer code HAFMAT, which solves a network of fluid flow paths. The results of the analytical approach are then compared to the test data obtained on a half-scale pump model which was tested in water. The details are presented of pump internal hydraulic analysis, and test and evaluation of the half-scale model test results

  6. Ideal Internal Carotid Artery Trapping Technique without Bypass in a Patient with Insufficient Collateral Flow

    OpenAIRE

    Chung, Joon Ho; Shin, Yong Sam; Lim, Yong Cheol; Park, Minjung

    2009-01-01

    Internal carotid artery (ICA) trapping can be used for treating intracranial giant aneurysm, blood blister-like aneurysms and ICA rupture during the surgery. We present a novel ICA trapping technique which can be used with insufficient collaterals flow via anterior communicating artery (AcoA) and posterior communicating artery (PcoA). A patient was admitted with severe headache and the cerebral angiography demonstrated a typical blood blister-like aneurysm at the contralateral side of PcoA. F...

  7. Internal hydraulic control in the Little Belt, Denmark - observations of flow configurations and water mass formation

    Science.gov (United States)

    Holtegaard Nielsen, Morten; Vang, Torben; Chresten Lund-Hansen, Lars

    2017-12-01

    Internal hydraulic control, which occurs when stratified water masses are forced through an abrupt constriction, plays an enormous role in nature on both large and regional scales with respect to dynamics, circulation, and water mass formation. Despite a growing literature on this subject surprisingly few direct observations have been made that conclusively show the existence of and the circumstances related to internal hydraulic control in nature. In this study we present observations from the Little Belt, Denmark, one of three narrow straits connecting the Baltic Sea and the North Sea. The observations (comprised primarily of along-strait, detailed transects of salinity and temperature; continuous observations of flow velocity, salinity, and temperature at a permanent station; and numerous vertical profiles of salinity, temperature, fluorescence, and flow velocity in various locations) show that internal hydraulic control is a frequently occurring phenomenon in the Little Belt. The observations, which are limited to south-going flows of approximately two-layered water masses, show that internal hydraulic control may take either of two configurations, i.e. the lower or the upper layer being the active, accelerating one. This is connected to the depth of the pycnocline on the upstream side and the topography, which is both deepening and contracting toward the narrow part of the Little Belt. The existence of two possible flow configurations is known from theoretical and laboratory studies, but we believe that this has never been observed in nature and reported before. The water masses formed by the intense mixing, which is tightly connected with the presence of control, may be found far downstream of the point of control. The observations show that these particular water masses are associated with chlorophyll concentrations that are considerably higher than in adjacent water masses, showing that control has a considerable influence on the primary production and

  8. Internal combustion engine exhaust pipe flow simulation. Part I: theoretical aspects

    OpenAIRE

    Juan Miguel Mantilla; Camilo Andrés Falla; Jorge Arturo Gómez

    2010-01-01

    Unsteady gas flow theory can be used for simulating a spark ignition internal combustion engine’s exhaust system, using pressure waves. The method explained here is based on the discretization of interpolated spaces (called meshes) which are located throughout the whole length of the exhaust pipe, irrespective of its form or size. The most important aspects of this theory are theoretically explored, such as pressure wave movement and shock and their application to cases found in re...

  9. Internal combustion engine exhaust pipe flow simulation. Part I: theoretical aspects

    OpenAIRE

    Juan Miguel Mantilla; Camilo Andrés Falla; Jorge Arturo Gómez

    2009-01-01

    Unsteady gas flow theory can be used for simulating a spark ignition internal combustion engine’s exhaust system, using pressure waves. The method explained here is based on the discretization of interpolated spaces (called meshes) which are located throughout the whole length of the exhaust pipe, irrespective of its form or size. The most important aspects of this theory are theoretically explored, such as pressure wave movement and shock and their application to cases found in real engines’...

  10. Large Matched-Index-of-Refraction (MIR) Flow Systems for International Collaboration In Fluid Mechanics

    International Nuclear Information System (INIS)

    McEligot, Donald M.; Becker, Stefan; McIlroy, Hugh M. Jr.

    2010-01-01

    In recent international collaboration, INL and Uni. Erlangen have developed large MIR flow systems which can be ideal for joint graduate student education and research. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in complex passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The MIR technique is not new itself; others employed it earlier. The innovation of these MIR systems is their large size relative to previous experiments, yielding improved spatial and temporal resolution. This report will discuss the benefits of the technique, characteristics of the systems and some examples of their applications to complex situations. Typically their experiments have provided new fundamental understanding plus benchmark data for assessment and possible validation of computational thermal fluid dynamic codes.

  11. Large Matched-Index-of-Refraction (MIR) Flow Systems for International Collaboration In Fluid Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Donald M. McEligot; Stefan Becker; Hugh M. McIlroy, Jr.

    2010-07-01

    In recent international collaboration, INL and Uni. Erlangen have developed large MIR flow systems which can be ideal for joint graduate student education and research. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in complex passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The MIR technique is not new itself; others employed it earlier. The innovation of these MIR systems is their large size relative to previous experiments, yielding improved spatial and temporal resolution. This report will discuss the benefits of the technique, characteristics of the systems and some examples of their applications to complex situations. Typically their experiments have provided new fundamental understanding plus benchmark data for assessment and possible validation of computational thermal fluid dynamic codes.

  12. A method for gear fatigue life prediction considering the internal flow field of the gear pump

    Science.gov (United States)

    Shen, Haidong; Li, Zhiqiang; Qi, Lele; Qiao, Liang

    2018-01-01

    Gear pump is the most widely used volume type hydraulic pump, and it is the main power source of the hydraulic system. Its performance is influenced by many factors, such as working environment, maintenance, fluid pressure and so on. It is different from the gear transmission system, the internal flow field of gear pump has a greater impact on the gear life, therefore it needs to consider the internal hydraulic system when predicting the gear fatigue life. In this paper, a certain aircraft gear pump as the research object, aim at the typical failure forms, gear contact fatigue, of gear pump, proposing the prediction method based on the virtual simulation. The method use CFD (Computational fluid dynamics) software to analyze pressure distribution of internal flow field of the gear pump, and constructed the unidirectional flow-solid coupling model of gear to acquire the contact stress of tooth surface on Ansys workbench software. Finally, employing nominal stress method and Miner cumulative damage theory to calculated the gear contact fatigue life based on modified material P-S-N curve. Engineering practice show that the method is feasible and efficient.

  13. Effect of wall wettability on flow characteristics of gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Uematsu, Junichi; Abe, Kazuya; Hazuku, Tatsuya; Takamasa, Tomoji; Hibiki, Takashi

    2007-01-01

    To evaluate the effect of surface wettability in pipe wall on flow characteristics in a vertical upward gas-liquid to-phase flow, visualization study was performed using three test pipes, namely an acrylic pipe, a hydrophilic pipe, a hydrophobic pipe. Such basic flow characteristics as flow patterns and void fraction were investigated in these three pipes. In the hydrophilic pipe, the slug flow-to-churn flow transition boundary was shifted to higher gas velocity condition at a given liquid velocity, whereas the churn flow-to-annular flow transition boundary was shifted to lower gas velocity condition at a given liquid velocity. In the hydrophobic pipe, the inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, whereas the droplet flow regime was observed in the region where the annular flow regime was observed in the acrylic pipe. At high-gas flow rate condition, the mean void fraction in the hydrophobic pipe took relatively higher value to that in the acrylic pipe. (author)

  14. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    Energy Technology Data Exchange (ETDEWEB)

    Stankovic, Zoran [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Roessle, Martin; Schultheiss, Michael [University Medical Center Freiburg, Department of Gastroenterology, Freiburg (Germany); Euringer, Wulf; Langer, Mathias [University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Salem, Riad; Barker, Alex; Carr, James; Collins, Jeremy D. [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States)

    2015-09-15

    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  15. Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry.

    Science.gov (United States)

    Xiao, Feng; Lam, Kit Ming; Li, Xiao-yan

    2013-05-01

    An advanced particle-tracking and flow-visualization technology, particle image velocimetry (PIV), was utilized to investigate the hydrodynamic properties of large aggregates in water. The laser-based PIV system was used together with a settling column to capture the streamlines around two types of aggregates: latex particle aggregates and activated sludge (AS) flocs. Both types of the aggregates were highly porous and fractal with fractal dimensions of 2.13±0.31 for the latex particle aggregates (1210-2144 μm) and 1.78±0.24 for the AS flocs (1265-3737 μm). The results show that PIV is a powerful flow visualization technique capable of determining flow field details at the micrometer scale around and through settling aggregates and flocs. The PIV streamlines provided direct experimental proof of internal flow through the aggregate interiors. According to the PIV images, fluid collection efficiency ranged from 0.052 to 0.174 for the latex particle aggregates and from 0.008 to 0.126 for AS flocs. AS flocs are apparently less permeable than the particle aggregates, probably due to the extracellular polymeric substances (EPSs) produced by bacteria clogging the pores within the flocs. The internal permeation of fractal aggregates and bio-flocs would enhance flocculation between particles and material transport into the aggregates. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Surgical dissection of the internal carotid artery under flow control by proximal vessel clamping reduces embolic infarcts during carotid endarterectomy.

    Science.gov (United States)

    Yoshida, Kazumichi; Kurosaki, Yoshitaka; Funaki, Takeshi; Kikuchi, Takayuki; Ishii, Akira; Takahashi, Jun C; Takagi, Yasushi; Yamagata, Sen; Miyamoto, Susumu

    2014-01-01

    To evaluate the efficacy of flow control of the internal carotid artery (ICA) by the clamping of the common carotid artery, external carotid artery, and superior thyroid artery during surgical ICA dissection to reduce ischemic complications after carotid endarterectomy (CEA). Sixty-seven patients (59 men; age, 70.5 ± 6.2 years) who underwent CEA by the same surgeon were retrospectively studied. Both conventional CEA (n = 29) and flow-control CEA (n = 38) were performed with the patient under general anesthesia and with the use of somatosensory-evoked potential and near-infrared spectroscopy monitoring as a guide for selective shunting. The number of new postoperative infarcts was assessed with preoperative and postoperative diffusion-weighted images (DWIs) obtained within 3 days of surgery. In addition to surgical technique, the effects of the following factors on new infarcts also were examined: age, side of ICA stenosis, high-grade stenosis, symptoms, and application of shunting. New postoperative DWI lesions were observed in 7 of 67 patients (10.4%), and none of them was symptomatic. With respect to operative technique, the incidence rate of DWI spots was significantly lower in the flow-control group (2.6%) than in the conventional group (20.7%), odds ratio: 0.069; 95% confidence interval: 0.006-0.779; P = 0.031). On multiple logistic regression analysis, age, side of ICA stenosis, high-grade stenosis, symptoms, and the use of internal shunting did not have significant effects on new postoperative DWI lesions, whereas technique did have an effect. The proximal flow-control technique for CEA helps avoid embolic complications during surgical ICA dissection. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Effect of flow conditions on flow accelerated corrosion in pipe bends

    International Nuclear Information System (INIS)

    Mazhar, H.; Ching, C.Y.

    2015-01-01

    Flow Accelerated Corrosion (FAC) in piping systems is a safety and reliability problem in the nuclear industry. In this study, the pipe wall thinning rates and development of surface roughness in pipe bends are compared for single phase and two phase annular flow conditions. The FAC rates were measured using the dissolution of test sections cast from gypsum in water with a Schmidt number of 1280. The change in location and levels of maximum FAC under single phase and two phase flow conditions are examined. The comparison of the relative roughness indicates a higher effect for the surface roughness in single phase flow than in two phase flow. (author)

  18. The Logistics Performance Effect in International Trade

    Directory of Open Access Journals (Sweden)

    Azmat Gani

    2017-12-01

    Full Text Available The continuous growth in world trade depends on the efficiency of trade support structures such as the logistics services. Despite logistics integral role in supporting commercial activities, there has generally been a low level of analysis and trade policy research focus from trade practitioners. This paper explores the effect of logistics performance in international trade. The analysis draws on overall logistics performance as well as disaggregated measures of logistics specificities data for a large sample of countries. The empirical analysis involved the estimation of standard export and import equations incorporating measures of logistics performance. The findings show that the overall logistics performance is positively and statistically significantly correlated with exports and imports. The analysis is also extended by investigating if logistics specificities mattered for international trade. The findings reveal that several dimensions capturing logistics performance have statistically significant and positive effect, mostly on exports. The main policy implication is that continuous investment in logistics infrastructure and services can positively impact international trade.

  19. By-pass flows and temperature distribution in a hot gas duct internally insulated by carbon stone

    International Nuclear Information System (INIS)

    Konuk, A.A.

    1979-01-01

    A mathematical model has been developed to calculate by-pass flows and temperature distribution in a hot gas duct internally insulated by carbon stone rings. The equations of conservation of mass and momentum are solved for a piping system to obtain axial and radial by-pass velocities. The energy equation is solved next by a marching method to obtain the radial temperature distribution along the duct. The results, although qualitative due to simplifications in the model, are useful to study the effects of duct geometry on its performance. (Author) [pt

  20. Effect of internal elements of the steam turbine exhaust hood on losses

    Directory of Open Access Journals (Sweden)

    Tajč Ladislav

    2012-04-01

    Full Text Available The document deals with the flow in the exhaust hood of a single flow steam turbine. The effect of the shape of the external case of the hood and the position and dimensions of the internal reinforcements on the energy loss coefficient is evaluated. Using this coefficient, it is possible to determine the gained or lost output in the diffuser and the entire exhaust hood at a known flow and efficiency of the last stage. Flow research in the exhaust hood was performed especially using numeric simulations; some variants were verified experimentally in the aerodynamic wind tunnel.

  1. Effect of a flow-corrective insert on the flow pattern in a pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yu; Gui, Nan; Yang, Xingtuan [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); Tu, Jiyuan [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); School of Aerospace, Mechanical & Manufacturing Engineering, RMIT University, Melbourne 3083, VIC (Australia); Jiang, Shengyao, E-mail: shengyaojiang@sina.com [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2016-04-15

    Highlights: • Effect of an insert on improving flow uniformity and eliminating stagnant zone is studied. • Three values concerned with the stagnant zone, radial uniformity and flow sequence are used. • Outlet diameter is a critical parameter that determines balancing mechanism of the insert. • Height/location is varied to let the insert work in unbalanced region and avoid adverse effect. - Abstract: A flow-corrective insert is adopted in the pebble-bed high temperature gas-cooled reactor (HTGR) to improve flow performance of the pebble flow for the first time. 3D discrete element method (DEM) modeling is employed to study this slow and dense granular flow. It is verified that locating a properly designed insert in the bed can help transform unsatisfactory flow field to the preferred flow pattern for pebble bed reactors. Three characteristic values on the stagnant zone, radial uniformity and flow sequence of pebble flow are defined to evaluate uniformity of the overall flow field quantitatively. The results demonstrate that the pebble bed equipped with an insert performs better than normal beds from all these three aspects. Moreover, based on numerical experiments, several universal tips for insert design on height, location and outlet diameter are suggested.

  2. Internal Flow Simulation of Enhanced Performance Solid Rocket Booster for the Space Transportation System

    Science.gov (United States)

    Ahmad, Rashid A.; McCool, Alex (Technical Monitor)

    2001-01-01

    An enhanced performance solid rocket booster concept for the space shuttle system has been proposed. The concept booster will have strong commonality with the existing, proven, reliable four-segment Space Shuttle Reusable Solid Rocket Motors (RSRM) with individual component design (nozzle, insulator, etc.) optimized for a five-segment configuration. Increased performance is desirable to further enhance safety/reliability and/or increase payload capability. Performance increase will be achieved by adding a fifth propellant segment to the current four-segment booster and opening the throat to accommodate the increased mass flow while maintaining current pressure levels. One development concept under consideration is the static test of a "standard" RSRM with a fifth propellant segment inserted and appropriate minimum motor modifications. Feasibility studies are being conducted to assess the potential for any significant departure in component performance/loading from the well-characterized RSRM. An area of concern is the aft motor (submerged nozzle inlet, aft dome, etc.) where the altered internal flow resulting from the performance enhancing features (25% increase in mass flow rate, higher Mach numbers, modified subsonic nozzle contour) may result in increased component erosion and char. To assess this issue and to define the minimum design changes required to successfully static test a fifth segment RSRM engineering test motor, internal flow studies have been initiated. Internal aero-thermal environments were quantified in terms of conventional convective heating and discrete phase alumina particle impact/concentration and accretion calculations via Computational Fluid Dynamics (CFD) simulation. Two sets of comparative CFD simulations of the RSRM and the five-segment (IBM) concept motor were conducted with CFD commercial code FLUENT. The first simulation involved a two-dimensional axi-symmetric model of the full motor, initial grain RSRM. The second set of analyses

  3. Effects of Electron Flow Current Density on Flow Impedance of Magnetically Insulated Transmission Lines

    International Nuclear Information System (INIS)

    He Yong; Zou Wen-Kang; Song Sheng-Yi

    2011-01-01

    In modern pulsed power systems, magnetically insulated transmission lines (MITLs) are used to couple power between the driver and the load. The circuit parameters of MITLs are well understood by employing the concept of flow impedance derived from Maxwell's equations and pressure balance across the flow. However, the electron density in an MITL is always taken as constant in the application of flow impedance. Thus effects of electron flow current density (product of electron density and drift velocity) in an MITL are neglected. We calculate the flow impedances of an MITL and compare them under three classical MITL theories, in which the electron density profile and electron flow current density are different from each other. It is found that the assumption of constant electron density profile in the calculation of the flow impedance is not always valid. The electron density profile and the electron flow current density have significant effects on flow impedance of the MITL. The details of the electron flow current density and its effects on the operation impedance of the MITL should be addressed more explicitly by experiments and theories in the future. (nuclear physics)

  4. The effect of ultrasound on arterial blood flow: 1. Steady fully developed flow

    International Nuclear Information System (INIS)

    Bestman, A.R.

    1990-12-01

    The paper models the effects of ultrasound heating of the tissues and the resultant perturbation on blood flow in the arteries and veins. It is assumed that the blood vessel is rigid and the undisturbed flow is fully developed. Acoustical perturbation on this Poiseuille flow, for the general three-dimensional flow with heat transfer in an infinitely long pipe is considered. Closed form analytical solutions are obtained to the problem. It is discovered that the effects of the ultrasound heating are concentrated at the walls of the blood vessels. (author). 4 refs

  5. Inertia effects in rheometrical flow systems

    NARCIS (Netherlands)

    Waterman, H.A.

    1976-01-01

    The flow field of a linear viscoelastic material in the orthogonal rheometer, taking fluid inertia into account, has been studied theoretically and an exact solution is given. The flow field of a Newtonian liquid is included in this solution as a special case. The forces on the plates are readily

  6. Information security policy: contributions from internal marketing for its effectiveness

    Directory of Open Access Journals (Sweden)

    Cristiane Ellwanger

    2012-06-01

    Full Text Available Protecting sources of information has become a great challenge to the organizations, due to the advance of the information technologies, the integration between them and the constant stream of information that flows through the communication networks. The establishment of an Information Security Policy – PSI may resolve a part of the problems related to security, but it cannot totally solve them, since the human resources present in the internal environment of the organizations may spoil the effectiveness of the PSI. Given the importance of the human aspects in the context of the information security, the present work discusses the use of internal marketing as a management strategy in order to obtain or reestablish the commitment of the users to the principles defined in the PSI, and demonstrates, through an experimental research, the impact of using internal marketing techniques to the effectiveness of that policy. The results of this experiment make quantitatively evident how relevant the use of these techniques may be in order to have the procedures described in the PSI actually carried out by the users, and demonstrates a 402,4% increase in the support to the information security policy, considering the procedures indicated in the PSI that were totally executed.

  7. Frictional pressure drop of high pressure steam-water two-phase flow in internally helical ribbed tubes

    International Nuclear Information System (INIS)

    Tingkuan, C.; Xuanzheng, C.

    1987-01-01

    It is well known that the internally helical ribbed tubes are effective in suppressing the dry-out in boiling tubes at high pressures, so they are widely used as furnace water wall tubes in modern large steam power boilers. Design of the boilers requires the data on frictional pressure drop characteristics of the ribbed tubes, but they are not sufficient now. This paper describes the experimental results on the adiabatic frictional pressure drop in both horizontal ribbed tubes with measured mean inside diameter of 11.69 mm and 35.42 mm at high pressure from 10 to 21 MPa, mass flow rate from 350 to 3800 kg/m/sup 2/s and steam quality from 0 to 1 in our high pressure electrically heated water loop. Simultaneously, both smooth tubes under the same conditions for comparison. Based on the tests the correlation for determining the frictional pressure drop of internally ribbed tubes are proposed

  8. The effect of sympathectomy on bone blood flow in man

    International Nuclear Information System (INIS)

    Lahtinen, T.; Alhava, E.M.; Hyoedynmaa, S.; Hendolin, H.; Oksala, I.

    1982-01-01

    The effect of lumbar sympathectomy on bone blood flow was measured in seven patients with a Xe-133 washout method. On the third postoperative day there was a significant increase of blood flow in the proximal femur and a slight increase in the proximal tibia. Two months after the operation blood flow in the proximal part of the femur was no more significantly increased but in the proximal tibia there was a significant increase. The study suggests that the positive effect of sympathectomy on bone blood flow may be of value in cases where the increase of blood flow to peripheral bones is required

  9. Boltzmann rovibrational collisional coarse-grained model for internal energy excitation and dissociation in hypersonic flows.

    Science.gov (United States)

    Munafò, A; Panesi, M; Magin, T E

    2014-02-01

    A Boltzmann rovibrational collisional coarse-grained model is proposed to reduce a detailed kinetic mechanism database developed at NASA Ames Research Center for internal energy transfer and dissociation in N(2)-N interactions. The coarse-grained model is constructed by lumping the rovibrational energy levels of the N(2) molecule into energy bins. The population of the levels within each bin is assumed to follow a Boltzmann distribution at the local translational temperature. Excitation and dissociation rate coefficients for the energy bins are obtained by averaging the elementary rate coefficients. The energy bins are treated as separate species, thus allowing for non-Boltzmann distributions of their populations. The proposed coarse-grained model is applied to the study of nonequilibrium flows behind normal shock waves and within converging-diverging nozzles. In both cases, the flow is assumed inviscid and steady. Computational results are compared with those obtained by direct solution of the master equation for the rovibrational collisional model and a more conventional multitemperature model. It is found that the proposed coarse-grained model is able to accurately resolve the nonequilibrium dynamics of internal energy excitation and dissociation-recombination processes with only 20 energy bins. Furthermore, the proposed coarse-grained model provides a superior description of the nonequilibrium phenomena occurring in shock heated and nozzle flows when compared with the conventional multitemperature models.

  10. Vibrational response of a rectangular duct of finite length excited by a turbulent internal flow

    Science.gov (United States)

    David, Antoine; Hugues, Florian; Dauchez, Nicolas; Perrey-Debain, Emmanuel

    2018-05-01

    Gas transport ductwork in industrial plants or air conditioning networks can be subject to vibrations induced by the internal flow. Most studies in this matter have been carried out on circular ducts. This paper focuses specifically on the vibratory response of a rectangular duct of finite length excited by an internal turbulent flow. A semi-analytical model taking into account the modal response of the structure due to both aerodynamic and acoustic contributions is derived. The aerodynamic component of the excitation is applied on the basis of Corcos model where the power spectral density of the wall pressure is determined experimentally. The acoustic component is based on the propagating modes in the duct where the acoustic modal contribution are extracted via cross-spectral densities. The vibrational response is given for a 0.2 × 0.1 × 0.5 m3 duct made of 3 mm steel plates excited by 20 m/s or 30 m/s flows. Comparisons between experimental results and numerical predictions show a good agreement. The competition between acoustic and aerodynamic components is highlighted.

  11. Ergonomics perspective for identifying and reducing internal operative flow disruption for laparoscopic urological surgery.

    Science.gov (United States)

    Al-Hakim, Latif; Xiao, Jiaquan; Sengupta, Shomik

    2017-12-01

    The aim of this study is to examine operative flow disruption that occurs inside the surgical field, (internal operative flow disruption (OFD)), during urological laparoscopies, and to relate those events to external ergonomics environment in terms of monitor location, level of instruments' handles, and location of surgical team members. According to the our best knowledge, this is the first study of its kind. A combination of real and video-aided observational study was conducted in the operating rooms at hospitals in Australia and China. Brain storming sessions were first conducted to identify the main internal OFD events, and the observable reasons, potential external, and latent ergonomic factors were listed. A prospective observational study was then conducted. The observer's records and the related video records of internal surgical fields were analysed. Procedures were categorised into groups based on similarity in ergonomics environment. The mapping process revealed 39 types of internal OFD events resulted from six reasons. A total of 24 procedures were selected and arranged into two groups, each with twelve procedures. Group A was carried out under satisfactory ergonomics environment, while Group B was conducted under unsatisfactory ergonomics environment. A total of 1178 OFD events were detected delaying the total observed operative times (2966 min) by 220 min (7.43%). Average OFD/h in group A was less than 15, while in group B about 29 OFD/h. There are two main latent ergonomics factors affecting the surgeon's performance; non-physiological posture and long-period static posture. The delays and number of internal OFD were nearly doubled where procedures were conducted under unsatisfactory external ergonomics environment. Some events such as stopping operation and irrelevant conversations during long procedures may have a positive influence on the surgeon's performance.

  12. On the relationship between competitive flow and FFT analysis of the flow waves in the left internal mammary artery graft in the process of CABG.

    Science.gov (United States)

    Mao, Boyan; Wang, Wenxin; Zhao, Zhou; Zhao, Xi; Li, Lanlan; Zhang, Huixia; Liu, Youjun

    2016-12-28

    During coronary artery bypass grafting (CABG), the ratio of powers of the fundamental frequency and its first harmonic (F0/H1) in fast Fourier transformation (FFT) analysis of the graft's flow waves has been used in the field of evaluation of the patency in anastomosis. But there is no report about using the FFT method to evaluate the magnitude of competitive flow. This study is aiming at exploring the relationship between competitive flow and FFT analysis of the flow waves in left internal mammary artery (LIMA) graft, and finding a new method to evaluate the magnitude of competitive flow. At first, establishing the CABG multiscale models of different stenosis in left anterior descending artery (LAD) to get different magnitude of competitive flows. Then, calculating the models by ANSYS-CFX and getting the flow waves in LIMA. Finally, analyzing the flow waves by FFT method and comparing the FFT results with the magnitude of competitive flow. There is no relationship between competitive flow and F0/H1. As for F0/H2 and F0/H3, they both increase with the reduction of the stenosis in LAD. But the increase of F0/H3 is not obviously enough and it can't identify the significant competitive flow clearly, so it can't be used as the evaluation index. It is found that F0/H2 increases obviously with the increase of the competitive flow and can identify the significant competitive flow. The FFT method can be used in the evaluation of competitive flow and the F0/H2 is the ideal index. High F0/H2 refers to the significant competitive flow. This method can be used during CABG to avoid the risk of competitive flow.

  13. Chaotic Flows Correlation effects and coherent structures

    CERN Document Server

    Bakunin, Oleg G

    2011-01-01

    The book introduces readers to and summarizes the current ideas and theories about the basic mechanisms for transport in chaotic flows. Typically no single paradigmatic approach exists as this topic is relevant for fields as diverse as plasma physics, geophysical flows and various branches of engineering. Accordingly, the dispersion of matter in chaotic or turbulent flows is analyzed from different perspectives. Partly based on lecture courses given by the author, this book addresses both graduate students and researchers in search of a high-level but approachable and broad introduction to the topic.

  14. Simulation model for centrifugal pump in flow networks based on internal characteristics

    International Nuclear Information System (INIS)

    Sun, Ji-Lin; Xue, Ruo-Jun; Peng, Min-Jun

    2018-01-01

    For the simulation of centrifugal pump in flow network system, in general three approaches can be used, the fitting model, the numerical method and the internal characteristics model. The fitting model is simple and rapid thus widely used. The numerical method can provide more detailed information in comparison with the fitting model, but increases implementation complexity and computational cost. In real-time simulations of flow networks, to simulate the condition out of the rated condition, especially for the volume flow rate, which the accuracy of fitting model is incredible, a new method for simulating centrifugal pumps was proposed in this research. The method based on the theory head and hydraulic loss in centrifugal pumps, and cavitation is also to be considered. The simulation results are verified with experimental benchmark data from an actual pump. The comparison confirms that the proposed method could fit the flow-head curves well, and the responses of main parameters in dynamic-state operations are consistent with theoretical analyses.

  15. Simulation of water flow in fractured porous medium by using discretized virtual internal bond

    Science.gov (United States)

    Peng, Shujun; Zhang, Zhennan; Li, Chunfang; He, Guofu; Miao, Guoqing

    2017-12-01

    The discretized virtual internal bond (DVIB) is adopted to simulate the water flow in fractured porous medium. The intact porous medium is permeable because it contains numerous micro cracks and pores. These micro discontinuities construct a fluid channel network. The representative volume of this fluid channel network is modeled as a lattice bond cell with finite number of bonds in statistical sense. Each bond serves as a fluid channel. In fractured porous medium, many bond cells are cut by macro fractures. The conductivity of the fracture facet in a bond cell is taken over by the bonds parallel to the flow direction. The equivalent permeability and volumetric storage coefficient of a micro bond are calibrated based on the ideal bond cell conception, which makes it unnecessary to consider the detailed geometry of a specific element. Such parameter calibration method is flexible and applicable to any type of element. The accuracy check results suggest this method has a satisfying accuracy in both the steady and transient flow simulation. To simulate the massive fractures in rockmass, the bond cells intersected by fracture are assigned aperture values, which are assumed random numbers following a certain distribution law. By this method, any number of fractures can be implicitly incorporated into the background mesh, avoiding the setup of fracture element and mesh modification. The fracture aperture heterogeneity is well represented by this means. The simulation examples suggest that the present method is a feasible, simple and efficient approach to the numerical simulation of water flow in fractured porous medium.

  16. A SPECT study in internal carotid artery occlusion: Discrepancies between flow image and neurologic deficits

    International Nuclear Information System (INIS)

    Moriwaki, H.; Hougaku, H.; Matsuda, I.; Kusunoki, M.; Shirai, J.

    1989-01-01

    A SPECT (single photon emission computed tomography) study in internal carotid artery (ICA) occlusion was performed in 6 patients. The validity of iodoamphetamine (IMP) SPECT study in the evaluation of cerebral blood flow (CBF) or neurologic function is still controversial. In this study, the authors showed several cases in whom SPECT images of brain were not compatible with their neurologic deficits. In 2 typical cases, a large low-density area was observed in the non-dominant hemisphere in computed tomography (CT) scan, but no apparent motor-sensory deficits in left limbs were present. In these patients, SPECT study also revealed flow reduction in the affected side of the brain. So there was a possibility that an IMP brain image could not always reflect CBF, which maintains neurologic function of the brain

  17. Internal combustion engine exhaust pipe flow simulation. Part I: theoretical aspects

    Directory of Open Access Journals (Sweden)

    Juan Miguel Mantilla

    2009-01-01

    Full Text Available Unsteady gas flow theory can be used for simulating a spark ignition internal combustion engine’s exhaust system, using pressure waves. The method explained here is based on the discretization of interpolated spaces (called meshes which are located throughout the whole length of the exhaust pipe, irrespective of its form or size. The most important aspects of this theory are theoretically explored, such as pressure wave movement and shock and their application to cases found in real engines’ exhaust pipes. This work also considers how the simulation must be made, based on the previous exploration. The results (presented as e- quations in this first paper show the great influence exerted by pressure wave movement on flow through the engine and there- fore on its final performance.

  18. Influence of internal channel geometry of gas turbine blade on flow structure and heat transfer

    Science.gov (United States)

    Szwaba, Ryszard; Kaczynski, Piotr; Telega, Janusz; Doerffer, Piotr

    2017-12-01

    This paper presents the study of the influence of channel geometry on the flow structure and heat transfer, and also their correlations on all the walls of a radial cooling passage model of a gas turbine blade. The investigations focus on the heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of internal cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include a corner fillets, ribs with fillet radii and a special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which has very realistic features.

  19. The effect of debris-flow composition on runout distance

    Science.gov (United States)

    de Haas, Tjalling; Braat, Lisanne; Leuven, Jasper; Lokhorst, Ivar; Kleinhans, Maarten

    2015-04-01

    Estimating runout distance is of major importance for the assessment and mitigation of debris-flow hazards. Debris-flow runout distance depends on debris-flow composition and topography, but state-of-the-art runout prediction methods are mainly based on topographical parameters and debris-flow volume, while composition is generally neglected or incorporated in empirical constants. Here we experimentally investigated the effect of debris-flow composition and topography on runout distance. We created the first small-scale experimental debris flows with self-formed levees, distinct lobes and morphology and texture accurately resembling natural debris flows. In general, the effect of debris-flow composition on runout distance was larger than the effect of topography. Enhancing channel slope and width, outflow plain slope, debris-flow size and water fraction leads to an increase in runout distance. However, runout distance shows an optimum relation with coarse-material and clay fraction. An increase in coarse-material fraction leads to larger runout distances by increased grain collisional forces and more effective levee formation, but too much coarse debris causes a large accumulation of coarse debris at the flow front, enhancing friction and decreasing runout. An increase in clay fraction initially enlarges the volume and viscosity of the interstitial fluid, liquefying the flow and enhancing runout, while a further increase leads to very viscous flows with high yield strength, reducing runout. These results highlight the importance and further need of research on the relation between debris-flow composition and runout distance. Our experiments further provide valuable insight on the effects of debris-flow composition on depositional mechanisms and deposit morphology.

  20. Pressure control of a proton beam-irradiated water target through an internal flow channel-induced thermosyphon.

    Science.gov (United States)

    Hong, Bong Hwan; Jung, In Su

    2017-07-01

    A water target was designed to enhance cooling efficiency using a thermosyphon, which is a system that uses natural convection to induce heat exchange. Two water targets were fabricated: a square target without any flow channel and a target with a flow channel design to induce a thermosyphon mechanism. These two targets had the same internal volume of 8 ml. First, visualization experiments were performed to observe the internal flow by natural convection. Subsequently, an experiment was conducted to compare the cooling performance of both water targets by measuring the temperature and pressure. A 30-MeV proton beam with a beam current of 20 μA was used to irradiate both targets. Consequently, the target with an internal flow channel had a lower mean temperature and a 50% pressure drop compared to the target without a flow channel during proton beam irradiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effects of confidence and anxiety on flow state in competition.

    Science.gov (United States)

    Koehn, Stefan

    2013-01-01

    Confidence and anxiety are important variables that underlie the experience of flow in sport. Specifically, research has indicated that confidence displays a positive relationship and anxiety a negative relationship with flow. The aim of this study was to assess potential direct and indirect effects of confidence and anxiety dimensions on flow state in tennis competition. A sample of 59 junior tennis players completed measures of Competitive State Anxiety Inventory-2d and Flow State Scale-2. Following predictive analysis, results showed significant positive correlations between confidence (intensity and direction) and anxiety symptoms (only directional perceptions) with flow state. Standard multiple regression analysis indicated confidence as the only significant predictor of flow. The results confirmed a protective function of confidence against debilitating anxiety interpretations, but there were no significant interaction effects between confidence and anxiety on flow state.

  2. Scattering of inhomogeneous circularly polarized optical field and mechanical manifestation of the internal energy flows

    DEFF Research Database (Denmark)

    Bekshaev, A. Ya; Angelsky, O. V.; Hanson, Steen Grüner

    2012-01-01

    between the forward- and backward-scattered momentum fluxes in the Rayleigh scattering regime appears due to the spin part of the internal energy flow in the incident beam. The transverse ponderomotive forces exerted on dielectric and conducting particles of different sizes are calculated and special......Based on the Mie theory and on the incident beam model via superposition of two plane waves, we analyze numerically the momentum flux of the field scattered by a spherical, nonmagnetic microparticle placed within the spatially inhomogeneous circularly polarized paraxial light beam. The asymmetry...

  3. Dynamic response of a system with internal heat sources cooled by a flowing incompressible fluid

    International Nuclear Information System (INIS)

    Georgescu, R.; Dobrescu, C.

    1975-01-01

    The paper investigates the dynamic temperature response of an incompressible fluid which cools a duct with internal heat sources sinusoidally oscillated. The analytical results utilise the Laplace transformation technique. The experimental and calculated results are obtained by transfer function approach. Comparison of the calculated with the experimental data indicates agreement from 6 to 24 percent for the amplitude and up to 30 degree for the phase-shift. All the calculated data are below the experimental ones. The analytical method of transfer function approach presents interest and may be utilized for the initial calculations giving good results for flow rates above 1000 kg per hour

  4. Experimental research on density wave oscillation of steam-water two-phase flow in parallel inclined internally ribbed pipes

    International Nuclear Information System (INIS)

    Gao Feng; Chen Tingkuan; Luo Yushan; Yin Fei; Liu Weimin

    2005-01-01

    At p=3-10 MPa, G=300-600 kg/(m 2 ·s), Δt sub =30-90 degree C, and q=0-190 kW/m 2 , the experiments on steam-water two-phase flow instabilities have been performed. The test sections are parallel inclined internally ribbed pipes with an outer diameter of φ38.1 mm, a wall thinkness of 7.5 mm, a obliquity of 19.5 and a length more than 15 m length. Based on the experimental results, the effects of pressure, mass velocity, inlet subcooling and asymmetrical heat flux on steam-water two-phase flow density wave oscillation were analyzed. The experimental results showed that the flow system were more stable as pressure increased. As an increase in mass velocity, critical heat flux increased but critical steam quality decreased. Inlet subcooling had a monotone effect on density wave oscillation, when inlet subcooling decreased, critical heat flux decreased. Under a certain working condition, critical heat flux on asymmetrically heating parallel pipes is higher than that on symmetrically heating parallel pipes, that means the system with symmetrically heating parallel pips was more stable. (authors)

  5. Effect of viscous dissipation on mixed convection flow in a vertical ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology .... third kind for flow over a flat plate and in the thermal entrance region of a rectangular channel. ... on mixed convection in a vertical channel using Robin boundary conditions was ... Hajmohammadi and Nourazar (2014) studied the effect of a thin gas layer in ...

  6. Effect of gas quantity on two-phase flow characteristics of a mixed-flow pump

    OpenAIRE

    Qiang Fu; Fan Zhang; Rongsheng Zhu; Xiuli Wang

    2016-01-01

    The inlet gas quantity has a great influence on the performance and inner flow characteristics of a mixed-flow pump. In this article, both numerical and experimental methods are used to carry out this research work. The effects under the steady gas volume fraction state and the transient gas quantity variation process on the mixed-flow pump are investigated and compared in detail. It could be concluded that the head of the mixed-flow pump shows slight decline at the low gas volume fraction st...

  7. Effect of flow on endothelial endocytosis of nanocarriers targeted to ICAM-1.

    Science.gov (United States)

    Bhowmick, Tridib; Berk, Erik; Cui, Xiumin; Muzykantov, Vladimir R; Muro, Silvia

    2012-02-10

    Delivery of drugs into the endothelium by nanocarriers targeted to endothelial determinants may improve treatment of vascular maladies. This is the case for intercellular adhesion molecule 1 (ICAM-1), a glycoprotein overexpressed on endothelial cells (ECs) in many pathologies. ICAM-1-targeted nanocarriers bind to and are internalized by ECs via a non-classical pathway, CAM-mediated endocytosis. In this work we studied the effects of endothelial adaptation to physiological flow on the endocytosis of model polymer nanocarriers targeted to ICAM-1 (anti-ICAM/NCs, ~180 nm diameter). Culturing established endothelial-like cells (EAhy926 cells) and primary human umbilical vein ECs (HUVECs) under 4 dyn/cm(2) laminar shear stress for 24 h resulted in flow adaptation: cell elongation and formation of actin stress fibers aligned to the flow direction. Fluorescence microscopy showed that flow-adapted cells internalized anti-ICAM/NCs under flow, although at slower rate versus non flow-adapted cells under static incubation (~35% reduction). Uptake was inhibited by amiloride, whereas marginally affected by filipin and cadaverine, implicating that CAM-endocytosis accounts for anti-ICAM/NC uptake under flow. Internalization under flow was more modestly affected by inhibiting protein kinase C, which regulates actin remodeling during CAM-endocytosis. Actin recruitment to stress fibers that maintain the cell shape under flow may delay uptake of anti-ICAM/NCs under this condition by interfering with actin reorganization needed for CAM-endocytosis. Electron microscopy revealed somewhat slow, yet effective endocytosis of anti-ICAM/NCs by pulmonary endothelium after i.v. injection in mice, similar to that of flow-adapted cell cultures: ~40% (30 min) and 80% (3 h) internalization. Similar to cell culture data, uptake was slightly faster in capillaries with lower shear stress. Further, LPS treatment accelerated internalization of anti-ICAM/NCs in mice. Therefore, regulation of endocytosis

  8. Flow-induced vibration of steam generator helical tubes subjected to external liquid cross flow and internal two-phase flow

    International Nuclear Information System (INIS)

    Jong Chull Jo; Myung Jo Jhung; Woong Sik Kim; Hho Jung Kim

    2005-01-01

    Full text of publication follows: This paper addresses the potential flow-induced vibration problems in a helically-coiled tube steam generator of integral-type nuclear reactor, of which the tubes are subjected to liquid cross flow externally and multi-phase flow externally. The thermal-hydraulic conditions of both tube side and shell side flow fields are predicted using a general purpose computational fluid dynamics code employing the finite volume element modeling. To get the natural frequency and corresponding mode shape of the helical type tubes with various conditions, a finite element analysis code is used. Based on the results of both helical coiled tube steam generator thermal-hydraulic and coiled tube modal analyses, turbulence-induced vibration and fluid-elastic instability analyses are performed. And then the potential for damages on the tubes due to either turbulence-induced vibration or fluid-elastic instability is assessed. In the assessment, special emphases are put on the detailed investigation for the effects of support conditions, coil diameter, and helix pitch on the modal, vibration amplitude and instability characteristics of tubes, from which a technical information and basis needed for designers and regulatory reviewers can be derived. (authors)

  9. Effect of mean flow on the interaction between turbulence and zonal flow

    International Nuclear Information System (INIS)

    Uzawa, Ken; Kishimoto, Yasuaki; Li Jiquan

    2006-01-01

    The effects of an external mean flow on the generation of zonal flow in drift wave turbulence are theoretically studied in terms of a modulational instability analysis. A dispersion relation for the zonal flow instability having complex frequency ω q =Ω q +iγ q is derived, which depends on the external mean flow's amplitude |φ f | and radial wave number k f . As an example, we chose an ion temperature gradient (ITG) turbulence-driven zonal flow as the mean flow acting on an electron temperature gradient (ETG) turbulence-zonal flow system. The growth rate of the zonal flow γ q is found to be suppressed, showing a relation γ q =γ q0 (1 - α|φ f | 2 k f 2 ), where γ q0 is the growth rate in the absence of mean flow and α is a positive numerical constant. This formula is applicable to a strong shearing regime where the zonal flow instability is stabilized at α|φ f 2 |k f 2 ≅ 1. Meanwhile, the suppression is accompanied by an increase of the real frequency |Ω q |. The underlying physical mechanism of the suppression is discussed. (author)

  10. Anthropogenic effect on avalanche and debris flow activity

    OpenAIRE

    S. A. Sokratov; Yu. G. Seliverstov; A. L. Shnyparkov; K. P. Koltermann

    2013-01-01

    The paper presents examples of the change in snow avalanches and debris flows activity due to the anthropogenic pressure on vegetation and relief. The changes in dynamical characteristics of selected snow avalanches and debris flows due to the anthropogenic activity are quantified. The conclusion is made that the anthropogenic effects on the snow avalanches and debris flows activity are more pronounced than the possible effects of the climate change. The necessity is expressed on the unavoida...

  11. Effects of Potential Lane-Changing Probability on Uniform Flow

    International Nuclear Information System (INIS)

    Tang Tieqiao; Huang Haijun; Shang Huayan

    2010-01-01

    In this paper, we use the car-following model with the anticipation effect of the potential lane-changing probability (Acta Mech. Sin. 24 (2008) 399) to investigate the effects of the potential lane-changing probability on uniform flow. The analytical and numerical results show that the potential lane-changing probability can enhance the speed and flow of uniform flow and that their increments are related to the density.

  12. ASSESSMENT OF CORRUPTION EFFECT ON FOREIGN INVESTMENT FLOWS

    OpenAIRE

    Sprinģis, Māris

    2011-01-01

    The purpose of the present paper is to investigate the impact of corruption on foreign direct investment (FDI) flows. Using data from the International Monetary Fund, Transparency International and United Nations conference about commerce and development data bases a cross-section econometric model was estimated to evaluate in which way and how strong corruption influence FDI inflows. Econometric modelling covers the period from year 2000 to 2007 and the data about 82 world countries that con...

  13. SRM Internal Flow Tests and Computational Fluid Dynamic Analysis. Volume 4; Cold Flow Analyses and CFD Analysis Capability Development

    Science.gov (United States)

    1995-01-01

    An evaluation of the effect of model inlet air temperature drift during a test run was performed to aid in the decision on the need for and/or the schedule for including heaters in the SRMAFTE. The Sverdrup acceptance test data was used to determine the drift in air temperature during runs over the entire range of delivered flow rates and pressures. The effect of this temperature drift on the model Reynolds number was also calculated. It was concluded from this study that a 2% change in absolute temperature during a test run could be adequately accounted for by the data analysis program. A handout package of these results was prepared and presented to ED35 management.

  14. Medical effects of internal contamination with uranium.

    Science.gov (United States)

    Duraković, A

    1999-03-01

    The purpose of this work is to present an outline of the metabolic pathways of uranium isotopes and compounds, medical consequences of uranium poisoning, and an evaluation of the therapeutic alternatives in uranium internal contamination. The chemical toxicity of uranium has been recognized for more than two centuries. Animal experiments and human studies are conclusive about metabolic adverse affects and nephro- toxicity of uranium compounds. Radiation toxicity of uranium isotopes has been recognized since the beginning of the nuclear era, with well documented evidence of reproductive and developmental toxicity, as well as mutagenic and carcinogenic consequences of uranium internal contamination. Natural uranium (238U), an alpha emitter with a half-life of 4.5x10(9) years, is one of the primordial substances of the universe. It is found in the earth's crust, combined with 235U and 234U, alpha, beta, and gamma emitters with respective half-lives of 7.1x10(8) and 2.5x10(5) years. A special emphasis of this paper concerns depleted uranium. The legacy of radioactive waste, environmental and health hazards in the nuclear industry, and, more recently, the military use of depleted uranium in the tactical battlefield necessitates further insight into the toxicology of depleted uranium. The present controversy over the radiological and chemical toxicity of depleted uranium used in the Gulf War warrants further experimental and clinical investigations of its effects on the biosphere and human organisms.

  15. Flow through internal elastic lamina affects shear stress on smooth muscle cells (3D simulations).

    Science.gov (United States)

    Tada, Shigeru; Tarbell, John M

    2002-02-01

    We describe a three-dimensional numerical simulation of interstitial flow through the medial layer of an artery accounting for the complex entrance condition associated with fenestral pores in the internal elastic lamina (IEL) to investigate the fluid mechanical environment around the smooth muscle cells (SMCs) right beneath the IEL. The IEL was modeled as an impermeable barrier to water flow except for the fenestral pores, which were assumed to be uniformly distributed over the IEL. The medial layer was modeled as a heterogeneous medium composed of a periodic array of cylindrical SMCs embedded in a continuous porous medium representing the interstitial proteoglycan and collagen matrix. Depending on the distance between the IEL bottom surface and the upstream end of the proximal layer of SMCs, the local shear stress on SMCs right beneath the fenestral pore could be more than 10 times higher than that on the cells far removed from the IEL under the conditions that the fenestral pore diameter and area fraction of pores were kept constant at 1.4 microm and 0.05, respectively. Thus these proximal SMCs may experience shear stress levels that are even higher than endothelial cells exposed to normal blood flow (order of 10 dyn/cm(2)). Furthermore, entrance flow through fenestral pores alters considerably the interstitial flow field in the medial layer over a spatial length scale of the order of the fenestral pore diameter. Thus the spatial gradient of shear stress on the most superficial SMC is noticeably higher than computed for endothelial cell surfaces.

  16. The effect of partial portal decompression on portal blood flow and effective hepatic blood flow in man: a prospective study.

    Science.gov (United States)

    Rosemurgy, A S; McAllister, E W; Godellas, C V; Goode, S E; Albrink, M H; Fabri, P J

    1995-12-01

    With the advent of transjugular intrahepatic porta-systemic stent shunt and the wider application of the surgically placed small diameter prosthetic H-graft portacaval shunt (HGPCS), partial portal decompression in the treatment of portal hypertension has received increased attention. The clinical results supporting the use of partial portal decompression are its low incidence of variceal rehemorrhage due to decreased portal pressures and its low rate of hepatic failure, possibly due to maintenance of blood flow to the liver. Surprisingly, nothing is known about changes in portal hemodynamics and effective hepatic blood flow following partial portal decompression. To prospectively evaluate changes in portal hemodynamics and effective hepatic blood flow brought about by partial portal decompression, the following were determined in seven patients undergoing HGPCS: intraoperative pre- and postshunt portal vein pressures and portal vein-inferior vena cava pressure gradients, intraoperative pre- and postshunt portal vein flow, and pre- and postoperative effective hepatic blood flow. With HGPCS, portal vein pressures and portal vein-inferior vena cava pressure gradients decreased significantly, although portal pressures remained above normal. In contrast to the significant decreases in portal pressures, portal vein blood flow and effective hepatic blood flow do not decrease significantly. Changes in portal vein pressures and portal vein-inferior vena cava pressure gradients are great when compared to changes in portal vein flow and effective hepatic blood flow. Reduction of portal hypertension with concomitant maintenance of hepatic blood flow may explain why hepatic dysfunction is avoided following partial portal decompression.

  17. Health effects of internally deposited radionuclides

    International Nuclear Information System (INIS)

    Raabe, Otto G.

    2008-01-01

    A comparative evaluation has been conducted of the ionizing radiation dose-response relationships in both human and laboratory animal studies involving internal deposition of radionuclides including alpha-emitters 226 Ra, 238 Pu, 239 Pu, and 241 Am and beta-emitters 90 Sr, 90 Y and 144 Ce. Intake routes included inhalation, injection, and ingestion. The preeminent importance of dose rate was revealed in this analysis. The lifetime effects of the ionizing radiation from internal emitters are described by three-dimensional dose rate/ time/response surfaces that compete with other causes of death during an individual's lifetime. Using maximum likelihood survival regression methods, the characteristic logarithmic slope for cancer induction was found to be about negative one-third for alpha-emitters or about negative two-thirds for beta-emitters. The relative biological effectiveness (RBE) of alpha versus beta radiations for cancer induction is a strong function of dose rate, near one at high dose rates and greater than 20 at low dose rates. The cumulative dose required to yield any level of induced-cancer risk is less at lower dose rates than at higher dose rates showing an apparent inverse-dose effect (up to a factor of 10 for high LET alpha radiation and a factor of 2 for low LET beta radiation). The competing risks of death associated with radiation injury, radiation-induced cancer, and natural aging are graphically shown using three-dimensional illustrations. At the higher average dose rates the principal deleterious effects are those associated with radiation-induced injury while at intermediate average dose rates radiation-induced cancer predominates. At the lower average dose rates the long latency time required for radiation-induced cancer may exceed natural life span, yielding an apparent lifespan effective threshold for death associated with radiation-induced cancer for cumulative doses to the target tissue below from 1.1 to 1.4 Gy for alpha-emitters or below

  18. Health effects of internally deposited radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Raabe, Otto G., E-mail: ograabe@ucdavis.edu [California Univ., Davis, CA (United States). Center for Health and the Environment

    2008-07-01

    A comparative evaluation has been conducted of the ionizing radiation dose-response relationships in both human and laboratory animal studies involving internal deposition of radionuclides including alpha-emitters {sup 226}Ra, {sup 238}Pu, {sup 239}Pu, and {sup 241}Am and beta-emitters {sup 90}Sr, {sup 90}Y and {sup 144}Ce. Intake routes included inhalation, injection, and ingestion. The preeminent importance of dose rate was revealed in this analysis. The lifetime effects of the ionizing radiation from internal emitters are described by three-dimensional dose rate/ time/response surfaces that compete with other causes of death during an individual's lifetime. Using maximum likelihood survival regression methods, the characteristic logarithmic slope for cancer induction was found to be about negative one-third for alpha-emitters or about negative two-thirds for beta-emitters. The relative biological effectiveness (RBE) of alpha versus beta radiations for cancer induction is a strong function of dose rate, near one at high dose rates and greater than 20 at low dose rates. The cumulative dose required to yield any level of induced-cancer risk is less at lower dose rates than at higher dose rates showing an apparent inverse-dose effect (up to a factor of 10 for high LET alpha radiation and a factor of 2 for low LET beta radiation). The competing risks of death associated with radiation injury, radiation-induced cancer, and natural aging are graphically shown using three-dimensional illustrations. At the higher average dose rates the principal deleterious effects are those associated with radiation-induced injury while at intermediate average dose rates radiation-induced cancer predominates. At the lower average dose rates the long latency time required for radiation-induced cancer may exceed natural life span, yielding an apparent lifespan effective threshold for death associated with radiation-induced cancer for cumulative doses to the target tissue below from 1.1 to

  19. What Makes International Capital Flows So Volatile?: Push vs. Pull Factors in the Case of Korea

    Directory of Open Access Journals (Sweden)

    Tae-Joon Kim

    2010-12-01

    Full Text Available This paper analyzes the determinants of financial capital flows in Korea, which provides an intriguing case for examining the volatility of such flows as an almost fully opened capital market. Our empirical analysis finds both pull and push factors have significantly affected all three types of foreign capital flows- foreign equity investment, foreign bond investment and foreign other-type investment- in Korea, though the relative importance of each factor varies by sample period and type of financial capital. First, the determinants of capital inflows changed substantially following the 1997 currency crisis. The impact of push factors on foreign investment strengthened, rendering the Korean stock and bond market more susceptible to external shocks. Second, the global financial crisis, which increased global financial instability and preference for safe assets, appears to have had a negative effect on other-type investment. However, fThis paper analyzes the determinants of financial capital flows in Korea, which provides an intriguing case for examining the volatility of such flows as an almost fully opened capital market. Our empirical analysis finds both pull and push factors have significantly affected all three types of foreign capital flows- foreign equity investment, foreign bond investment and foreign other-type investment- in Korea, though the relative importance of each factor varies by sample period and type of financial capital. First, the determinants of capital inflows changed substantially following the 1997 currency crisis. The impact of push factors on foreign investment strengthened, rendering the Korean stock and bond market more susceptible to external shocks. Second, the global financial crisis, which increased global financial instability and preference for safe assets, appears to have had a negative effect on other-type investment. However, foreign equity investment showed a quick recovery in the wake of global financial

  20. Effective diffusion in time-periodic linear planar flow

    International Nuclear Information System (INIS)

    Indeikina, A.; Chang, H.

    1993-01-01

    It is shown that when a point source of solute is inserted into a time-periodic, unbounded linear planar flow, the large-time, time-average transport of the solute can be described by classical anisotropic diffusion with constant effective diffusion tensors. For a given vorticity and forcing period, elongational flow is shown to be the most dispersive followed by simple shear and rotational flow. Large-time diffusivity along the major axis of the time-average concentration ellipse, whose alignment is predicted from the theory, is shown to increase with vorticity for all flows and decrease with increasing forcing frequency for elongational flow and simple shear. For the interesting case of rotational flow, there exist discrete resonant frequencies where the time-average major diffusivity reaches local maxima equal to the time-average steady flow case with zero forcing frequency

  1. Inertial Effects on Flow and Transport in Heterogeneous Porous Media.

    Science.gov (United States)

    Nissan, Alon; Berkowitz, Brian

    2018-02-02

    We investigate the effects of high fluid velocities on flow and tracer transport in heterogeneous porous media. We simulate fluid flow and advective transport through two-dimensional pore-scale matrices with varying structural complexity. As the Reynolds number increases, the flow regime transitions from linear to nonlinear; this behavior is controlled by the medium structure, where higher complexity amplifies inertial effects. The result is, nonintuitively, increased homogenization of the flow field, which leads in the context of conservative chemical transport to less anomalous behavior. We quantify the transport patterns via a continuous time random walk, using the spatial distribution of the kinetic energy within the fluid as a characteristic measure.

  2. Tip clearance effect on through-flow and performance of a centrifugal compressor

    International Nuclear Information System (INIS)

    Eum, Hark Jin; Kang, Young Seok; Kang, Shin Hyoung

    2004-01-01

    Numerical simulations have been performed to investigate tip clearance effect on through-flow and performance of a centrifugal compressor which has the same configuration of impeller with six different tip clearances. Secondary flow and loss distribution have been surveyed to understand the flow mechanism due to the tip clearance. Tip leakage flow strongly interacts with mainstream flow and considerably changes the secondary flow and the loss distribution inside the impeller passage. A method has been described to quantitatively estimate the tip clearance effect on the performance drop and the efficiency drop. The tip clearance has caused specific work reduction and additional entropy generation. The former, which is called inviscid loss, is independent of any internal loss and the latter, which is called viscous loss, is dependent on every loss in the flow passage. Two components equally affected the performance drop as the tip clearances were small, while the efficiency drop was influenced by the viscous component alone. The additional entropy generation was modeled with all the kinetic energy of the tip leakage flow. Therefore, the present paper can provide how to quantitatively estimate the tip clearance effect on the performance and efficiency

  3. First international symposium on Flow Induced Noise and Vibration Issues and Aspects

    CERN Document Server

    Rosa, Sergio; Franco, Francesco; Guyader, Jean-Louis; Hambric, Stephen; Flinovia - Flow Induced Noise and Vibration Issues and Aspects

    2015-01-01

    Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field. It describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation;
for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays;
for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements;
for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses. This book p...

  4. Spontaneous regression of two supraophthalmic internal cerebral artery aneurysms following flow pattern alteration

    International Nuclear Information System (INIS)

    Hans, F.J.; Reinges, M.H.T.; Krings, T.; Mull, M.

    2004-01-01

    We report on a patient with fibromuscular dysplasia who presented with a right-sided giant calcified cavernous internal carotid artery (ICA) aneurysm and two additional supraophthalmic ICA aneurysms. Endovascular closure of the right ICA using detachable balloons was performed with collateralisation of the right hemisphere via the right-sided posterior communicating and the anterior communicating arteries. Repeat angiography after 6 months demonstrated spontaneous complete regression of the two supraophthalmic aneurysms, although the parent vessel was still perfused. In comparison to the former angiography, the flow within the parent vessel was reversed due to the proximal ICA balloon occlusion. MRI demonstrated that the aneurysms were not obliterated by thrombosis alone, but showed a real regression in size. This case report demonstrates that changes in cerebral hemodynamics potentially lead to plastic changes in the vessel architecture in adults and that aneurysms can be flow-related, even if not associated with high flow fistulas or arteriovenous malformations, especially in cases with an arterial wall disease. (orig.)

  5. Linear Stability Analysis of Flow in an Internally Heated Rectangular Duct

    Energy Technology Data Exchange (ETDEWEB)

    Uhlmann, M.

    2004-07-01

    The linear stability of flow in a vertical rectangular duct subject to homogeneous internal heating, constant-temperature no-slip walls and a driving pressure gradient is investigated numerically. A full Chebyshevbased Galerkin method is found to be more reliable than a collocation method, both including the elimination of the pressure and the stream wise velocity from the system of equations and making use of the full symmetry properties. A classification of the mean flow-obtained as a function of Grashof and Reynolds numbers and the geometrical aspect ratio in terms of its inflectional properties is proposed. It is found that the flow loses stability at all aspects rations for a combination of finite thermal buoyancy and pressure forces with opposed sings. In the square duct, the unstable region coincides with the range where additional inflection lines are observed the mean velocity profile. Unstable eigenfunctions are obtained for all basic symmetry modes and their structure can be described as slightly elongated pockets of cross-stream-vertical motion, training each other along the stream wise direction. (Author) 22 refs.

  6. Performance Evaluation of the International Space Station Flow Boiling and Condensation Experiment (FBCE) Test Facility

    Science.gov (United States)

    Hasan, Mohammad; Balasubramaniam, R.; Nahra, Henry; Mackey, Jeff; Hall, Nancy; Frankenfield, Bruce; Harpster, George; May, Rochelle; Mudawar, Issam; Kharangate, Chirag R.; hide

    2016-01-01

    A ground-based experimental facility to perform flow boiling and condensation experiments is built in support of the development of the long duration Flow Boiling and Condensation Experiment (FBCE) destined for operation on board of the International Space Station (ISS) Fluid Integrated Rack (FIR). We performed tests with the condensation test module oriented horizontally and vertically. Using FC-72 as the test fluid and water as the cooling fluid, we evaluated the operational characteristics of the condensation module and generated ground based data encompassing the range of parameters of interest to the condensation experiment to be performed on the ISS. During this testing, we also evaluated the pressure drop profile across different components of the fluid subsystem, heater performance, on-orbit degassing subsystem, and the heat loss from different components. In this presentation, we discuss representative results of performance testing of the FBCE flow loop. These results will be used in the refinement of the flight system design and build-up of the FBCE which is scheduled for flight in 2019.

  7. Effects of external and gap mean flows on sound transmission through a double-wall sandwich panel

    Science.gov (United States)

    Liu, Yu; Sebastian, Alexis

    2015-05-01

    This paper studies analytically the effects of an external mean flow and an internal gap mean flow on sound transmission through a double-wall sandwich panel lined with poroelastic materials. Biot's theory is employed to describe wave propagation in poroelastic materials, and the transfer matrix method with three types of boundary conditions is applied to solve the system simultaneously. The random incidence transmission loss in a diffuse field is calculated numerically, and the limiting angle of incidence due to total internal reflection is discussed in detail. The numerical predictions suggest that the sound insulation performance of such a double-wall panel is enhanced considerably by both external and gap mean flows particularly in the high-frequency range. Similar effects on transmission loss are observed for the two mean flows. It is shown that the effect of the gap mean flow depends on flow velocity, flow direction, gap depth and fluid properties and also that the fluid properties within the gap appear to influence the transmission loss more effectively than the gap flow. Despite the implementation difficulty in practice, an internal gap flow provides more design space for tuning the sound insulation performance of a double-wall sandwich panel and has great potential for active/passive noise control.

  8. Fluid-elastic Instability of Helical Tubes Subjected to Single-Phase External Flow and Two-Phase Internal Flow

    International Nuclear Information System (INIS)

    Jong Chull Jo; Myung Jo Jhung; Woong Sik Kim; Hho Jung Kim

    2004-01-01

    This study investigates the fluid-elastic instability characteristics of steam generator helical type tubes in operating nuclear power plants. The thermal-hydraulic conditions of both tube side and shell side flow fields are predicted by a general purpose computational fluid dynamics code employing the finite volume element modeling. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for helical type tubes with various conditions. Investigated are the effects of the helix angle, the number of supports and the status of the inner fluid on the modal, and fluid-elastic instability characteristics of the tubes, which are expressed in terms of the natural frequency, corresponding mode shape, and stability ratio. (authors)

  9. Homotopy Perturbation Method for Thin Film Flow and Heat Transfer over an Unsteady Stretching Sheet with Internal Heating and Variable Heat Flux

    Directory of Open Access Journals (Sweden)

    I-Chung Liu

    2012-01-01

    Full Text Available We have analyzed the effects of variable heat flux and internal heat generation on the flow and heat transfer in a thin film on a horizontal sheet in the presence of thermal radiation. Similarity transformations are used to transform the governing equations to a set of coupled nonlinear ordinary differential equations. The obtained differential equations are solved approximately by the homotopy perturbation method (HPM. The effects of various parameters governing the flow and heat transfer in this study are discussed and presented graphically. Comparison of numerical results is made with the earlier published results under limiting cases.

  10. The Effect of Internal Leakages on Thermal Performance in NPPs

    International Nuclear Information System (INIS)

    Heo, Gyun Young; Kim, Doo Won; Jang, Seok Bo

    2007-01-01

    Since the Balance Of Plant (BOP, limited to a turbine cycle in this study) does not contain radioactive material, regulatory authorities did not need to have concerns on it. As the interests on safety and performance is getting more serious and extensive, controlling the level of safety and performance of a BOP have just begun or is about to begin. The performance standards or ageing management programs of the major equipment in a BOP is being developed. The regulatory requirements for tests and/or maintenance are being actively built up. There is also a probabilistic approach quantifying performance of a BOP. The study on quantifying the rate of unanticipated shutdowns caused by careless maintenance and/or tests conducted in a BOP is going on. In this study, the modeling of the entire BOP and the methodologies of thermal performance analysis should be one of the must-have items as well. This study was achieved to ensure fundamental skills related to 1) the detailed steady-state modeling of a BOP and 2) thermal performance analysis under various conditions. Particularly, the paper will focus on the effect of internal leakages inside the valves and FeedWater Heaters (FWHs). The internal leakage is regarded as the flow movement through the isolated path but remaining inside the system boundary of a BOP. For instance, the leakage from one side of a valve seat to the other side, or the leakage through the cracked tubes or tube-sheets in a heat exchanger correspond to internal leakages. We made a BOP model of OPR1000 and investigated thermal performance under the internal leakage in Turbine Bypass Condenser Dump Valves (TBCDV) and FWHs

  11. Numerical analysis of flow interaction of turbine system in two-stage turbocharger of internal combustion engine

    Science.gov (United States)

    Liu, Y. B.; Zhuge, W. L.; Zhang, Y. J.; Zhang, S. Y.

    2016-05-01

    To reach the goal of energy conservation and emission reduction, high intake pressure is needed to meet the demand of high power density and high EGR rate for internal combustion engine. Present power density of diesel engine has reached 90KW/L and intake pressure ratio needed is over 5. Two-stage turbocharging system is an effective way to realize high compression ratio. Because turbocharging system compression work derives from exhaust gas energy. Efficiency of exhaust gas energy influenced by design and matching of turbine system is important to performance of high supercharging engine. Conventional turbine system is assembled by single-stage turbocharger turbines and turbine matching is based on turbine MAP measured on test rig. Flow between turbine system is assumed uniform and value of outlet physical quantities of turbine are regarded as the same as ambient value. However, there are three-dimension flow field distortion and outlet physical quantities value change which will influence performance of turbine system as were demonstrated by some studies. For engine equipped with two-stage turbocharging system, optimization of turbine system design will increase efficiency of exhaust gas energy and thereby increase engine power density. However flow interaction of turbine system will change flow in turbine and influence turbine performance. To recognize the interaction characteristics between high pressure turbine and low pressure turbine, flow in turbine system is modeled and simulated numerically. The calculation results suggested that static pressure field at inlet to low pressure turbine increases back pressure of high pressure turbine, however efficiency of high pressure turbine changes little; distorted velocity field at outlet to high pressure turbine results in swirl at inlet to low pressure turbine. Clockwise swirl results in large negative angle of attack at inlet to rotor which causes flow loss in turbine impeller passages and decreases turbine

  12. International Migration and its Effects on Family

    Directory of Open Access Journals (Sweden)

    Cornel Constantinescu

    2008-03-01

    Full Text Available The crises period that still cross Romania explain, between others, the apparition and development of international migration, after 1990. In a world marked by globalization, migration can not disappear, contrary, it grows bigger ant it remains an interesting subject in future. A study about migration consequences on family, specially on children’s personality left in the country, is justified because migration is a present phenomena in Romanian space at the beginning of the XXIth century. We try to analyse the effects of this phenomenon on family. Related to these goal we offer the conclusions obtained from a research realized in Campulung Muscel municipality, Arges county, on a lot of pupils that have parents left in foreign countries and the results to the investigation made in Pitesti municipality. The research showed that it is a relationship between children’s marks at school and parent’s leaving; children’s perceptions on parent’s leaving; identifies school’s interest level in diminution of the low school performance effects caused by this socio-economical phenomena.

  13. An analysis of numerical convergence in discrete velocity gas dynamics for internal flows

    Science.gov (United States)

    Sekaran, Aarthi; Varghese, Philip; Goldstein, David

    2018-07-01

    The Discrete Velocity Method (DVM) for solving the Boltzmann equation has significant advantages in the modeling of non-equilibrium and near equilibrium flows as compared to other methods in terms of reduced statistical noise, faster solutions and the ability to handle transient flows. Yet the DVM performance for rarefied flow in complex, small-scale geometries, in microelectromechanical (MEMS) devices for instance, is yet to be studied in detail. The present study focuses on the performance of the DVM for locally large Knudsen number flows of argon around sharp corners and other sources for discontinuities in the distribution function. Our analysis details the nature of the solution for some benchmark cases and introduces the concept of solution convergence for the transport terms in the discrete velocity Boltzmann equation. The limiting effects of the velocity space discretization are also investigated and the constraints on obtaining a robust, consistent solution are derived. We propose techniques to maintain solution convergence and demonstrate the implementation of a specific strategy and its effect on the fidelity of the solution for some benchmark cases.

  14. Modifying intake flow to increase EGR tolerance in an Internal Combustion Engine

    Science.gov (United States)

    Rubio, Daniel; Drabo, Mebougna; Puzinauskas, Paul

    2010-11-01

    The worldwide effort to reduce vehicle emissions and increase fuel efficiencies has continuously intensified as the need to improve air quality and reduce fuel consumption becomes more acute. Exhaust gas recirculation (EGR) is a method that has long been employed to reduce combustion temperatures and therefore reduce thermal NOx formation and accommodate higher compression ratios and more optimum combustion phasing for improved efficiency. Generally the effective EGR level as a percent of trapped charge is limited by its affect on combustion stability. Inducing flow structures such as swirl, squish and tumble in the trapped charge have proven to extend this EGR limit in homogeneous charge spark-ignited engines at part load, but this enhancement has not been significantly studied at full loads in such engines. This research explored modifying the intake flow into an engine to create tumble and evaluate its effect at high loads in such engines. This exploration included characterizing the flow on a steady flow bench and quantifying the results using engine dynamometer tests.

  15. Effect of material flows on energy intensity in process industries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Liru; Aye, Lu [International Technologies Center (IDTC), Department of Civil and Environmental Engineering, The University of Melbourne, Victoria 3010 (Australia); Lu, Zhongwu [Institute of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Peihong [Department of Municipal and Environmental Engineering, Shenyang Architecture University, Shenyang 110168 (China)

    2006-09-15

    Many energy-intensive process industries have complex material flows, which have a strong effect on the overall energy intensity of the final product (OEIF). This problem, however, has only been recognised qualitatively due to the lack of quantitative analysis methods. This paper presents an in-depth quantitative analysis of the effect of material flows on energy intensity in process industries. Based on the concept of a standard material flow diagram (SMFD), as used in steel manufacturing, the SMFD for a generic process industry was first developed. Then material flow scenarios were addressed in a practical material flow diagram (PMFD) using the characteristics of practical process industries. The effect of each material flow deviating from a SMFD on the OEIF was analysed. The steps involved in analysing the effect of material flows in a PMFD on its energy intensity are also discussed in detail. Finally, using 1999 statistical data from the Chinese Zhenzhou alumina refinery plant, the PMFD and SMFD for this plant were constructed as a case study. The effect of material flows on the overall energy intensity of alumina (OEIA) was thus analysed quantitatively. To decrease OEIA, the process variations which decrease the product ratios could be employed in all except in multi-supplied fraction cases. In these cases, the fractions from the stream with lower energy intensities should be increased. (author)

  16. Effects of Core Cavity on a Flow Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Tae-Soon; Kim, Kihwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The axial pressure drop is removed in the free core condition, But the actual core has lots of fuel bundles and mixing vanes to the flow direction. The axial pressure drop induces flow uniformity. In a uniform flow having no shear stress, the cross flow or cross flow mixing decreases. The mixing factor is important in the reactor safety during a Steam Line Break (SLB) or Main Steam Line Break (MSLB) transients. And the effect of core cavity is needed to evaluate the realistic core mixing factor quantification. The multi-dimensional flow mixing phenomena in a core cavity has been studied using a CFD code. The 1/5-scale model was applied for the reactor flow analysis. A single phase water flow conditions were considered for the 4-cold leg and DVI flows. To quantify the mixing intensity, a boron scalar was introduced to the ECC injection water at cold legs and DVI nozzles. The present CFD pre-study was performed to quantify the effects of core structure on the mixing phenomena. The quantified boron mixing scalar in the core simulator model represented the effect of core cavity on the core mixing phenomena. This simulation results also give the information for sensor resolution to measure the boron concentration in the experiments and response time to detect mixing phenomena at the core and reactor vessel.

  17. Determinants of Effective Internal Control System in Nigerian Banks ...

    African Journals Online (AJOL)

    Determinants of Effective Internal Control System in Nigerian Banks. ... (21) chief internal auditors of selected recapitalized banks currently operating in Port Harcourt. ... can be carried out, high level ethical standards should be enshrined in Nigerian banks to make internal control more effective. ... HOW TO USE AJOL.

  18. Effect of Internal and Edge Transport Barriers in ITER Simulations

    International Nuclear Information System (INIS)

    Pianroj, Y.; Onjun, T.; Suwanna, S.; Picha, R.; Poolyarat, N.

    2009-07-01

    Full text: Predictive simulations of ITER with the presence of both an edge transport barrier (ETB) and an internal transport barrier (ITB) are carried out using the BALDUR integrated predictive modeling code. In these simulations, the boundary is taken at the top of the pedestal, where the pedestal values are described using the theory-based pedestal models. These pedestal temperature models are based on three different pedestal width scalings: magnetic and flow shear stabilization (δ α ρ ζ 2 ), flow shear stabilization (δ α Root ρ Rq), and normalized poloidal pressure (δ α R Root βθ, ped). The pedestal width scalings are combined with a pedestal pressure gradient scaling based on ballooning mode limit to predict the pedestal temperature. A version of the semi-empirical Mixed Bohm/gyro Bohm (Mixed B/gB) core transport model that includes ITB effects is used to compute the evolution of plasma profiles and plasma performance, which defined by Fusion Q factor. The results from the cases excluding and including ITB are compared. The preliminary results show the Q value resulted from ITB-excluded simulation is less than the one with ITB included

  19. Torsion effect on fully developed flow in a helical pipe

    Science.gov (United States)

    Kao, Hsiao C.

    1987-01-01

    Two techniques, a series expansion method of perturbed Poiseuille flow valid for low Dean numbers and a solution of the complete Navier-Stokes equation applicable to intermediate Dean values, are used to investigate the torsion effect on the fully developed laminar flow in a helical pipe of constant circular cross section. For the secondary flow patterns, the results show that the presence of torsion can produce a significant effect if the ratio of the curvature to the torsion is of order unity. The secondary flow is distorted in these cases. It is noted that the torsion effect is, however, usually small, and that the secondary flow has the usual pattern of a pair of counter-rotating vortices of nearly equal strength.

  20. Internal Flow Structures in Columnar Jointed Basalt from HREPPHÓLAR, Iceland

    Science.gov (United States)

    Mattsson, H. B.; Bosshard, S. A.; Hetenyi, G.; Almqvist, B.; Hirt, A. M.; Caricchi, L.; Caddick, M.

    2010-12-01

    Columnar jointed basalt from Hrepphólar in southern Iceland display spectacular internal structures when cut. These structures follow the overall orientation of the columns and display semi-circular to circular features when cross-cut. It was previously believed that these internal structures formed as a result of alteration due to circulation of meteoric water within the column-bounding fractures after emplacement. However, new field observations of viscous fingering within the columns and the fact that approximately 80% of the semi-circular features are found within the column whereas the remaining 20% are cut by the column-bounding fractures clearly shows that these internal structures must have formed prior to crack-propagation (and are thus primary features). Here we present the results of textural and petrological analyses through a cross-section of a column, in combination with magnetic susceptibility and anisotropy measurements of the same samples. The variation in textures and geochemistry can be attributed to the presence of diffuse banding caused by variations in the modal proportions of the main phenocryst phases (i.e., plagioclase, clinopyroxene, olivine and titanomagnetite/ilmenite). Orientation of plagioclase laths and titanomagnetite crystals (based on measurements in thin sections and AMS-measurements) are consistent with vertical flow alignment. Nowhere in the column can evidence for downwards flow be found (excluding the possibility of small-scale convection cells generating these features). It is proposed here, that the volume decrease associated with solidification (typically 10-15 vol.% for basaltic systems) and the increasing weight of the overlying crust results in upwelling of partially crystallized material into the centre of the columns. Preliminary numerical modeling indicates that the isotherms within individual columns become steeper with increasing depth in a lava flow (allowing for larger displacement distances). We propose that

  1. Acute effects of hemodialysis on salivary flow rate and composition

    NARCIS (Netherlands)

    Bots, C. P.; Brand, H. S.; Veerman, E. C. I.; Valentijn-Benz, M.; Henskens, Y. M. C.; Valentijn, R. M.; Vos, P. F.; Bijlsma, J. A.; ter Wee, P. M.; van Amerongen, B. M.; Nieuw Amerongen, A. V.

    2007-01-01

    To evaluate acute effects of hemodialysis (HD) on the salivary flow rate, pH and biochemical composition before, during and after completion of a dialysis session. Unstimulated whole saliva (UWS) and chewing-stimulated whole saliva (CH-SWS) were collected in 94 HD patients. Salivary flow rate, pH,

  2. Linking flow, water quality and potential effects on aquatic biota ...

    African Journals Online (AJOL)

    Linking the potential effects of altered water quality on aquatic biota, that may result from a change in the flow (discharge) regime, is an essential step in the maintenance of riverine ecological functioning. Determination of the environmental flow requirement of a river (as well as other activities, such as classifying the ...

  3. Geometrical effects on the airfoil flow separation and transition

    KAUST Repository

    Zhang, Wei; Cheng, Wan; Gao, Wei; Qamar, Adnan; Samtaney, Ravi

    2015-01-01

    We present results from direct numerical simulations (DNS) of incompressible flow over two airfoils, NACA-4412 and NACA-0012-64, to investigate the effects of the airfoil geometry on the flow separation and transition patterns at Re=104 and 10

  4. Effect of fluocinolone acetonide cream on human skin blood flow

    International Nuclear Information System (INIS)

    Chimoskey, J.E.; Holloway, A. Jr.; Flanagan, W.J.

    1975-01-01

    Blood flow rate was measured in the forearm skin of human subjects exposed to ultraviolet irradiation. Blood flow was determined by the 133 Xe disappearance technique 18 hr after ultraviolet (UV) irradiation with a Westinghouse RS sunlamp held 10 inches from the skin for 10 min. Ultraviolet irradiation caused skin blood flow to increase. Application of fluocinolone acetonide cream, 0.025 percent, 4 times in the 16 hr following UV irradiation had no effect on either control skin blood flow or the UV-induced hyperemia

  5. Side Flow Effect on Surface Generation in Nano Cutting.

    Science.gov (United States)

    Xu, Feifei; Fang, Fengzhou; Zhang, Xiaodong

    2017-12-01

    The side flow of material in nano cutting is one of the most important factors that deteriorate the machined surface quality. The effects of the crystallographic orientation, feed, and the cutting tool geometry, including tool edge radius, rake angle and inclination angle, on the side flow are investigated employing molecular dynamics simulation. The results show that the stagnation region is formed in front of tool edge and it is characterized by the stagnation radius R s and stagnation height h s . The side flow is formed because the material at or under the stagnation region is extruded by the tool edge to flow to the side of the tool edge. Higher stagnation height would increase the size of the side flow. The anisotropic nature of the material which partly determines the stagnation region also influences the side flow due to the different deformation mechanism under the action of the tool edge. At different cutting directions, the size of the side flow has a great difference which would finally affect the machined surface quality. The cutting directions of {100} , {110} , and {110}  are beneficial to obtain a better surface quality with small side flow. Besides that, the side flow could be suppressed by reducing the feed and optimizing the cutting tool geometry. Cutting tool with small edge radius, large positive rake angle, and inclination angle would decrease the side flow and consequently improve the machined surface quality.

  6. Performance improvement of a cross-flow hydro turbine by air layer effect

    International Nuclear Information System (INIS)

    Choi, Y D; Yoon, H Y; Inagaki, M; Ooike, S; Kim, Y J; Lee, Y H

    2010-01-01

    The purpose of this study is not only to investigate the effects of air layer in the turbine chamber on the performance and internal flow of the cross-flow turbine, but also to suggest a newly developed air supply method. Field test is performed in order to measure the output power of the turbine by a new air supply method. CFD analysis on the performance and internal flow of the turbine is conducted by an unsteady state calculation using a two-phase flow model in order to embody the air layer effect on the turbine performance effectively.The result shows that air layer effect on the performance of the turbine is considerable. The air layer located in the turbine runner passage plays the role of preventing a shock loss at the runner axis and suppressing a recirculation flow in the runner. The location of air suction hole on the chamber wall is very important factor for the performance improvement. Moreover, the ratio between air from suction pipe and water from turbine inlet is also significant factor of the turbine performance.

  7. Teaching Effective Problem Solving Strategies for Interns

    Science.gov (United States)

    Warren, Louis L.

    2005-01-01

    This qualitative study investigates what problem solving strategies interns learn from their clinical teachers during their internships. Twenty-four interns who completed their internship in the elementary grades shared what problem solving strategies had the greatest impact upon them in learning how to deal with problems during their internship.…

  8. A STUDY ON THE INTERNAL MIGRATION FLOWS IN TURKEY: LOWRY HYPOTHESIS

    Directory of Open Access Journals (Sweden)

    FERHAT TOPBAŞ

    2013-06-01

    Full Text Available The purpose of this study is to re-examine Lowry hypothesis that were examined for Turkey in period of 1965–1980 by Gedik (1992 and period of 1985–1990 by Yamak and Küçükkale (2001 by using The Census of Population 1975, 1980, 1985, 1990 and 2000 in Turkey. For this reason, the relationships between in-migration and out-migration and net migration have investigated with population size, net migration rate and per capita income factors. Analysis that involve in all provinces called general model is not considered in social, economic and urban development factors. In addition, estimated restriction models that are considered urban development are involved population, net migration rate and per capita income factors. In conclusion we have exposed comparatively relationship between internal migration flows and urban development frame of estimated models.

  9. INTERNATIONAL LOGISTICS SYSTEMS DESIGN AND EFFECTIVENESS EVALUATION

    Directory of Open Access Journals (Sweden)

    N. V. Khalipova

    2015-08-01

    Full Text Available Purpose. In the paper the question of the development of a methodological approach to the determination of logistics systems’ performance and grounding of the most effective goods’ delivery schemes, based on the theory of functions and sets of multiple objects, vector optimization approaches and discrete maximum principle for multi-stage processes (phase method is considered. Methodology. To achieve the goals of the research, the model of logistic system represented by multiple object that defined by the structure and content. The object is represented by hybrid superposition, composed of sets, multi-sets, ordered sets (lists and inhomogeneous sets (sequences, corteges, which at each stage of cargo delivery present sets of technological operations of their processing, choices and decisions algorithms. Multiple structure of objects is constructive three, consisting of the carrier, signatures and axiomatic. To determine the effective scheme of delivery, applied discrete maximum principle using vector optimization criterion. Findings. In this article, logistics system of delivery is presented in the form of a multi-stage (phase of the process. Each stage reviews a plurality of discrete activities sets, which includes the possible technology cycles of operations in goods handling. At each stage of a multi-phase delivery process from the supplier to the consumer, these sets are different. Considered a model example solving the problem of vector optimization options for delivery of goods by the road in the international logistics system for the five-step process. Optimization performed on the basis of three indicators. Originality. In this paper, the choice of the most effective way of delivery goods produced using the theory of functions and sets of multiple objects, using the discrete maximum principle for multi-stage processes, based on the vector optimization criterion. At each of its stages are formed a plurality of valid solutions as

  10. Predicting bifurcation angle effect on blood flow in the microvasculature.

    Science.gov (United States)

    Yang, Jiho; Pak, Y Eugene; Lee, Tae-Rin

    2016-11-01

    Since blood viscosity is a basic parameter for understanding hemodynamics in human physiology, great amount of research has been done in order to accurately predict this highly non-Newtonian flow property. However, previous works lacked in consideration of hemodynamic changes induced by heterogeneous vessel networks. In this paper, the effect of bifurcation on hemodynamics in a microvasculature is quantitatively predicted. The flow resistance in a single bifurcation microvessel was calculated by combining a new simple mathematical model with 3-dimensional flow simulation for varying bifurcation angles under physiological flow conditions. Interestingly, the results indicate that flow resistance induced by vessel bifurcation holds a constant value of approximately 0.44 over the whole single bifurcation model below diameter of 60μm regardless of geometric parameters including bifurcation angle. Flow solutions computed from this new model showed substantial decrement in flow velocity relative to other mathematical models, which do not include vessel bifurcation effects, while pressure remained the same. Furthermore, when applying the bifurcation angle effect to the entire microvascular network, the simulation results gave better agreements with recent in vivo experimental measurements. This finding suggests a new paradigm in microvascular blood flow properties, that vessel bifurcation itself, regardless of its angle, holds considerable influence on blood viscosity, and this phenomenon will help to develop new predictive tools in microvascular research. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Characterizing copper flows in international trade of China, 1975-2015.

    Science.gov (United States)

    Zhang, Ling; Chen, Tianming; Yang, Jiameng; Cai, Zhijian; Sheng, Hu; Yuan, Zengwei; Wu, Huijun

    2017-12-01

    Since the economic reform, China has actively participated in the global market with rapid industrialization and gradually dominated the utilization and consumption of some critical materials, one of which is copper. China has reigned the global anthropogenic cycle of copper since 2004. We explore copper flows along with the international trade of China during 1975-2015, through life cycle lens, from ore to final products. Our main finding is that China has become more active in the copper-related trade, indicated by its great increase in trade volume and the number of trade partners. The physical volume of copper flows through trade increased over 119 times between 1975 and 2015, mainly because of more imported raw materials of copper and exported copper products. Generally, China is a net importer of copper, with increasing import dependence through the study period, whereas the degree of dependence slightly decreased from 2010 to 2015. The indicator of Export Support Rate took a decreasing percentage, which has fallen about 35% since 2010. It suggests China's changing position in the global resource and manufacturing market. In terms of trade price of different copper products, the price of imported copper concentrate was noticeably higher than that of exported one, revealing the poor copper resource endowment of China; while the different trend of copper semis in recent years signifies that China is in urgent need to improve its capability of producing high value-added semis. From international trade perspective, the copper resource of China presented stable supply as well as demand. The One Belt One Road strategy proposed by the state will further expand both the resource and market of copper. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Richardson effects in turbulent buoyant flows

    Science.gov (United States)

    Biggi, Renaud; Blanquart, Guillaume

    2010-11-01

    Rayleigh Taylor instabilities are found in a wide range of scientific fields from supernova explosions to underwater hot plumes. The turbulent flow is affected by the presence of buoyancy forces and may not follow the Kolmogorov theory anymore. The objective of the present work is to analyze the complex interactions between turbulence and buoyancy. Towards that goal, simulations have been performed with a high order, conservative, low Mach number code [Desjardins et. al. JCP 2010]. The configuration corresponds to a cubic box initially filled with homogeneous isotropic turbulence with heavy fluid on top and light gas at the bottom. The initial turbulent field was forced using linear forcing up to a Reynolds number of Reλ=55 [Meneveau & Rosales, POF 2005]. The Richardson number based on the rms velocity and the integral length scale was varied from 0.1 to 10 to investigate cases with weak and strong buoyancy. Cases with gravity as a stabilizer of turbulence (gravity pointing up) were also considered. The evolution of the turbulent kinetic energy and the total kinetic energy was analyzed and a simple phenomenological model was proposed. Finally, the energy spectra and the isotropy of the flow were also investigated.

  13. Proceedings of the 8. international conference on Flow-induced vibration

    International Nuclear Information System (INIS)

    Langre, E. de; Axisa, F.

    2004-01-01

    FIV2004, the eighth of the series of International Conferences on Flow-Induced Vibration initiated at Keswick in 1973, evidences the sustained interest of the scientific and engineering international community for a subject area which incorporates at least two major disciplines: fluid mechanics and structural dynamics. Flow induced vibration (FIV) occur whenever a structure is in contact with a flowing fluid; which is a very common occurrence indeed. FIV can be rightly perceived as very useful and agreeable, in musical instruments, or at the opposite as annoying and even disastrous, in mechanical engineering. In both cases, the subject motivates a large and highly diversified amount of research work, driven either by scientific curiosity or engineering concerns, or both. In this field, empirical knowledge and experience are a precious asset but a certain breadth of perspective gained through a thorough background in theoretical mechanics is also necessary. In other words, to deal successfully with FIV problems, theoretical and pragmatic knowledge must be skillfully interwoven. Having also in mind the impressive progress achieved since the early seventies both in experimental techniques and computer science, it is rather fascinating to realize that we have still to learn so much about so 'elementary' systems as a pipe conveying air or water, or cylindrical rods subjected to cross-flow, to mention just two archetypical systems which are in fact extremely complex and which motivated so many studies already at the time of the first Keswick Conference and which still do at FIV2004. Though such systems are encountered in many industrial components and are rather easily accessible to experiment, they still give rise to many challenging questions concerning the extremely varied dynamical behavior they can display, which remain often insufficiently amenable to prediction. By no means this is to say that the research work devoted to FIV up to now has been made in vain. First

  14. Effects of ship motions on laminar flow in tubes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, B.H., E-mail: yanbh1986@163.co [Department of Nuclear Science and Engineering, Naval University of Engineering, 717 Jiefang Street, Wuhan 430033 (China); Yu, L. [Department of Nuclear Science and Engineering, Naval University of Engineering, 717 Jiefang Street, Wuhan 430033 (China); Yang, Y.H. [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

    2010-01-15

    The thermal-hydraulics of barge-mounted floating nuclear desalination plants is the incentive for this study. Laminar flow in tubes in heaving motion is modeled. The friction factor and heat transfer coefficient are obtained. All the equations of laminar flow in steady state are applicable for heeling motion. The effect of ship motions on the laminar developing region is also analyzed. The ship motions can weaken the boundary layer in the laminar developing region and strengthen the laminar frictional resistance. The effect of ship motions on the instability of laminar flow is also investigated. The ship motions do not affect the instability point, but they can shorten the distance between the instability point and the transition point, and cause the transition from laminar flow to turbulent flow to occur earlier.

  15. The physical dimension of international trade. Part 1. Direct global flows between 1962 and 2005

    International Nuclear Information System (INIS)

    Dittrich, Monika; Bringezu, Stefan

    2010-01-01

    The physical dimension of international trade is attaining increased importance. This article describes a method to calculate complete physical trade flows for all countries which report their trade to the UN. The method is based on the UN Comtrade database and it was used to calculate world-wide physical trade flows for all reporting countries in nine selected years between 1962 and 2005. The results show increasing global trade with global direct material trade flows reaching about 10 billion tonnes in 2005, corresponding to a physical trade volume of about 20 billion tonnes (adding both total imports and total exports). The share from European countries is declining, mainly in favour of Asian countries. The dominant traded commodity in physical units was fossil fuels, mainly oil. Physical trade balances were used to identify the dominant resource suppliers and demanders. Australia was the principal resource supplier over the period with a diverse material export structure. It was followed by mainly oil-exporting countries with varying volumes. As regards to regions, Latin America, south-east Asian islands and central Asia were big resource exporters, mostly with increasing absolute amounts of net exports. The largest net importers were Japan, the United States and single European countries. Emerging countries like the 'Asian Tigers' with major industrial productive sectors are growing net importers, some of them to an even higher degree than European countries. Altogether, with the major exception of Australia and Canada, industrialized countries are net importers and developing countries and transition countries are net exporters, but there are important differences within these groups. (author)

  16. Virtual water flows in the international trade of agricultural products of China.

    Science.gov (United States)

    Zhang, Yu; Zhang, Jinhe; Tang, Guorong; Chen, Min; Wang, Lachun

    2016-07-01

    With the rapid development of the economy and population, water scarcity and poor water quality caused by water pollution have become increasingly severe in China. Virtual water trade is a useful tool to alleviate water shortage. This paper focuses on a comprehensive study of China's international virtual water flows from agricultural products trade and completes a diachronic analysis from 2001 to 2013. The results show that China was in trade surplus in relation to the virtual water trade of agricultural products. The exported virtual water amounted to 29.94billionm(3)/yr. while 155.55billionm(3)/yr. was embedded in imported products. The trend that China exported virtual water per year was on the decline while the imported was on a rising trend. Virtual water trade of China was highly concentrated. Not all of the exported products had comparative advantages in virtual water content. Imported products were excessively concentrated on water intensive agricultural products such as soya beans, cotton, and palm oil. The exported virtual water mainly flowed to the Republic of Korea, Hong Kong of China and Japan, while the imported mainly flowed from the United States of America, Brazil and Argentina. From the ethical point of view, the trade partners were classified into four types in terms of "net import" and "water abundance": mutual benefit countries, such as Australia and Canada; unilateral benefit countries, such as Mongolia and Norway; supported countries, such as Egypt and Singapore; and double pressure countries, such as India and Pakistan. Virtual water strategy refers to water resources, agricultural products and human beings. The findings are beneficial for innovating water resources management system, adjusting trade structure, ensuring food security in China, and promoting the construction of national ecological security system. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. CVB: the Constrained Vapor Bubble Capillary Experiment on the International Space Station MARANGONI FLOW REGION

    Science.gov (United States)

    Wayner, Peter C., Jr.; Kundan, Akshay; Plawsky, Joel

    2014-01-01

    The Constrained Vapor Bubble (CVB) is a wickless, grooved heat pipe and we report on a full- scale fluids experiment flown on the International Space Station (ISS). The CVB system consists of a relatively simple setup a quartz cuvette with sharp corners partially filled with either pentane or an ideal mixture of pentane and isohexane as the working fluids. Along with temperature and pressure measurements, the two-dimensional thickness profile of the menisci formed at the corners of the quartz cuvette was determined using the Light Microscopy Module (LMM). Even with the large, millimeter dimensions of the CVB, interfacial forces dominate in these exceedingly small Bond Number systems. The experiments were carried out at various power inputs. Although conceptually simple, the transport processes were found to be very complex with many different regions. At the heated end of the CVB, due to a high temperature gradient, we observed Marangoni flow at some power inputs. This region from the heated end to the central drop region is defined as a Marangoni dominated region. We present a simple analysis based on interfacial phenomena using only measurements from the ISS experiments that lead to a predictive equation for the thickness of the film near the heated end of the CVB. The average pressure gradient for flow in the film is assumed due to the measured capillary pressure at the two ends of the liquid film and that the pressure stress gradient due to cohesion self adjusts to a constant value over a distance L. The boundary conditions are the no slip condition at the wall interface and an interfacial shear stress at the liquid- vapor interface due to the Marangoni stress, which is due to the high temperature gradient. Although the heated end is extremely complex, since it includes three- dimensional variations in radiation, conduction, evaporation, condensation, fluid flow and interfacial forces, we find that using the above simplifying assumptions, a simple successful

  18. The Capillary Flow Experiments Aboard the International Space Station: Increments 9-15

    Science.gov (United States)

    Jenson, Ryan M.; Weislogel, Mark M.; Tavan, Noel T.; Chen, Yongkang; Semerjian, Ben; Bunnell, Charles T.; Collicott, Steven H.; Klatte, Jorg; dreyer, Michael E.

    2009-01-01

    This report provides a summary of the experimental, analytical, and numerical results of the Capillary Flow Experiment (CFE) performed aboard the International Space Station (ISS). The experiments were conducted in space beginning with Increment 9 through Increment 16, beginning August 2004 and ending December 2007. Both primary and extra science experiments were conducted during 19 operations performed by 7 astronauts including: M. Fincke, W. McArthur, J. Williams, S. Williams, M. Lopez-Alegria, C. Anderson, and P. Whitson. CFE consists of 6 approximately 1 to 2 kg handheld experiment units designed to investigate a selection of capillary phenomena of fundamental and applied importance, such as large length scale contact line dynamics (CFE-Contact Line), critical wetting in discontinuous structures (CFE-Vane Gap), and capillary flows and passive phase separations in complex containers (CFE-Interior Corner Flow). Highly quantitative video from the simply performed flight experiments provide data helpful in benchmarking numerical methods, confirming theoretical models, and guiding new model development. In an extensive executive summary, a brief history of the experiment is reviewed before introducing the science investigated. A selection of experimental results and comparisons with both analytic and numerical predictions is given. The subsequent chapters provide additional details of the experimental and analytical methods developed and employed. These include current presentations of the state of the data reduction which we anticipate will continue throughout the year and culminate in several more publications. An extensive appendix is used to provide support material such as an experiment history, dissemination items to date (CFE publication, etc.), detailed design drawings, and crew procedures. Despite the simple nature of the experiments and procedures, many of the experimental results may be practically employed to enhance the design of spacecraft engineering

  19. Electrokinetic Flow in Microchannels with Finite Reservoir Size Effects

    International Nuclear Information System (INIS)

    Yan, D; Yang, C; Nguyen, N-T; Huang, X

    2006-01-01

    In electrokinetically-driven microfluidic applications, reservoirs are indispensable and have finite sizes. During operation processes, as the liquid level difference in reservoirs keeps changing as time elapses, the flow characteristics in a microchannel exhibit a combination of the electroosmotic flow and the time-dependent induced backpressure-driven flow. In this work, an assessment of the finite reservoir size effect on electroosmotic flows is presented theoretically and experimentally. A model is developed to describe the timedependent electrokinetic flow with finite reservoir size effects. The theoretical analysis shows that under certain conditions the finite reservoir size effect is significant. The important parameters that describe the effect of finite reservoir size on the flow characteristics are discussed. A new concept denoted as 'effective pumping period' is introduced to characterize the reservoir size effect. The proposed model clearly identifies the mechanisms of the finitereservoir size effects and is further confirmed by using micro-PIV technique. The results of this study can be used for facilitating the design of microfluidic devices

  20. The effect of topography on pyroclastic flow mobility

    Science.gov (United States)

    Ogburn, S. E.; Calder, E. S.

    2010-12-01

    Pyroclastic flows are among the most destructive volcanic phenomena. Hazard mitigation depends upon accurate forecasting of possible flow paths, often using computational models. Two main metrics have been proposed to describe the mobility of pyroclastic flows. The Heim coefficient, height-dropped/run-out (H/L), exhibits an inverse relationship with flow volume. This coefficient corresponds to the coefficient of friction and informs computational models that use Coulomb friction laws. Another mobility measure states that with constant shear stress, planimetric area is proportional to the flow volume raised to the 2/3 power (A∝V^(2/3)). This relationship is incorporated in models using constant shear stress instead of constant friction, and used directly by some empirical models. Pyroclastic flows from Soufriere Hills Volcano, Montserrat; Unzen, Japan; Colima, Mexico; and Augustine, Alaska are well described by these metrics. However, flows in specific valleys exhibit differences in mobility. This study investigates the effect of topography on pyroclastic flow mobility, as measured by the above mentioned mobility metrics. Valley width, depth, and cross-sectional area all influence flow mobility. Investigating the appropriateness of these mobility measures, as well as the computational models they inform, indicates certain circumstances under which each model performs optimally. Knowing which conditions call for which models allows for better model selection or model weighting, and therefore, more realistic hazard predictions.

  1. Embodied carbon dioxide flow in international trade: A comparative analysis based on China and Japan.

    Science.gov (United States)

    Long, Ruyin; Li, Jinqiu; Chen, Hong; Zhang, Linling; Li, Qianwen

    2018-03-01

    Carbon dioxide embodied flow in international trade has become an important factor in defining global carbon emission responsibility and climate policy. We conducted an empirical analysis for China and Japan for the years 2000-2014, using a multi-region input-output model and considering the rest of the world as a comparison group. We compared the two countries' direct and complete carbon dioxide emissions intensity and bilateral economic activities such as imports and exports, production and consumption to analyze the difference between China and Japan. The results showed that the intensities of carbon emissions in all sectors of China were higher than that in Japan and that China's annual production-based emissions were greater than consumption-based emissions, the opposite of these relationships in Japan. China was a typical net carbon export country, and carbon embodied in its imports and exports continued to increase throughout the study period. In contrast, Japan's volume and growth rate of embodied carbon emissions were far less than China's and Japan was a typical net carbon import country. Finally, the conclusions of this study support recommendations for the formulation of international carbon emission responsibility allocation, domestic abatement policy as well as China's trade policy. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. The stably stratified internal boundary layer for steady and diurnally varying offshore flow

    Science.gov (United States)

    Garratt, J. R.

    1987-03-01

    A two-dimensional numerical mesoscale model is used to investigate the internal structure and growth of the stably stratified internal boundary layer (IBL) beneath warm, continental air flowing over a cooler sea. Two situations are studied — steady-state and diurnally varying offshore flow. In the steady-state case, vertical profiles of mean quantities and eddy diffusion coefficients ( K) within the IBL show small, but significant, changes with increasing distance from the coast. The top of the IBL is well defined, with large vertical gradients within the layer and a maximum in the coast-normal wind component near the top. Well away from the coast, turbulence, identified by non-zero K, decreases to insignificant levels near the top of the IBL; the IBL itself is characterised by a critical value of the layer-flux Richardson number equal to 0.18. The overall behaviour of the mean profiles is similar to that found in the horizontally homogeneous stable boundary layer over land. A simple physical model is used to relate the depth of the layer h to several relevant physical parameters viz., x, the distance from the coast and U, the large-scale wind (both normal to the coastline) and gδθ/θ, Δθ being the temperature difference between continental mixed-layer air and sea surface, θ is the mean potential temperature and g is the acceleration due to gravity. Excellent agreement with the numerical results is found, with h = 0.014 x 1/2 U ( gδθ/θ)-1/2. In the diurnally varying case, the mean profiles within the IBL show only small differences from the steady-state case, although diurnal variations, particularly in the wind maximum, are evident within a few hundred kilometres of the coast. A mesoscale circulation normal to the coast, and superimposed upon the mean offshore flow, develops seawards of the coastline with maximum vertical velocities about sunset, of depth about 2 km and horizontal scale ≈ 500 km. The circulation is related to the advection, and

  3. Anthropogenic effect on avalanche and debris flow activity

    Directory of Open Access Journals (Sweden)

    S. A. Sokratov

    2013-01-01

    Full Text Available The paper presents examples of the change in snow avalanches and debris flows activity due to the anthropogenic pressure on vegetation and relief. The changes in dynamical characteristics of selected snow avalanches and debris flows due to the anthropogenic activity are quantified. The conclusion is made that the anthropogenic effects on the snow avalanches and debris flows activity are more pronounced than the possible effects of the climate change. The necessity is expressed on the unavoidable changes of the natural environment as the result of a construction and of use of the constructed infrastructure to be account for in corresponding planning of the protection measures.

  4. Numerical studies of transverse curvature effects on transonic flow stability

    Science.gov (United States)

    Macaraeg, M. G.; Daudpota, Q. I.

    1992-01-01

    A numerical study of transverse curvature effects on compressible flow temporal stability for transonic to low supersonic Mach numbers is presented for axisymmetric modes. The mean flows studied include a similar boundary-layer profile and a nonsimilar axisymmetric boundary-layer solution. The effect of neglecting curvature in the mean flow produces only small quantitative changes in the disturbance growth rate. For transonic Mach numbers (1-1.4) and aerodynamically relevant Reynolds numbers (5000-10,000 based on displacement thickness), the maximum growth rate is found to increase with curvature - the maximum occurring at a nondimensional radius (based on displacement thickness) between 30 and 100.

  5. Effect of polymer additives on transition in pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Castro, W; Squire, W

    1967-09-01

    Small amounts of long-chain, water-soluble polymers have a marked effect on turbulent flow resulting in appreciable reduction of turbulent friction. The maximum reduction in pipe flow resistance is obtained at such low concentrations that the density and viscosity are not altered appreciably. The minimum friction curve varies as Re-2/3 and appears to be the same for all effective additives tested. The transition process is affected by these additives. Quantitative results are presented showing a reduction in the intensity of the turbulent flashes and the fraction of the time the flow is turbulent at a given Reynolds number. (13 refs.)

  6. Analysis of transit time flow of the right internal thoracic artery anastomosed to the left anterior descending artery compared to the left internal thoracic artery

    Science.gov (United States)

    Milani, Rodrigo; de Moraes, Daniela; Sanches, Aline; Jardim, Rodrigo; Lumikoski, Thais; Miotto, Gabriela; Santana, Vitor Hugo; Brofman, Paulo Roberto

    2014-01-01

    Introduction We evaluated with transit time flow the performance of the right and left thoracic arteries when used as a graft for the left anterior descending artery. Methods Fifty patients undergoing surgery for myocardial revascularization without cardiopulmonary bypass were divided into two groups. In group A patients received graft of right internal mammary artery to the anterior interventricular branch. In group B patients received graft of left internal mammary artery to the same branch. At the end of the operation the flow was assessed by measuring transit time. Results In group A, mean age was 60.6±9.49 years. The average height and weight of the group was 80.4±10.32 kg and 169.2±6.86 cm. The average number of grafts per patient in this group was 3.28±1.49. The mean flow and distal resistance obtained in right internal thoracic artery was 42.1±23.4 ml/min and 2.8±0.9 respectively. In group B, the mean age was 59.8±9.7 years. The average height and weight of this group was 77.7±14.22 kg and 166.0±8.2 cm. The average number of grafts per patient in this group was 3.08 ±0.82. The mean flow and distal resistance observed in this group was 34.2±19.1 ml/min and 2.0±0.7. There were no deaths in this series. Conclusion Right internal mammary artery presented a similar behavior to left internal mammary artery when anastomosed to the anterior interventricular branch of the left coronary artery. There was no statistical difference between the measured flow obtained between both arteries. PMID:25140463

  7. EFFECT OF ION ∇ B DRIFT DIRECTION ON TURBULENCE FLOW AND FLOW SHEAR

    International Nuclear Information System (INIS)

    FENZI, C; McKEE, G.R; BURRELL, K.H; CARLSTROM, T.N; FONCK, R.J; GROEBNER, R.J

    2003-01-01

    The divertor magnetic geometry has a significant effect on the poloidal flow and resulting flow shear of turbulence in the outer region of L-mode tokamak plasmas, as determined via two-dimensional measurements of density fluctuations with Beam Emission Spectroscopy on DIII-D. Plasmas with similar parameters, except that in one case the ion (del)B drift points towards the divertor X-point (lower single-null, LSN), and in the other case, the ion (del)B drift points away from the divertor X-point (upper single-null, USN), are compared. Inside of r/a=0.9, the turbulence characteristics (amplitude, flow direction, correlation lengths) are similar in both cases, while near r/a=0.92, a dramatic reversal of the poloidal flow of turbulence relative to the core flow direction is observed in plasmas with the ion (del)B drift pointing towards the divertor X-point. No such flow reversal is observed in plasmas with the ion (del)B drift pointing away from the divertor X-point. This poloidal flow reversal results in a significantly larger local shear in the poloidal turbulence flow velocity in plasmas with the ion (del)B drift pointing towards the divertor X-point. Additionally, these plasmas locally exhibit significant dispersion, with two distinct and counter-propagating turbulence modes. Likewise, the radial correlation length of the turbulence is reduced in these plasmas, consistent with biorthogonal decomposition measurements of dominant turbulence structures. The naturally occurring turbulence flow shear in these LSN plasmas may facilitate the LH transition that occurs at an input power of roughly one-half to one-third that of corresponding plasmas with the ion (del)B drift pointing away from the X-point

  8. Effect of aspect ratio on relationship between flow resistance and flow regime of two-phase flow in rectangular channel

    International Nuclear Information System (INIS)

    Yan Chaoxing; Yan Changqi; Sun Licheng; Xing Dianchuan; Wang Yang

    2013-01-01

    On the basis of visual observation, the effects of aspect ratio on relationship between flow resistance and flow regime were investigated experimentally for two-phase flow in three rectangular channels with the same cross-section width of 43 mm and different heights of 1.41, 3 and 10 mm, respectively. According to the criteria in terms of restriction factor C o , the former two channels belong to narrow channel, whereas the last one is conventional channel. The experimental results show that the two-phase pressure drops in rectangular channel with different aspect ratios have different variation trends with the increase of the gas velocity. For the 10 mm channel, the gravitational pressure drop makes the major percentage of total pressure drop at low gas velocity while the frictional pressure drop is dominant for the 1.41 mm and 3 mm channels. With the increase of the gas flow rate, the frictional pressure drop contributes more to total pressure drop. The range of churn flow can be distinguished from its pressure drop characteristic in 10 mm channel. (authors)

  9. Evaluation Influence: The Evaluation Event and Capital Flow in International Development.

    Science.gov (United States)

    Bell, David A

    2017-12-01

    Assessing program effectiveness in human development is central to informing foreign aid policy-making and organizational learning. Foreign aid effectiveness discussions have increasingly given attention to the devaluing effects of aid flow volatility. This study reveals that the external evaluation event influences actor behavior, serving as a volatility-constraining tool. A case study of a multidonor aid development mechanism served examining the influence of an evaluation event when considering anticipatory effects. The qualitative component used text and focus group data combined with individual interview data (organizations n = 10, including 26 individuals). Quantitative data included financial information on all 75 capital investments. The integrated theory of influence and model of alternative mechanisms used these components to identify the linkage between the evaluation event and capital flow volatility. Aid approved in the year of the midterm evaluation was disbursed by the mechanism with low capital volatility. Anticipating the evaluation event influenced behavior resulting in an empirical record that program outcomes were enhanced and the mechanism was an improved organization. Formative evaluations in a development program can trigger activity as an interim process. That activity provides for a more robust assessment of ultimate consequence of interest. Anticipating an evaluation can stimulate donor reality testing. The findings inform and strengthen future research on the influence of anticipating an evaluation. Closely examining activities before, during, and shortly after the evaluation event can aid development of other systematic methods to improve understanding this phenomenon, as well as improve donor effectiveness strategies.

  10. The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

    Science.gov (United States)

    Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

    2018-06-01

    In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.

  11. Effects of forskolin on cerebral blood flow: implications for a role of adenylate cyclase

    International Nuclear Information System (INIS)

    Wysham, D.G.; Brotherton, A.F.; Heistad, D.D.

    1986-01-01

    We have studied cerebral vascular effects of forskolin, a drug which stimulates adenylate cyclase and potentiates dilator effects of adenosine in other vascular beds. Our goals were to determine whether forskolin is a cerebral vasodilator and whether it potentiates cerebral vasodilator responses to adenosine. We measured cerebral blood flow with microspheres in anesthetized rabbits. Forskolin (10 micrograms/kg per min) increased blood flow (ml/min per 100 gm) from 39 +/- 5 (mean +/- S.E.) to 56 +/- 9 (p less than 0.05) in cerebrum, and increased flow to myocardium and kidney despite a decrease in mean arterial pressure. Forskolin did not alter cerebral oxygen consumption, which indicates that the increase in cerebral blood flow is a direct vasodilator effect and is not secondary to increased metabolism. We also examined effects of forskolin on the response to infusion of adenosine. Cerebral blood flow was measured during infusion of 1-5 microM/min adenosine into one internal carotid artery, under control conditions and during infusion of forskolin at 3 micrograms/kg per min i.v. Adenosine alone increased ipsilateral cerebral blood flow from 32 +/- 3 to 45 +/- 5 (p less than 0.05). Responses to adenosine were not augmented during infusion of forskolin. We conclude that forskolin is a direct cerebral vasodilator and forskolin does not potentiate cerebral vasodilator responses to adenosine

  12. Comparison of fractional flow reserve of composite Y-grafts with saphenous vein or right internal thoracic arteries.

    Science.gov (United States)

    Glineur, David; Boodhwani, Munir; Poncelet, Alain; De Kerchove, Laurent; Etienne, Pierre Yves; Noirhomme, Philippe; Deceuninck, Paul; Michel, Xavier; El Khoury, Gebrine; Hanet, Claude

    2010-09-01

    Composite Y-grafts, using the left internal thoracic artery as the inflow, allow a more efficient use of conduits without the need to touch a diseased ascending aorta. Among other conduits, the saphenous vein graft may be an alternative to the radial artery in elderly patients. We evaluated the hemodynamic characteristics of 17 composite Y-grafts made with the left internal thoracic artery anastomosed to the left anterior descending coronary artery in all cases and with either the free right internal thoracic artery (RITA group, n = 10) or a saphenous vein graft (SVG group, n = 7) implanted proximally to the left internal thoracic artery and distally to the circumflex territory 6 months after the operation. At baseline, the pressure gradient measured with a 0.014-inch pressure wire was minimal between the aorta and the internal thoracic artery stem (2 +/- 1 mm Hg), the internal thoracic artery and left anterior descending (4 +/- 2 mm Hg), the internal thoracic artery and left circumflex (3 +/- 1 mm Hg), and the saphenous vein graft and left circumflex (2 +/- 2 mm Hg). During hyperemia induced by adenosine, the pressure gradient increased significantly to 6 +/- 2 mm Hg in the internal thoracic artery stem, 9 +/- 4 mm Hg in the internal thoracic artery and left anterior descending artery, 9 +/- 3 mm Hg in the internal thoracic artery and left circumflex, and 7 +/- 4 mm Hg in the saphenous vein graft and left circumflex. Fractional flow reserve was 0.94 +/- 0.02 in internal thoracic artery stem, 0.90 +/- 0.04 mm Hg in the internal thoracic artery and left anterior descending, 0.91 +/- 0.03 mm Hg in the internal thoracic artery and left circumflex, and 0.92 +/- 0.06 mm Hg in the saphenous vein graft and left circumflex. No difference between the two types of composite Y-grafts was observed for pressure gradients or fractional flow reserve measured in internal thoracic artery stem or in distal branches. Composite Y-grafts with saphenous vein or right internal thoracic

  13. International Harmonisation Of Accounting Standards: The Case For A Mandatory Requirement For The Direct Method Of Reporting Operating Cash Flows

    OpenAIRE

    Christine Yap

    2011-01-01

    Even though standard setters have now embraced cash flow statements there remains ambivalence as to the best format (i.e. direct or indirect method) for disclosing cash flow from operations. In 1987 the FASB asserted that information about the gross amounts of cash receipts and cash payments is more relevant than information about the net amounts of cash receipts and payments. Yet apart from Australia and New Zealand, most standard setting bodies, including the International Accounting Standa...

  14. Effects of Car Accidents on Three-Lane Traffic Flow

    Directory of Open Access Journals (Sweden)

    Jianzhong Chen

    2014-01-01

    Full Text Available A three-lane traffic flow model is proposed to investigate the effect of car accidents on the traffic flow. The model is an extension of the full velocity difference (FVD model by taking into account the lane changing. The extended lane-changing rules are presented to model the lane-changing behaviour. The cases that the car accidents occupy the exterior or interior lane, the medium lane, and two lanes are studied by numerical simulations. The time-space diagrams and the current diagrams are presented, and the traffic jams are investigated. The results show that the car accident has a different effect on the traffic flow when it occupies different lanes. The car accidents have a more serious effect on the whole road when they occupy two lanes. The larger the density is, the greater the influence on the traffic flow becomes.

  15. Effects of rotation on flow in an asymmetric rib-roughened duct: LES study

    International Nuclear Information System (INIS)

    Borello, D.; Salvagni, A.; Hanjalić, K.

    2015-01-01

    Highlights: • Ribbed duct reproduces most of the phenomena occurring in internal cooling channels of blade turbines (rotor and stator). • LES analysis of the flow in a ribbed duct was carried out aiming at detecting the influence of rotation on the turbulence. • In destabilizing conditions, rotation enhances turbulence close to the ribbed duct thus enhancing removal of fluid from the wall and improving mixing. • In stabilizing conditions, turbulence is suppressed by rotation close to the ribbed wall. - Abstract: We report on large-eddy simulations (LES) of fully-developed asymmetric flow in a duct of a rectangular cross-section in which square-sectioned, equally-spaced ribs oriented perpendicular to the flow direction, were mounted on one of the walls. The configuration mimics a passage of internal cooling of a gas-turbine blade. The duct flow at a Reynolds number Re = 15,000 (based on hydraulic diameter D_h and bulk flow velocity U_0) was subjected to clock-wise (stabilising) and anti-clock-wise (destabilising) orthogonal rotation at a moderate rotational number Ro = ΩD_h/U_0 = 0.3, where Ω is the angular velocity. The LES results reproduced well the available experimental results of Coletti et al. (2011) (in the mid-plane adjacent to the ribbed wall) and provided insight into the whole duct complementing the reference PIV measurement. We analyzed the effects of stabilising and destabilising rotation on the flow, vortical structures and turbulence statistics by comparison with the non-rotating case. The analysis includes the identification of depth of penetration of the rib-effects into the bulk flow, influence of flow three-dimensionality and the role of secondary motions, all shown to be strongly affected by the rotation and its direction.

  16. Effect of the mitral valve on diastolic flow patterns

    International Nuclear Information System (INIS)

    Seo, Jung Hee; Vedula, Vijay; Mittal, Rajat; Abraham, Theodore; Dawoud, Fady; Luo, Hongchang; Lardo, Albert C.

    2014-01-01

    The leaflets of the mitral valve interact with the mitral jet and significantly impact diastolic flow patterns, but the effect of mitral valve morphology and kinematics on diastolic flow and its implications for left ventricular function have not been clearly delineated. In the present study, we employ computational hemodynamic simulations to understand the effect of mitral valve leaflets on diastolic flow. A computational model of the left ventricle is constructed based on a high-resolution contrast computed-tomography scan, and a physiological inspired model of the mitral valve leaflets is synthesized from morphological and echocardiographic data. Simulations are performed with a diode type valve model as well as the physiological mitral valve model in order to delineate the effect of mitral-valve leaflets on the intraventricular flow. The study suggests that a normal physiological mitral valve promotes the formation of a circulatory (or “looped”) flow pattern in the ventricle. The mitral valve leaflets also increase the strength of the apical flow, thereby enhancing apical washout and mixing of ventricular blood. The implications of these findings on ventricular function as well as ventricular flow models are discussed

  17. International projects of the Chair for waste and material flow management in the period 2010-2014

    International Nuclear Information System (INIS)

    Nelles, Michael

    2015-01-01

    The waste and material flow management must align progressively to the requirements of sustainable resource and climate protection targets. She has become a recycling economy. One of the key global challenges of the future is to ensure a sustainable, i.e. economically, environmentally and socially sustainable supply of raw materials and energy. In both areas, the recycling economy make an important contribution. For Germany, despite of the ambitious targets, a positive balance can be drawn. In particular, the positive environmental effects of prevention, recovery and disposal of waste are supported by numerous scientific studies. While the recycling economy has performed well in Germany, many countries in the world are still in the beginning of a sustainable waste management development. Our Chair for Waste and Material Flow Management at the Faculty of Agricultural and Environmental Sciences of the University of Rostock has been involved for over 15 years in international technology and knowledge transfer. The regional focus are the Arab and Asian region (esp. China) and for some years, the Baltic countries, Eastern Europe and South America. Often in the projects stand in the foreground, to inform key decision-makers on the state of technology and to work out possible administrative solutions and customized technical solutions together and implement. In addition, classic R and D projects in these regions have been processed. In the framework of student works, studies in other countries, amongst other things in Vietnam and Chile, are carried out. [de

  18. Numerical analysis of compressible steady, unsteady, and inviscid, viscous flows in ca scads and effects of viscosity on the flows

    International Nuclear Information System (INIS)

    Shirani, E.; Zirak, S.

    2001-01-01

    Compressible flows for unsteady, inviscid and viscous cases have been studied. Important features of flows such as formation of shock waves across the flow in an unsteady flow as well as interaction of shock waves with boundary layers and their effects on the flow around the blades have been analyzed. Jameson control volume approach was used to spatially integrate the flow equations and the fourth order Runge-Kutta method was used for time integration. The obtained finite difference equations were used to simulate inviscid and viscous flows in V KI cascades and the effects of viscosity, angle of attack, bal de pitches and back pressure on the flow were obtained. It was shown that when the flow was assumed inviscid, the error on the distribution of pressure on the blades were about ten percent. Finally, unsteady flow were simulated and formation of shock waves and their motions were analyzed

  19. Novel flow cytometric analysis of the progress and route of internalization of a monoclonal anti-carcinoembryonic antigen (CEA) antibody.

    Science.gov (United States)

    Ford, C H; Tsaltas, G C; Osborne, P A; Addetia, K

    1996-03-01

    A flow cytometric method of studying the internalization of a monoclonal antibody (Mab) directed against carcinoembryonic antigen (CEA) has been compared with Western blotting, using three human colonic cancer cell lines which express varying amounts of the target antigen. Cell samples incubated for increasing time intervals with fluoresceinated or unlabelled Mab were analyzed using flow cytometry or polyacrylamide gel electrophoresis and Western blotting. SDS/PAGE analysis of cytosolic and membrane components of solubilized cells from the cell lines provided evidence of non-degraded internalized anti-CEA Mab throughout seven half hour intervals, starting at 5 min. Internalized anti-CEA was detected in the case of high CEA expressing cell lines (LS174T, SKCO1). Very similar results were obtained with an anti-fluorescein flow cytometric assay. Given that these two methods consistently provided comparable results, use of flow cytometry for the detection of internalized antibody is suggested as a rapid alternative to most currently used methods for assessing antibody internalization. The question of the endocytic route followed by CEA-anti-CEA complexes was addressed by using hypertonic medium to block clathrin mediated endocytosis.

  20. Description of internal flow problems by a boundary integral method with dipole panels

    International Nuclear Information System (INIS)

    Krieg, R.; Hailfinger, G.

    1979-01-01

    In reactor safety studies the failure of single components is postulated or sudden accident loadings are assumed and the consequences are investigated. Often as a first consequence highly transient three dimensional flow problems occur. In contrast to classical flow problems, in most of the above cases the fluid velocities are relatively small whereas the accelerations assume high values. As a consequence both, viscosity effects and dynamic pressures which are proportional to the square of the fluid velocities are usually negligible. For cases, where the excitation times are considerably longer than the times necessary for a wave to traverse characteristic regions of the fluid field, also the fluid compressibility is negligible. Under these conditions boundary integral methods are an appropriate tool to deal with the problem. Flow singularities are distributed over the fluid boundaries in such a way that pressure and velocity fields are obtained which satisfy the boundary conditions. In order to facilitate the numerical treatment the fluid boundaries are approximated by a finite number of panels with uniform singularity distributions on each of them. Consequently the pressure and velocity field of the given problem may be obtained by superposition of the corresponding fields due to these panels with their singularity intensities as unknown factors. Then satisfying the boundary conditions in so many boundary points as panels have been introduced, yields a system of linear equations which in general allows for a unique determination of the unknown intensities. (orig./RW)

  1. 11th International Conference on Numerical Modeling of Space Plasma Flows: ASTRONUM-2016

    International Nuclear Information System (INIS)

    2017-01-01

    PREFACEThe Center for Space Plasma and Aeronomic Research (CSPAR) at the University of Alabama in Huntsville (UAH) and Maison de la Simulation at the French Alternative Energies and Atomic Energy Commission (Commissariat a l’energie atomique et aux energies alternatives, CEA) organized the 11th annual International Conference on Numerical Modeling of Space Plasma Flows (ASTRONUM-2016) on June 6—10, 2016 in Monterey, California, USA.The Program Committee consisted of Tahar Amari (CNRS Ecole Polytechnique, France), Edouard Audit (CEA/CNRS Maison de la Simulation, Gif-sur-Yvette, France, co-chair), Amitava Bhattacharjee (Princeton University, USA), Phillip Colella (Lawrence Berkeley National Laboratory, USA), Anthony Mezzacappa (University of Tennessee, Knoxville, USA), Ewald Müller (Max-Planck-Institute for Astrophysics, Garching, Germany), Nikolai Pogorelov (University of Alabama in Huntsville/CSPAR, USA, chair), Kazunari Shibata (Kyoto University, Japan), James Stone (Princeton University, USA), Jon Linker (Predictive Science, Inc., USA), and Gary P. Zank (University of Alabama in Huntsville, USA).The conference attracted 92 scientists representing different branches of the plasma simulation community. The distinctive feature of this conference is a combination of diverse research topics, all of which are essential for performing high-resolution, continuum mechanics and particle, simulations of physical phenomena in space physics and astrophysics. Among such topics were software packages for modeling and analyzing plasma flows; advanced numerical methods for space and astrophysical flows; large-scale fluid-based, kinetic, and hybrid simulations; turbulence and cosmic ray transport; and magnetohydrodynamics. The applications discussed included cosmology and galaxy formation, supernova explosions, physics of the Sun-heliosphere-magnetosphere environments, the interstellar medium and star formation, stellar physics, experimental plasma physics, astrophysical

  2. Welfare effects of the internalization of external cost

    International Nuclear Information System (INIS)

    Lijesen, M.; Korteweg, J.A.; Derriks, H.

    2009-03-01

    The effect of passing through the cost of external effects such as accidents, environment and noise to traffic and transport have been mapped. In nine out of the ten examined variants this 'internalization' will lead to an increase in welfare in the Netherlands. Internalization leads to a decrease of external costs of over 100 million to more than 1.7 billion euros annually. Internalization also brings about collection costs, international transfers and logistic adjustments. The balance of these effects varies from a welfare loss of 20 million euros to a welfare increase of 1.2 billion euros annually. [nl

  3. The effects of radiogenic heat on groundwater flow

    International Nuclear Information System (INIS)

    Beddoes, R.J.; Tammemagi, H.Y.

    1986-03-01

    The effects of radiogenic heat released by a nuclear waste repository on the groundwater flow in the neighbouring rock mass is reviewed. The report presents an overview of the hydrogeologic properties of crystalline rocks in the Canadian Shield and also describes the mathematical theory of groundwater flow and heat transfer in both porous media and fractured rock. Numerical methods for the solution of the governing equations are described. A number of case histories are described where analyses of flow systems have been performed both with and without radiogenic heat sources. A number of relevant topics are reviewed such as the role of the porous medium model, boundary conditions and, most importantly, the role of complex coupled processes where the effects of heat and water flow are intertwined with geochemical and mechanical processes. The implications to radioactive waste disposal are discussed

  4. Internal homogenization: effective permittivity of a coated sphere.

    Science.gov (United States)

    Chettiar, Uday K; Engheta, Nader

    2012-10-08

    The concept of internal homogenization is introduced as a complementary approach to the conventional homogenization schemes, which could be termed as external homogenization. The theory for the internal homogenization of the permittivity of subwavelength coated spheres is presented. The effective permittivity derived from the internal homogenization of coreshells is discussed for plasmonic and dielectric constituent materials. The effective model provided by the homogenization is a useful design tool in constructing coated particles with desired resonant properties.

  5. Effects of peatland drainage management on peak flows

    OpenAIRE

    C. E. Ballard; N. McIntyre; H. S. Wheater

    2011-01-01

    Open ditch drainage has historically been a common land management practice in upland blanket peats, particularly in the UK. However, peatland drainage is now generally considered to have adverse effects on the upland environment, including increased peak flows. As a result, drain blocking has become a common management strategy in the UK over recent years, although there is only anecdotal evidence to suggest that this might decrease peak flows. The change in the hydrologica...

  6. Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

    International Nuclear Information System (INIS)

    Zhang, S; Sobota, A; Van Veldhuizen, E M; Bruggeman, P J

    2015-01-01

    This work investigates the flow dynamics of a radio-frequency (RF) non-equilibrium argon atmospheric pressure plasma jet. The RF power is at a frequency of 50 Hz or 20 kHz. Combined flow pattern visualizations (obtained by shadowgraphy) and gas temperature distributions (obtained by Rayleigh scattering) are used to study the formation of transient vortex structures in initial flow field shortly after the plasma is switched on and off in the case of 50 Hz modulation. The transient vortex structures correlate well with observed temperature differences. Experimental results of the fast modulated (20 kHz) plasma jet that does not induce changes of the gas temperature are also presented. The latter result suggests that momentum transfer by ions does not have dominant effect on the flow pattern close to the tube. It is argued that the increased gas temperature and corresponding gas velocity increase at the tube exit due to the plasma heating increases the admixing of surrounding air and reduces the effective potential core length. With increasing plasma power a reduction of the effective potential core length is observed with a minimum length for 5.6 W after which the length extends again. Possible mechanisms related to viscosity effects and ionic momentum transfer are discussed. (paper)

  7. The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery.

    LENUS (Irish Health Repository)

    Halpenny, M

    2012-02-03

    OBJECTIVE: To quantify the effects of fenoldopam, 0.1 microg\\/kg\\/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: University teaching hospital, single institution. PARTICIPANTS: Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization. INTERVENTIONS: A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis. MEASUREMENTS AND MAIN RESULTS: Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg\\/kg\\/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +\\/- 12 to 35 +\\/- 10 mL\\/min) in patients who received fenoldopam. No significant changes occurred in the placebo group. CONCLUSIONS: The findings indicate that fenoldopam, 0.1 microg\\/kg\\/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

  8. The International River Interface Cooperative: Public Domain Software for River Flow and Morphodynamics (Invited)

    Science.gov (United States)

    Nelson, J. M.; Shimizu, Y.; McDonald, R.; Takebayashi, H.

    2009-12-01

    The International River Interface Cooperative is an informal organization made up of academic faculty and government scientists with the goal of developing, distributing and providing education for a public-domain software interface for modeling river flow and morphodynamics. Formed in late 2007, the group released the first version of this interface (iRIC) in late 2009. iRIC includes models for two and three-dimensional flow, sediment transport, bed evolution, groundwater-surface water interaction, topographic data processing, and habitat assessment, as well as comprehensive data and model output visualization, mapping, and editing tools. All the tools in iRIC are specifically designed for use in river reaches and utilize common river data sets. The models are couched within a single graphical user interface so that a broad spectrum of models are available to users without learning new pre- and post-processing tools. The first version of iRIC was developed by combining the USGS public-domain Multi-Dimensional Surface Water Modeling System (MD_SWMS), developed at the USGS Geomorphology and Sediment Transport Laboratory in Golden, Colorado, with the public-domain river modeling code NAYS developed by the Universities of Hokkaido and Kyoto, Mizuho Corporation, and the Foundation of the River Disaster Prevention Research Institute in Sapporo, Japan. Since this initial effort, other Universities and Agencies have joined the group, and the interface has been expanded to allow users to integrate their own modeling code using Executable Markup Language (XML), which provides easy access and expandability to the iRIC software interface. In this presentation, the current components of iRIC are described and results from several practical modeling applications are presented to illustrate the capabilities and flexibility of the software. In addition, some future extensions to iRIC are demonstrated, including software for Lagrangian particle tracking and the prediction of

  9. Effects on haematological parameters and pathology of internal ...

    African Journals Online (AJOL)

    Effects on haematological parameters and pathology of internal organs of Trypanosoma brucei brucei infected albino rats. ... Group A served as the control (uninfected). ... The gross pathological effects on the internal organs showed significant enlargement of the spleen (splenomegaly) and slight enlargement of the liver ...

  10. Rarefaction effects in gas flows over curved surfaces

    Science.gov (United States)

    Dongari, Nishanth; White, Craig; Scanlon, Thomas J.; Zhang, Yonghao; Reese, Jason M.

    2012-11-01

    The fundamental test case of gas flow between two concentric rotating cylinders is considered in order to investigate rarefaction effects associated with the Knudsen layers over curved surfaces. We carry out direct simulation Monte Carlo simulations covering a wide range of Knudsen numbers and accommodation coefficients, and for various outer-to-inner cylinder radius ratios. Numerical data is compared with classical slip flow theory and a new power-law (PL) wall scaling model. The PL model incorporates Knudsen layer effects in near-wall regions by taking into account the boundary limiting effects on the molecular free paths. The limitations of both theoretical models are explored with respect to rarefaction and curvature effects. Torque and velocity profile comparisons also convey that mere prediction of integral flow parameters does not guarantee the accuracy of a theoretical model, and that it is important to ensure that prediction of the local flowfield is in agreement with simulation data.

  11. Effect of toroidal plasma flow and flow shear on global MHD modes

    International Nuclear Information System (INIS)

    Chu, M.S.; Greene, J.M.; Jensen, T.H.; Miller, R.L.; Bondeson, A.; Johnson, R.W.; Mauel, M.E.

    1995-01-01

    The effect of a subsonic toroidal flow on the linear magnetohydrodynamic stability of a tokamak plasma surrounded by an external resistive wall is studied. A complex non-self-adjoint eigenvalue problem for the stability of general kink and tearing modes is formulated, solved numerically, and applied to high β tokamaks. Results indicate that toroidal plasma flow, in conjunction with dissipation in the plasma, can open a window of stability for the position of the external wall. In this window, stable plasma beta values can significantly exceed those predicted by the Troyon scaling law with no wall. Computations utilizing experimental data indicate good agreement with observations

  12. Hall effects on MHD flow past an accelerated plate

    Directory of Open Access Journals (Sweden)

    Deka R.K.

    2008-01-01

    Full Text Available The simultaneous effects of rotation and Hall current on the hydromagnetic flow past an accelerated horizontal plate relative to a rotating fluid is presented. It is found that for given values of m (Hall parameter, M (Hartmann number and an imposed rotation parameter Ω satisfying Ω = M 2m/(1 + m2, the transverse motion (transverse to the main flow disappears and the fluid moves in the direction of the plate only. The effects of the parameters m, M and Ω on the axial and transverse velocity profiles are shown graphically, whereas the effects of the parameters on the skin-friction components are shown by tabular values.

  13. MONITORING INTERNATIONAL MIGRATION FLOWS IN EUROPE - TOWARDS A STATISTICAL-DATA BASE COMBINING DATA FROM DIFFERENT SOURCES

    NARCIS (Netherlands)

    WILLEKENS, F

    1994-01-01

    The paper reviews techniques developed in demography, geography and statistics that are useful for bridging the gap between available data on international migration flows and the information required for policy making and research. The basic idea of the paper is as follows: to establish a coherent

  14. Surface roughness effects on heat transfer in Couette flow

    International Nuclear Information System (INIS)

    Elia, G.G.

    1981-01-01

    A cell theory for viscous flow with rough surfaces is applied to two basic illustrative heat transfer problems which occur in Couette flow. Couette flow between one adiabatic surface and one isothermal surface exhibits roughness effects on the adiabatic wall temperature. Two types of rough cell adiabatic surfaces are studied: (1) perfectly insulating (the temperature gradient vanishes at the boundary of each cell); (2) average insulating (each cell may gain or lose heat but the total heat flow at the wall is zero). The results for the roughness on a surface in motion are postulated to occur because of fluid entrainment in the asperities on the moving surface. The symmetry of the roughness effects on thermal-viscous dissipation is discussed in detail. Explicit effects of the roughness on each surface, including combinations of roughness values, are presented to enable the case where the two surfaces may be from different materials to be studied. The fluid bulk temperature rise is also calculated for Couette flow with two ideal adiabatic surfaces. The effect of roughness on thermal-viscous dissipation concurs with the viscous hydrodynamic effect. The results are illustrated by an application to lubrication. (Auth.)

  15. Experimental Observations on a Low Strain Counter-Flow Diffusion Flame: Flow and Bouyancy Effects

    Science.gov (United States)

    Sutula, J. A.; Torero, J. L.; Ezekoye, O. A.

    1999-01-01

    Diffusion flames are of great interest in fire safety and many industrial processes. The counter-flow configuration provides a constant strain flow, and therefore is ideal to study the structure of diffusion flames. Most studies have concentrated on the high velocity, high strain limit, since buoyantly induced instabilities will disintegrate the planar flame as the velocity decreases. Only recently, experimental studies in microgravity conditions have begun to explore the low strain regimes. Numerical work has shown the coupling between gas phase reaction rates, soot reaction rates, and radiation. For these programs, size, geometry and experimental conditions have been chosen to keep the flame unaffected by the physical boundaries. When the physical boundaries can not be considered infinitely far from the reaction zone discrepancies arise. A computational study that includes boundary effects and accounts for the deviations occurring when the major potential flow assumptions are relaxed was presented by Borlik et al. This development properly incorporates all heat loss terms and shows the possibility of extinction in the low strain regime. A major constraint of studying the low strain regime is buoyancy. Buoyant instabilities have been shown to have a significant effect on the nature of reactants and heat transport, and can introduce instabilities on the flow that result in phenomena such as flickering or fingering. The counter-flow configuration has been shown to provide a flame with no symmetry disrupting instabilities for inlet velocities greater than 50 mm/s. As the velocity approaches this limit, the characteristic length of the experiment has to be reduced to a few millimetres so as to keep the Rayleigh number (Ra(sub L) = (Beta)(g(sub 0))(L(exp 3) del T)/(alpha(v))) below 2000. In this work, a rectangular counter-flow burner was used to study a two-dimensional counter-flow diffusion flame. Flow visualisation and Particle Image Velocimetry served to describe

  16. Wind-induced flow velocity effects on nutrient concentrations at Eastern Bay of Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Jianwei; Gao, Xiaomeng; Wang, Wencai; Acharya, Kumud

    2017-07-01

    Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.

  17. Numerical simulations of the internal flow pattern of a vortex pump compared to the Hamel-Oseen vortex

    International Nuclear Information System (INIS)

    Gerlach, Angela; Preuss, Enrico; Thamsen, Paul Uwe; Lykholt-Ustrup, Flemming

    2017-01-01

    We did a numerical study of the internal flow field of a vortex pump. Five operating points were considered and validated through a measured characteristic curve. The internal flow pattern of a vortex pump was analyzed and compared to the Hamel-Oseen vortex model. The calculated flow field was assessed with respect to the circumferential velocity, the vorticity and the axial velocity. Whereas the trajectories of the circumferential velocity were largely in line with the Hamel-Oseen vortex model, the opposite was true for vorticity. Only the vorticity at strong part load was in line with the predictions of the Hamel-Oseen vortex model. We therefore compared the circumferential velocity and vorticity for strong part load operation to the analytical predictions of the Hamel-Oseen vortex model. The simulated values were below the analytical values. The study therefore suggests that a vortex similar to the Hamel-Oseen vortex is only present at the strong part load operation

  18. Numerical simulations of the internal flow pattern of a vortex pump compared to the Hamel-Oseen vortex

    Energy Technology Data Exchange (ETDEWEB)

    Gerlach, Angela; Preuss, Enrico; Thamsen, Paul Uwe [Institute of Fluid System Dynamics, Technische Universitaet, Berlin (Germany); Lykholt-Ustrup, Flemming [Grundfos Holding A/S, Bjerringbro (Denmark)

    2017-04-15

    We did a numerical study of the internal flow field of a vortex pump. Five operating points were considered and validated through a measured characteristic curve. The internal flow pattern of a vortex pump was analyzed and compared to the Hamel-Oseen vortex model. The calculated flow field was assessed with respect to the circumferential velocity, the vorticity and the axial velocity. Whereas the trajectories of the circumferential velocity were largely in line with the Hamel-Oseen vortex model, the opposite was true for vorticity. Only the vorticity at strong part load was in line with the predictions of the Hamel-Oseen vortex model. We therefore compared the circumferential velocity and vorticity for strong part load operation to the analytical predictions of the Hamel-Oseen vortex model. The simulated values were below the analytical values. The study therefore suggests that a vortex similar to the Hamel-Oseen vortex is only present at the strong part load operation.

  19. Cost effectiveness methodology for evaluating Korean international communication system alternatives.

    OpenAIRE

    Hwang, Tae Kyun.

    1987-01-01

    Approved for public release; distribution in unlimited. Cost and Effectiveness models are developed by using of cost-effectiveness technique for fiber optic cable and satellite communication media. The models are applied to the Korean international communication problem. Alternative selection is required since the two medias different in cost and effectiveness. The major difficulties encountered were data gathering and measuring the effectiveness of the Korean international ...

  20. The effect of blood cell count on coronary flow in patients with coronary slow flow phenomenon.

    Science.gov (United States)

    Soylu, Korhan; Gulel, Okan; Yucel, Huriye; Yuksel, Serkan; Aksan, Gokhan; Soylu, Ayşegül İdil; Demircan, Sabri; Yılmaz, Ozcan; Sahin, Mahmut

    2014-09-01

    The coronary slow flow phenomenon (CSFP) is a coronary artery disease with a benign course, but its pathological mechanisms are not yet fully understood.The purpose of this controlled study was to investigate the cellular content of blood in patients diagnosed with CSFP and the relationship of this with coronary flow rates. Selective coronary angiographies of 3368 patients were analyzed to assess Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) values. Seventy eight of them had CSFP, and their demographic and laboratory findings were compared with 61 patients with normal coronary flow. Patients' demographic characteristics were similar in both groups. Mean corrected TFC (cTFC) values were significantly elevated in CSFP patients (p<0.001). Furthermore, hematocrit and hemoglobin values, and eosinophil and basophil counts of the CSFP patients were significantly elevated compared to the values obtained in the control group (p=0.005, p=0.047, p=0.001 and p=0.002, respectively). The increase observed in hematocrit and eosinophil levels showed significant correlations with increased TFC values (r=0.288 and r=0.217, respectively). Significant changes have been observed in the cellular composition of blood in patients diagnosed with CSFP as compared to the patients with normal coronary blood flow. The increases in hematocrit levels and in the eosinophil and basophil counts may have direct or indirect effects on the rate of coronary blood flow.

  1. Effects of swirl in turbulent pipe flows : computational studies

    Energy Technology Data Exchange (ETDEWEB)

    Nygaard, Frode

    2011-07-01

    The primary objective of this doctoral thesis was to investigate the effect of swirl in steady turbulent pipe flows. The work has been carried out by a numerical approach, with direct numerical simulations as the method of choice. A key target to pursue was the effects of the swirl on the wall friction in turbulent pipe flows. The motivation came from studies of rotating pipe flows in which drag reduction was achieved. Drag reduction was reported to be due to the swirl favourably influencing the coherent turbulent structures in the near-wall region. Based on this, it was decided to investigate if similar behaviour could be obtained by inducing a swirl in a pipe with a stationary wall. To do a thorough investigation of the general three-dimensional swirl flow and particularly of the swirl effects; chosen variations of mean and turbulent flow parameters were explored together with complementary flow visualizations. Two different approaches in order to induce the swirl in the turbulent pipe flow, have been carried out. However, the present thesis might be regarded to be comprised of three parts. The first part consists of the first approach to induce the swirl. Here a prescribed circumferential force was implemented in a serial open source Navier-Stokes solver. In the second approach, the swirl was intended induced by implementing structures at the wall. Simulations of flows through a pipe with one or more helical fin(s) at the pipe wall was decided to be performed. In order to pursue this approach, it was found necessary to do a parallelization of the existing serial numerical code. The key element of this parallelization has been included as a part of the present work. Additionally, the helical fin(s) were implemented into the code by use of an immersed boundary method. A validation of this work is also documented in the thesis. The work done by parallelizing the code and implementing an immersed boundary method constitutes the second part of the present thesis. The

  2. Numerical investigation of MHD flow with Soret and Dufour effect

    Science.gov (United States)

    Hayat, Tasawar; Nasir, Tehreem; Khan, Muhammad Ijaz; Alsaedi, Ahmed

    2018-03-01

    This paper describes the flow due to an exponentially curved surface subject to Soret and Dufour effects. Nonlinear velocity is considered. Exponentially curved stretchable sheet induced the flow. Fluid is electrical conducting through constant applied magnetic field. The governing flow expressions are reduced to ordinary ones and then tackled by numerical technique (Built-in-Shooting). Impacts of various flow variables on the dimensionless velocity, concentration and temperature fields are graphically presented and discussed in detail. Skin friction coefficient and Sherwood and Nusselt numbers are studied through graphs. Furthermore it is observed that Soret and Dufour variables regulate heat and mass transfer rates. It is also noteworthy that velocity decays for higher magnetic variable. Skin friction magnitude decays via curvature and magnetic variables. Also mass transfer gradient or rate of mass transport enhances for higher estimations of curvature parameter and Schmidt number.

  3. Field-effect Flow Control in Polymer Microchannel Networks

    Science.gov (United States)

    Sniadecki, Nathan; Lee, Cheng S.; Beamesderfer, Mike; DeVoe, Don L.

    2003-01-01

    A new Bio-MEMS electroosmotic flow (EOF) modulator for plastic microchannel networks has been developed. The EOF modulator uses field-effect flow control (FEFC) to adjust the zeta potential at the Parylene C microchannel wall. By setting a differential EOF pumping rate in two of the three microchannels at a T-intersection with EOF modulators, the induced pressure at the intersection generated pumping in the third, field-free microchannel. The EOF modulators are able to change the magnitude and direction of the pressure pumping by inducing either a negative or positive pressure at the intersection. The flow velocity is tracked by neutralized fluorescent microbeads in the microchannels. The proof-of-concept of the EOF modulator described here may be applied to complex plastic ,microchannel networks where individual microchannel flow rates are addressable by localized induced-pressure pumping.

  4. Effects of equipment and technique on peak flow measurements

    Directory of Open Access Journals (Sweden)

    O'Driscoll B Ronan

    2006-06-01

    Full Text Available Abstract Background Different lung function equipment and different respiratory manoeuvres may produce different Peak Expiratory Flow (PEF results. Although the PEF is the most common lung function test, there have been few studies of these effects and no previous study has evaluated both factors in a single group of patients. Methods We studied 36 subjects (PEF range 80–570 l/min. All patients recorded PEF measurements using a short rapid expiration following maximal inspiration (PEF technique or a forced maximal expiration to residual volume (FVC technique. Measurements were made using a Wright's peak flow meter, a turbine spirometer and a Fleisch pneumotachograph spirometer. Results The mean PEF was 8.7% higher when the PEF technique was used (compared with FVC technique, p Conclusion Peak flow measurements are affected by the instruction given and by the device and Peak Flow scale used. Patient management decisions should not be based on PEF measurement made on different instruments.

  5. Effects of physical properties on thermo-fluids cavitating flows

    Science.gov (United States)

    Chen, T. R.; Wang, G. Y.; Huang, B.; Li, D. Q.; Ma, X. J.; Li, X. L.

    2015-12-01

    The aims of this paper are to study the thermo-fluid cavitating flows and to evaluate the effects of physical properties on cavitation behaviours. The Favre-averaged Navier-Stokes equations with the energy equation are applied to numerically investigate the liquid nitrogen cavitating flows around a NASA hydrofoil. Meanwhile, the thermodynamic parameter Σ is used to assess the thermodynamic effects on cavitating flows. The results indicate that the thermodynamic effects on the thermo-fluid cavitating flows significantly affect the cavitation behaviours, including pressure and temperature distribution, the variation of physical properties, and cavity structures. The thermodynamic effects can be evaluated by physical properties under the same free-stream conditions. The global sensitivity analysis of liquid nitrogen suggests that ρv, Cl and L significantly influence temperature drop and cavity structure in the existing numerical framework, while pv plays the dominant role when these properties vary with temperature. The liquid viscosity μl slightly affects the flow structure via changing the Reynolds number Re equivalently, however, it hardly affects the temperature distribution.

  6. Effective flow-accelerated corrosion programs in nuclear facilities

    International Nuclear Information System (INIS)

    Esselman, Thomas C.; McBrine, William J.

    2004-01-01

    Piping Flow-Accelerated Corrosion Programs in nuclear power generation facilities are classically comprised of the selection of inspection locations with the assistance of a predictive methodology such as the Electric Power Research Institute computer codes CHECMATE or CHECWORKS, performing inspections, conducting structural evaluations on the inspected components, and implementing the appropriate sample expansion and corrective actions. Performing such a sequence of steps can be effective in identifying thinned components and implementing appropriate short term and long term actions necessary to resolve flow-accelerated corrosion related problems. A maximally effective flow-accelerated corrosion (FAC) program requires an understanding of many programmatic details. These include the procedural control of the program, effective use of historical information, managing the activities performed during a limited duration outage, allocating resources based on risk allocation, having an acute awareness of how the plant is operated, investigating components removed from the plant, and several others. This paper will describe such details and methods that will lead to a flow-accelerated corrosion program that effectively minimizes the risk of failure due to flow-accelerated corrosion and provide full and complete documentation of the program. (author)

  7. Measurement of Blood Flow in an Intracranial Artery Bypass From the Internal Maxillary Artery by Intraoperative Duplex Sonography.

    Science.gov (United States)

    Yu, Zaitao; Shi, Xiang'en; Brohi, Shams Raza; Qian, Hai; Liu, Fangjun; Yang, Yang

    2017-02-01

    This study explored the hemodynamic characteristics of a subcranial-intracranial bypass from the internal maxillary artery by measuring blood flow on intraoperative duplex sonography. The hemodynamic parameters of the internal maxillary artery (n = 20), radial artery (n = 20), internal maxillary artery-middle cerebral artery bypass (n = 42), and internal maxillary artery-posterior cerebral artery bypass (n = 9) were measured by intraoperative duplex sonography. There was no significant difference in the internal diameters of the internal maxillary and radial arteries (mean ± SD, 2.51 ± 0.34 versus 2.56 ± 0.22 mm; P = .648). The mean radial artery graft length for subcranial-intracranial bypasses was 88.5 ± 12.78 mm (95% confidence interval [CI], 80.8-90.2 mm). Internal maxillary artery-middle cerebral artery bypasses required a shorter radial artery graft than internal maxillary artery-posterior cerebral artery bypasses (77.8 ± 2.47 versus 104.8 ± 4.77 mm; P = .001). The mean flow volumes were 85.3 ± 18.5 mL/min (95% CI, 76.6-93.9 mL/min) for the internal maxillary artery, 72.6 ± 26.4 mL/min (95% CI, 64.3-80.9 mL/min) for internal maxillary artery-middle cerebral artery bypasses, and 45.4 ± 6.7 mL/min (95% CI, 40.7-50.0 mL/min) for internal maxillary artery-posterior cerebral artery bypasses. All grafts were opened after the success of the salvage procedures had been established, and the early patency rates (1 month after the operation) were 95% for internal maxillary artery-middle cerebral artery bypasses and 100% the internal maxillary artery-posterior cerebral artery bypasses. Measurement of blood flow by intraoperative sonography can be helpful in decision making and predicting graft patency and success after neurosurgical bypass procedures. © 2016 by the American Institute of Ultrasound in Medicine.

  8. Flow and axial dispersion in a sinusoidal-walled tube: Effects of inertial and unsteady flows

    Science.gov (United States)

    Richmond, Marshall C.; Perkins, William A.; Scheibe, Timothy D.; Lambert, Adam; Wood, Brian D.

    2013-12-01

    In this work, we consider a sinusoidal-walled tube (a three-dimensional tube with sinusoidally-varying diameter) as a simplified conceptualization of flow in porous media. Direct numerical simulation using computational fluid dynamics (CFD) methods was used to compute velocity fields by solving the Navier-Stokes equations, and also to numerically solve the volume averaging closure problem, for a range of Reynolds numbers (Re) spanning the low-Re to inertial flow regimes, including one simulation at Re=449 for which unsteady flow was observed. The longitudinal dispersion observed for the flow was computed using a random walk particle tracking method, and this was compared to the longitudinal dispersion predicted from a volume-averaged macroscopic mass balance using the method of volume averaging; the results of the two methods were consistent. Our results are compared to experimental measurements of dispersion in porous media and to previous theoretical results for both the low-Re, Stokes flow regime and for values of Re representing the steady inertial regime. In the steady inertial regime, a power-law increase in the effective longitudinal dispersion (DL) with Re was found, and this is consistent with previous results. This rapid rate of increase is caused by trapping of solute in expansions due to flow separation (eddies). One unsteady (but non-turbulent) flow case (Re=449) was also examined. For this case, the rate of increase of DL with Re was smaller than that observed at lower Re. Velocity fluctuations in this regime lead to increased rates of solute mass transfer between the core flow and separated flow regions, thus diminishing the amount of tailing caused by solute trapping in eddies and thereby reducing longitudinal dispersion. The observed tailing was further explored through analysis of concentration skewness (third moment) and its assymptotic convergence to conventional advection-dispersion behavior (skewness = 0). The method of volume averaging was

  9. Sub-Grid Modeling of Electrokinetic Effects in Micro Flows

    Science.gov (United States)

    Chen, C. P.

    2005-01-01

    Advances in micro-fabrication processes have generated tremendous interests in miniaturizing chemical and biomedical analyses into integrated microsystems (Lab-on-Chip devices). To successfully design and operate the micro fluidics system, it is essential to understand the fundamental fluid flow phenomena when channel sizes are shrink to micron or even nano dimensions. One important phenomenon is the electro kinetic effect in micro/nano channels due to the existence of the electrical double layer (EDL) near a solid-liquid interface. Not only EDL is responsible for electro-osmosis pumping when an electric field parallel to the surface is imposed, EDL also causes extra flow resistance (the electro-viscous effect) and flow anomaly (such as early transition from laminar to turbulent flow) observed in pressure-driven microchannel flows. Modeling and simulation of electro-kinetic effects on micro flows poses significant numerical challenge due to the fact that the sizes of the double layer (10 nm up to microns) are very thin compared to channel width (can be up to 100 s of m). Since the typical thickness of the double layer is extremely small compared to the channel width, it would be computationally very costly to capture the velocity profile inside the double layer by placing sufficient number of grid cells in the layer to resolve the velocity changes, especially in complex, 3-d geometries. Existing approaches using "slip" wall velocity and augmented double layer are difficult to use when the flow geometry is complicated, e.g. flow in a T-junction, X-junction, etc. In order to overcome the difficulties arising from those two approaches, we have developed a sub-grid integration method to properly account for the physics of the double layer. The integration approach can be used on simple or complicated flow geometries. Resolution of the double layer is not needed in this approach, and the effects of the double layer can be accounted for at the same time. With this

  10. Numerical simulation of internal and near-nozzle flow of a gasoline direct injection fuel injector

    Science.gov (United States)

    Saha, Kaushik; Som, Sibendu; Battistoni, Michele; Li, Yanheng; Quan, Shaoping; Senecal, Peter Kelly

    2015-12-01

    A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multi-hole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from, the Engine Combustion Network (ECN). Simulations have been carried out for the fixed needle lift. Effects of turbulence, compressibility and, non-condensable gases have been considered in this work. Standard k—ɛ turbulence model has been used to model the turbulence. Homogeneous Relaxation Model (HRM) coupled with Volume of Fluid (VOF) approach has been utilized to capture the phase change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine non-flashing and evaporative, non-flashing and non-evaporative, and flashing conditions. Inside the nozzle holes mild cavitation-like and in the near-nozzle region flash boiling phenomena have been predicted in this study when liquid fuel is subjected to superheated ambiance. Noticeable hole to hole variation has been also observed in terms of mass flow rates for all the holes under both flashing and non-flashing conditions.

  11. A Numerical and Experimental Study of Ejector Internal Flow Structure and Geometry Modification for Maximized Performance

    Science.gov (United States)

    Falsafioon, Mehdi; Aidoun, Zine; Poirier, Michel

    2017-12-01

    A wide range of industrial refrigeration systems are good candidates to benefit from the cooling and refrigeration potential of supersonic ejectors. These are thermally activated and can use waste heat recovery from industrial processes where it is abundantly generated and rejected to the environment. In other circumstances low cost heat from biomass or solar energy may also be used in order to produce a cooling effect. Ejector performance is however typically modest and needs to be maximized in order to take full advantage of the simplicity and low cost of the technology. In the present work, the behavior of ejectors with different nozzle exit positions has been investigated using a prototype as well as a CFD model. The prototype was used in order to measure the performance advantages of refrigerant (R-134a) flowing inside the ejector. For the CFD model, it is assumed that the ejectors are axi-symmetric along x-axis, thus the generated model is in 2D. The preliminary CFD results are validated with experimental data over a wide range of conditions and are in good accordance in terms of entrainment and compression ratios. Next, the flow patterns of four different topologies are studied in order to discuss the optimum geometry in term of ejector entrainment improvement. Finally, The numerical simulations were used to find an optimum value corresponding to maximized entrainment ratio for fixed operating conditions.

  12. Effect of trailing edge ramp on cavity flow structures and pressure drag

    International Nuclear Information System (INIS)

    Pey, Yin Yin; Chua, Leok Poh; Siauw, Wei Long

    2014-01-01

    Highlights: • Trailing edge ramps were used to reduce unsteadiness and pressure drag of a cavity. • Proper Orthogonal Decomposition was used to educe the coherent structures. • The 30° ramp was successful in redistributing the energy content within the cavity. • The 30° ramp guides the flow smoothly out of the cavity, reducing flow impingement. • A substantial reduction of pressure drag was achieved by the 30° ramp. -- Abstract: The effects of trailing edge ramp modifications on time-averaged velocity and pressure distributions within a cavity with a length to depth ratio of 2, at a speed of 15 m/s were investigated. The ramp angles were varied at 30°, 45° and 60° and ramp heights were varied at 0.25 times and 0.5 times of cavity depth. The mean flow within the cavity differed significantly from the baseline case when ramp angle was 30° and 45° with ramp height 0.5 times of cavity depth. At these 2 configurations, moment about the center of the cavity floor was reduced significantly. These could be attributed to the more steady flow within the cavity as compared to the baseline case. Spatial correlation of velocity in the cavity of ramp angle 30° showed that internal cavity flow was less sensitive to flow changes in the shear layer as compared to the baseline case. In the same cavity, snapshot Proper Orthogonal Decomposition revealed a redistribution of energy content where energetic structures exist only in the shear layer as opposed to energetic structures in both the shear layer and internal cavity for the baseline case. A reduction of pressure drag was also observed as the gentle ramp angle of 30° guides the flow smoothly out of the cavity and reduces trailing edge impingement

  13. Balloon test occlusion of the internal carotid artery with stable xenon/CT cerebral blood flow imaging

    International Nuclear Information System (INIS)

    Erba, S.M.; Horton, J.A.; Latchaw, R.E.; Yonas, H.; Sekhar, L.; Schramm, V.; Pentheny, S.

    1988-01-01

    We describe a technique to predict preoperatively the safety of permanently occluding an internal carotid artery. The method was performed by imaging stable xenon cerebral blood flow (CBF) with the internal carotid artery both open and temporarily occluded with a nondetachable balloon on a double lumen Swan-Ganz catheter. Patients were those in whom we planned to sacrifice the internal carotid artery (those with giant or inaccessible aneurysms) or those in whom such a sacrifice was at least likely (those with skull base tumors). Patients were divided into three groups on the basis of a comparison of occluded and nonoccluded CBF values. Group-I patients had no significant change in CBF with internal carotid artery occlusion; group-II patients showed a symmetric decrease in CBF; and group-III patients had an asymmetric decrease in CBF, always greater on the occluded side. A fourth group clinically failed to tolerate even brief carotid occlusion. The internal carotid artery in one patients from group III was sacrificed at surgery: the size and shape of his postoperative infarct corresponded almost exactly to the area of asymmetrically decreased CBF on his occluded study. The data suggest that if surgery is likely to result in permanent occlusion of the internal carotid artery, then patients who are at risk for delayed neurologic injury due to a compromised cerebral blood flow should have arterial bypass grafts before such surgery is performed

  14. Effects of internally deposited alpha emitters

    International Nuclear Information System (INIS)

    Rundo, J.; Schlenker, R.A.; Stebbings, J.H.

    1985-01-01

    This study seeks to identify and quantify the human health effects of occupational exposures to radium, use the health effects data from the radium study to predict responses to other alpha-emitting and/or bone-seeking radionuclides at occupational exposure levels and above, and predict the effects of these radionuclides, specifically environmental radium and its daughters, at nonoccupational exposure levels. 14 refs

  15. Effects of shear flow on phase nucleation and crystallization.

    Science.gov (United States)

    Mura, Federica; Zaccone, Alessio

    2016-04-01

    Classical nucleation theory offers a good framework for understanding the common features of new phase formation processes in metastable homogeneous media at rest. However, nucleation processes in liquids are ubiquitously affected by hydrodynamic flow, and there is no satisfactory understanding of whether shear promotes or slows down the nucleation process. We developed a classical nucleation theory for sheared systems starting from the molecular level of the Becker-Doering master kinetic equation and we analytically derived a closed-form expression for the nucleation rate. The theory accounts for the effect of flow-mediated transport of molecules to the nucleus of the new phase, as well as for the mechanical deformation imparted to the nucleus by the flow field. The competition between flow-induced molecular transport, which accelerates nucleation, and flow-induced nucleus straining, which lowers the nucleation rate by increasing the nucleation energy barrier, gives rise to a marked nonmonotonic dependence of the nucleation rate on the shear rate. The theory predicts an optimal shear rate at which the nucleation rate is one order of magnitude larger than in the absence of flow.

  16. A hydrodynamic model for granular material flows including segregation effects

    Science.gov (United States)

    Gilberg, Dominik; Klar, Axel; Steiner, Konrad

    2017-06-01

    The simulation of granular flows including segregation effects in large industrial processes using particle methods is accurate, but very time-consuming. To overcome the long computation times a macroscopic model is a natural choice. Therefore, we couple a mixture theory based segregation model to a hydrodynamic model of Navier-Stokes-type, describing the flow behavior of the granular material. The granular flow model is a hybrid model derived from kinetic theory and a soil mechanical approach to cover the regime of fast dilute flow, as well as slow dense flow, where the density of the granular material is close to the maximum packing density. Originally, the segregation model has been formulated by Thornton and Gray for idealized avalanches. It is modified and adapted to be in the preferred form for the coupling. In the final coupled model the segregation process depends on the local state of the granular system. On the other hand, the granular system changes as differently mixed regions of the granular material differ i.e. in the packing density. For the modeling process the focus lies on dry granular material flows of two particle types differing only in size but can be easily extended to arbitrary granular mixtures of different particle size and density. To solve the coupled system a finite volume approach is used. To test the model the rotational mixing of small and large particles in a tumbler is simulated.

  17. Characterization of non equilibrium effects on high quality critical flows

    International Nuclear Information System (INIS)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J.

    1995-01-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness

  18. Characterization of non equilibrium effects on high quality critical flows

    Energy Technology Data Exchange (ETDEWEB)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J. [Commissariat a l Energie Atomique, Grenoble (France)] [and others

    1995-09-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness.

  19. Comparison of Y-jet and OIL effervescent atomizers based on internal and external two-phase flow characteristics

    Directory of Open Access Journals (Sweden)

    Mlkvik Marek

    2016-01-01

    Full Text Available Presented paper focuses on spraying of two viscous liquids (μ = 60 and 143 mPa·s by two types of twinfluid atomizers with internal mixing. We compared the well-known Y-jet atomizer with the less known, “outside in liquid” (OIL, configuration of the effervescent atomizer. The required liquid viscosity was achieved by using the water-maltodextrin solutions of different concentrations. Both the liquids were sprayed at two gas inlet pressures (Δp = 0.14 and 0.28 MPa and various gas-to-liquid ratios (GLR = 2.5%, 5%, 10% and 20%. The comparison was focused on four characteristics: liquid flow-rate (for the same working regimes, defined by Δp and GLR, internal flow regimes, Weber numbers of a liquid breakup (We and droplet sizes. A high-speed camera and Malvern Spraytec laser diffraction system were used to obtain necessary experimental data. Comparing the results of our experiments, we can state that for both the liquids the OIL atomizer reached higher liquid flow-rates at corresponding working regimes, it was typical by annular internal flow and higher We in the near-nozzle region at all the working regimes. As a result, it produced considerably smaller droplets than the second tested atomizing device, especially for GLR < 10%.

  20. Comparison of Y-jet and OIL effervescent atomizers based on internal and external two-phase flow characteristics

    Science.gov (United States)

    Mlkvik, Marek; Zaremba, Matous; Jedelsky, Jan; Jicha, Miroslav

    2016-03-01

    Presented paper focuses on spraying of two viscous liquids (μ = 60 and 143 mPa·s) by two types of twinfluid atomizers with internal mixing. We compared the well-known Y-jet atomizer with the less known, "outside in liquid" (OIL), configuration of the effervescent atomizer. The required liquid viscosity was achieved by using the water-maltodextrin solutions of different concentrations. Both the liquids were sprayed at two gas inlet pressures (Δp = 0.14 and 0.28 MPa) and various gas-to-liquid ratios (GLR = 2.5%, 5%, 10% and 20%). The comparison was focused on four characteristics: liquid flow-rate (for the same working regimes, defined by Δp and GLR), internal flow regimes, Weber numbers of a liquid breakup (We) and droplet sizes. A high-speed camera and Malvern Spraytec laser diffraction system were used to obtain necessary experimental data. Comparing the results of our experiments, we can state that for both the liquids the OIL atomizer reached higher liquid flow-rates at corresponding working regimes, it was typical by annular internal flow and higher We in the near-nozzle region at all the working regimes. As a result, it produced considerably smaller droplets than the second tested atomizing device, especially for GLR < 10%.

  1. Pulsatile flow effects on the hemodynamics of intracranial aneurysms.

    Science.gov (United States)

    Le, Trung B; Borazjani, Iman; Sotiropoulos, Fotis

    2010-11-01

    High-resolution numerical simulations are carried out to systematically investigate the effect of the incoming flow waveform on the hemodynamics and wall shear stress patterns of an anatomic sidewall intracranial aneurysm model. Various wave forms are constructed by appropriately scaling a typical human waveform such that the waveform maximum and time-averaged Reynolds numbers, the Womersley number (α), and the pulsatility index (PI) are systematically varied within the human physiologic range. We show that the waveform PI is the key parameter that governs the vortex dynamics across the aneurysm neck and the flow patterns within the dome. At low PI, the flow in the dome is similar to a driven cavity flow and is characterized by a quasi-stationary shear layer that delineates the parent artery flow from the recirculating flow within the dome. At high PI, on the other hand, the flow is dominated by vortex ring formation, transport across the neck, and impingement and breakdown at the distal wall of the aneurysm dome. We further show that the spatial and temporal characteristics of the wall shear stress field on the aneurysm dome are strongly correlated with the vortex dynamics across the neck. We finally argue that the ratio between the characteristic time scale of transport by the mean flow across the neck and the time scale of vortex ring formation can be used to predict for a given sidewall aneurysm model the critical value of the waveform PI for which the hemodynamics will transition from the cavity mode to the vortex ring mode.

  2. Effect of sheared flows on neoclassical tearing modes

    Energy Technology Data Exchange (ETDEWEB)

    Sen, A [Institute for Plasma Research, Bhat, Gandhinagar (India); Chandra, D; Kaw, P [Institute for Plasma Research, Bhat, Gandhinagar (India); Bora, M P [Physics Dept., Gauhati University, Guwahati (India); Kruger, S [Tech-X, Boulder, CO (United States); Ramos, J [Plasma Science and Fusion Center, MIT, Cambridge, MA (United States)

    2005-01-01

    The influence of toroidal sheared equilibrium flows on the nonlinear evolution of classical and neoclassical tearing modes (NTMs) is studied through numerical solutions of a set of reduced generalized MHD equations that include viscous force effects based on neoclassical closures. In general, differential flow is found to have a strong stabilizing influence leading to lower saturated island widths for the classical (m/n = 2/1) mode and reduced growth rates for the (m/n = 3/1) neoclassical mode. Velocity shear on the other hand is seen to make a destabilizing contribution. An analytic model calculation, consisting of a generalized Rutherford island evolution equation that includes shear flow effects is also presented and the numerical results are discussed in the context of this model. (author)

  3. The structure of the stably stratified internal boundary layer in offshore flow over the sea

    Science.gov (United States)

    Garratt, J. R.; Ryan, B. F.

    1989-04-01

    Observations obtained mainly from a research aircraft are presented of the mean and turbulent structure of the stably stratified internal boundary layer (IBL) over the sea formed by warm air advection from land to sea. The potential temperature and humidity fields reveal the vertical extent of the IBL, for fetches out to several hundred of kilometres, geostrophic winds of 20 25 m s-1, and potential temperature differences between undisturbed continental air and the sea surface of 7 to 17 K. The dependence of IBL depth on these external parameters is discussed in the context of the numerical results of Garratt (1987), and some discrepancies are noted. Wind observations show the development of a low-level wind maximum (wind component normal to the coast) and rotation of the wind to smaller cross-isobar flow angles. Potential temperature (θ) profiles within the IBL reveal quite a different structure to that found in the nocturnal boundary layer (NBL) over land. Over the sea, θ profiles have large positive curvature with vertical gradients increasing monotonically with height; this reflects the dominance of turbulent cooling within the layer. The behaviour is consistent with known behaviour in the NBL over land where curvature becomes negative (vertical gradients of θ decreasing with height) as radiative cooling becomes dominant. Turbulent properties are discussed in terms of non-dimensional quantities, normalised by the surface friction velocity, as functions of normalised height using the IBL depth. Vertical profiles of these and the normalised wavelength of the spectral maximum agree well with known results for the stable boundary layer over land (Caughey et al., 1979).

  4. Potential effects of elevated base flow and midsummer spike flow experiments on riparian vegetation along the Green River

    Science.gov (United States)

    Friedman, Jonathan M.

    2018-01-01

    The Upper Colorado River Endangered Fish Recovery Program has requested experimental flow releases from Flaming Gorge Dam for (1) elevated summer base flows to promote larval endangered Colorado pikeminnow, and (2) midsummer spike flows to disadvantage spawning invasive smallmouth bass. This white paper explores the effects of these proposed flow modifications on riparian vegetation and sediment deposition downstream along the Green River. Although modest in magnitude, the elevated base flows and possible associated reductions in magnitude or duration of peak flows would exacerbate a long-term trend of flow stabilization on the Green River that is already leading to proliferation of vegetation including invasive tamarisk along the channel and associated sediment deposition, channel narrowing and channel simplification. Midsummer spike flows could promote establishment of late-flowering plants like tamarisk. Because channel narrowing and simplification threaten persistence and quality of backwater and side channel features needed by endangered fish, the proposed flow modifications could lead to degradation of fish habitat. Channel narrowing and vegetation encroachment could be countered by increases in peak flows or reductions in base flows in some years and by prescription of rapid flow declines following midsummer spike flows. These strategies for reducing vegetation encroachment would need to be balanced with flow

  5. Effects of peatland drainage management on peak flows

    Directory of Open Access Journals (Sweden)

    C. E. Ballard

    2012-07-01

    Full Text Available Open ditch drainage has historically been a common land management practice in upland blanket peats, particularly in the UK. However, peatland drainage is now generally considered to have adverse effects on the upland environment, including increased peak flows. As a result, drain blocking has become a common management strategy in the UK over recent years, although there is only anecdotal evidence to suggest that this might decrease peak flows. The change in the hydrological regime associated with the drainage of blanket peat and the subsequent blocking of drains is poorly understood, therefore a new physics-based model has been developed that allows the exploration of the associated hydrological processes. A series of simulations is used to explore the response of intact, drained and blocked drain sites at field scales. While drainage is generally found to increase peak flows, the effect of drain blocking appears to be dependent on local conditions, sometimes decreasing and sometimes increasing peak flows. Based on insights from these simulations we identify steep smooth drains as those that would experience the greatest reduction in field-scale peak flows if blocked and recommend that future targeted field studies should be focused on examining surface runoff characteristics.

  6. Flow effects on the stability of z-pinches

    International Nuclear Information System (INIS)

    Shumlak, U.; Hartman, C.W.

    1996-01-01

    The effect of an axial flow on the m = 1 kink instability in z-pinches is studied numerically by reducing the linearized ideal MHD equations to a one-dimensional eigenvalue equation for the radial displacement. The derivation of the displacement equation for equilibria with axial flows will be presented. A diffuse z-pinch equilibrium is chosen that is made marginally stable to the m = 0 sausage mode by tailoring the pressure profile. The principle result reveals that a sheared axial flow does stabilize the kink mode when the shear exceeds a threshold value. Additionally, the m = 0 sausage mode is driven from marginal stability into the stable regime which suggests that the equilibrium pressure profile control can be relaxed. Fast z-pinches such as liner implosions are plagued by the Rayleigh-Taylor instability which destroys the liner and disrupts the current path before the liner arrives on axis. A sheared axial flow in a liner may quench the Rayleigh-Taylor instability in the same way that it quenches MHD instabilities in a diffuse z-pinch. Simulation results will be presented showing the effect of a sheared axial flow on the Rayleigh-Taylor instability in a fast liner implosion

  7. Biofilm Effect on Flow Structure over a Permeable Bed

    Science.gov (United States)

    Kazemifar, F.; Blois, G.; Aybar, M.; Perez-Calleja, P.; Nerenberg, R.; Sinha, S.; Hardy, R. J.; Best, J.; Sambrook Smith, G.; Christensen, K. T.

    2017-12-01

    Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces in natural and industrial settings, such as water distribution systems and riverbeds among others. The permeable, heterogeneous, and deformable structure of biofilms can influence mass and momentum transport between the subsurface and freestream. However, this interaction is not fully understood, in part due to technical obstacles impeding quantitative experimental investigations. In this work, the effect of biofilm on flow structure over a permeable bed is studied. Experiments are conducted in a closed water channel equipped with an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent recirculating reactor for biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

  8. Report of the results of the International Clinical Cytometry Society and American Society for Clinical Pathology workload survey of clinical flow cytometry laboratories.

    Science.gov (United States)

    Wolniak, Kristy; Goolsby, Charles; Choi, Sarah; Ali, Asma; Serdy, Nina; Stetler-Stevenson, Maryalice

    2017-11-01

    Thorough review of current workload, staffing, and testing practices in clinical laboratories allows for optimization of laboratory efficiency and quality. This information is largely missing with regard to clinical flow cytometry laboratories. The purpose of this survey is to provide comprehensive, current, and accurate data on testing practices and laboratory staffing in clinical laboratories performing flow cytometric studies. Survey data was collected from flow cytometry laboratories through the ASCP website. Data was collected on the workload during a 1-year time period of full-time and part-time technical and professional (M.D./D.O./Ph.D. or equivalent) flow cytometry employees. Workload was examined as number of specimens and tubes per full time equivalent (FTE) technical and professional staff. Test complexity, test result interpretation, and reporting practices were also evaluated. There were 205 respondent laboratories affiliated predominantly with academic and health system institutions. Overall, 1,132 FTE employees were reported with 29% professional FTE employees and 71% technical. Fifty-one percent of the testing performed was considered high complexity and 49% was low complexity. The average number of tubes per FTE technologist was 1,194 per year and the average number of specimens per FTE professional was 1,659 per year. The flow cytometry reports were predominantly written by pathologists (57%) and were typically written as a separate report (58%). This survey evaluates the overall status of the current practice of clinical flow cytometry and provides a comprehensive dataset as a framework to help laboratory departments, directors, and managers make appropriate, cost-effective staffing decisions. © 2016 International Clinical Cytometry Society. © 2016 International Clinical Cytometry Society.

  9. Effects of Inner Surface Roughness and Asymmetric Pipe Flow on Accuracy of Profile Factor for Ultrasonic Flow Meter

    International Nuclear Information System (INIS)

    Michitsugu Mori; Kenichi Tezuka; Yasushi Takeda

    2006-01-01

    Flow profile factors (PFs), which adjust measurements to real flow rates, also strongly depend on flow profiles. To determine profile factors for actual power plants, manufactures of flowmeters usually conduct factory calibration tests under ambient flow conditions. Indeed, flow measurements with high accuracy for reactor feedwater require them to conduct calibration tests under real conditions, such as liquid conditions and piping layouts. On the contrary, as nuclear power plants are highly aging, readings of flowmeters for reactor feedwater systems drift due to the changes of flow profiles. The causes of those deviations are affected by the change of wall roughness of inner surface of pipings. We have conducted experiments to quantify the effects of flow patterns on the PFs due to pipe roughness and asymmetric flow, and the results of our experiments have shown the effects of elbows and pipe inner roughness, which strongly affect to the creation of the flow patterns. Those changes of flow patterns lead to large errors in measurements with transit time (time-of-flight: TOF) ultrasonic flow meters. In those experiments, changes of pipe roughness result in the changes of PFs with certain errors. Therefore, we must take into account those effects in order to measure the flow rates of feedwater with better accuracy in actual power plants. (authors)

  10. A Fixed Flow is More Effective than Titrated Flow during Bubble Nasal CPAP for Respiratory Distress in Preterm Neonates.

    Science.gov (United States)

    Murki, Srinivas; Das, Ratan Kumar; Sharma, Deepak; Kumar, Praveen

    2015-01-01

    The clinical effects of a pre-fixed flow of air-oxygen versus a flow titrated according to visible bubbling are not well understood. To compare the effects of a fixed flow (5 L/min) and titrated flow (flow just enough to ensure bubbling) at different set pressures on delivered intra-prong pressure, gas exchange and clinical parameters in preterm infants on bubble CPAP for respiratory distress. Preterm infants rate, set pressure, FiO2, SpO2, Silverman retraction score, respiratory rate, abdominal girth, and blood gases were recorded. The delivered intra-prong pressure was measured by an electronic manometer. 69 recordings were made in 54 infants. For each of the set CPAP pressures (4, 5, and 6 cm H2O), the mean delivered pressure with a fixed flow of 5 L/min was higher than that delivered by the titrated flow. During the fixed flow epoch, the delivered pressure was closer to and higher than the set pressure resulting in higher PaO2 and lower PaCO2 as compared to titrated flow epoch. In the titrated flow period, the delivered pressure was consistently lower than the set pressure. In preterm infants on bubble CPAP with set pressures of 4-6 cm H2O, a fixed flow of 5 L/min is more effective than a flow titrated to ensure adequate visible bubbling. It achieves higher delivered pressures, better oxygenation and ventilation.

  11. Ekman effects in a rotating flow over bottom topography

    NARCIS (Netherlands)

    Zavala Sansón, L.; Heijst, van G.J.F.

    2002-01-01

    This paper presents a general two-dimensional model for rotating barotropic flows over topography. The model incorporates in a vorticity–stream function formulation both inviscid topography effects, associated with stretching and squeezing of fluid columns enforced by their motion over variable

  12. The poverty effect of remittance flows: evidence from Georgia

    Czech Academy of Sciences Publication Activity Database

    Uzagalieva, Ainura; Menezes, A. G.

    2009-01-01

    Roč. 21, č. 4 (2009), s. 453-474 ISSN 1463-1377 Institutional research plan: CEZ:AV0Z70850503 Keywords : poverty effects of emmigration * remittance flows * Gergia * computable general equilibrium model Subject RIV: AH - Economics Impact factor: 0.196, year: 2009

  13. Effects of Parallel Channel Interactions, Steam Flow, Liquid Subcool ...

    African Journals Online (AJOL)

    Tests were performed to examine the effects of parallel channel interactions, steam flow, liquid subcool and channel heat addition on the delivery of liquid from the upper plenum into the channels and lower plenum of Boiling Water Nuclear Power Reactors during reflood transients. Early liquid delivery into the channels, ...

  14. Effect of radiation and porosity parameter on hydromagnetic flow ...

    African Journals Online (AJOL)

    The aim of this paper is to study the momentum and the heat transfer characteristics in incompressible electrically conducting boundary layer flow over an exponentially stretching sheet under the effect of magnetic field with thermal radiation through porous medium. The governing boundary layer equations are converted ...

  15. Flow Regime Destabilizing Effect on Fluid elastic Instability of Tube Array Preferentially Flexible to the Flow Direction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kanghee; Shin, Changhwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Olala, Stephen; Mureithi, Njuki [BWC/AECL/NSERC Chair of Fluid-Structure Interaction, Ecole Polytechnique, Montreal (Canada)

    2015-05-15

    U bend region of operating SG is excited by the inclined cross flow due to the gradual change of hydraulic resistance force. The effect of tube array's flexibility direction on FEI is investigated by Khalvatti for rotated triangular tube in single phase (air) cross flow. He showed that FEI strongly depend on the flexibility angle. Reducing bundle flexibility to the flow direction ranging from 90 (out-of-flow direction) to 0 (in-flow direction) degree has a nonlinearly-varying stabilizing effect. Joly studies the same problem under high void fraction in two phase cross flow over 70 % to 90 %. With the Joly's experimental work, there is oddly low-valued Conner's constant in case of higher degree of angle of attack. This gives the motivation to our experimental study for fluid elastic instability of tube array in two phase cross flow. As the flow rate goes up, tube response was measured for each steady state flow condition by the strain gauge. Damping, peak frequency, and the critical velocity were estimated from the response spectrum. It seems that the flow regime for high void fraction can destabilize tube array with preferential flexibility over 60 degree. Because an intermittent flow is inherently unstable compared to the uniform bubbly flow, thus out-of-flow motion of tubes can be more fragile to the unstably rising intermittent flow. From the visual inspection, lateral tube motion seems to block the flow path periodically. Enlarged bubble in an intermittent flow regime can be squeezed-up at the flow gap between tubes.

  16. Three-dimensional measurement and visualization of internal flow of a moving droplet using confocal micro-PIV.

    Science.gov (United States)

    Kinoshita, Haruyuki; Kaneda, Shohei; Fujii, Teruo; Oshima, Marie

    2007-03-01

    This paper presents a micro-flow diagnostic technique, 'high-speed confocal micro-particle image velocimetry (PIV)', and its application to the internal flow measurement of a droplet passing through a microchannel. A confocal micro-PIV system has been successfully constructed wherein a high-speed confocal scanner is combined with the conventional micro-PIV technique. The confocal micro-PIV system enables us to obtain a sequence of sharp and high-contrast cross-sectional particle images at 2000 frames s(-1). This study investigates the confocal depth, which is a significant parameter to determine the out-of-plane measurement resolution in confocal micro-PIV. Using the present confocal micro-PIV system, we can measure velocity distributions of micro-flows in a 228 microm x 171 microm region with a confocal depth of 1.88 microm. We also propose a three-dimensional velocity measurement method based on the confocal micro-PIV and the equation of continuity. This method enables us to measure three velocity components in a three-dimensional domain of micro flows. The confocal micro-PIV system is applied to the internal flow measurement of a droplet. We have measured three-dimensional distributions of three-component velocities of a droplet traveling in a 100 microm (width) x 58 microm (depth) channel. A volumetric velocity distribution inside a droplet is obtained by the confocal micro-PIV and the three-dimensional flow structure inside the droplet is investigated. The measurement results suggest that a three-dimensional and complex circulating flow is formed inside the droplet.

  17. Scientists' internal models of the greenhouse effect

    Science.gov (United States)

    Libarkin, J. C.; Miller, H.; Thomas, S. R.

    2013-12-01

    A prior study utilized exploratory factor analysis to identify models underlying drawings of the greenhouse effect made by entering university freshmen. This analysis identified four archetype models of the greenhouse effect that appear within the college enrolling population. The current study collected drawings made by 144 geoscientists, from undergraduate geoscience majors through professionals. These participants scored highly on a standardized assessment of climate change understanding and expressed confidence in their understanding; many also indicated that they teach climate change in their courses. Although geoscientists held slightly more sophisticated greenhouse effect models than entering freshmen, very few held complete, explanatory models. As with freshmen, many scientists (44%) depict greenhouse gases in a layer in the atmosphere; 52% of participants depicted this or another layer as a physical barrier to escaping energy. In addition, 32% of participants indicated that incoming light from the Sun remains unchanged at Earth's surface, in alignment with a common model held by students. Finally, 3-20% of scientists depicted physical greenhouses, ozone, or holes in the atmosphere, all of which correspond to non-explanatory models commonly seen within students and represented in popular literature. For many scientists, incomplete models of the greenhouse effect are clearly enough to allow for reasoning about climate change. These data suggest that: 1) better representations about interdisciplinary concepts, such as the greenhouse effect, are needed for both scientist and public understanding; and 2) the scientific community needs to carefully consider how much understanding of a model is needed before necessary reasoning can occur.

  18. Measurement of cerebral blood flow by single photon emission computed tomography in cases of internal carotid artery occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Sunada, Ichiro [Osaka City Univ. (Japan). Faculty of Medicine

    1989-06-01

    Cerebral blood flow (CBF) was measured with {sup 133}xenon inhalation and single photon emission computed tomography in 33 cases of internal carotid artery occlusion, in the resting state and 25 minutes after acetazolamide administration. The patient population consisted of 24 males and nine females with a mean age of 57 years, who presented with transient ischemic attacks or stroke. Acetazolamide inhibits carbonic anhydrase, and CBF increases as a result of dilatation of cerebral arteries due to CO{sub 2} accumulation. The mean CBF was 46 ml/100 g/min on the affected hemisphere and 56 ml/100 g/min on the unaffected hemisphere. The mean CBF value obtained by the same method in 10 normal volunteers was 55 ml/100 g/min. The average increase in CBF after acetazolamide administration was 9% on the affected side and 17% on the unaffected side. The average increase in 10 normal volunteers was 32%. The reduced cerebral arterial reactivity to acetazolamide administration was bilateral in the patient group, suggesting that the cerebral arteries were dilated so as to maintain normal CBF. Extra-intracranial (EC-IC) bypass surgery was performed in nine patients. Preoperatively, the mean CBF was 48 ml/100 g/min on the affected side and 57 ml/100 g/min on the unaffected side. With postoperative acetazolamide administration, the percent increase in CBF rose from 13% to 22% on the affected side and from 17% to 23% on the unaffected side. The bilateral change toward normal in cerebral arterial reactivity to acetazolamide indicates that the dilated cerebral arteries returned to normal after EC-IC bypass surgery. This suggests that bypass surgery is effective in patients with internal carotid artery occlusion in whom ischemia is caused only by hemodynamic factors, and that measurement of CBF via acetazolamide loading is useful in identifying appropriate candidates for bypass surgery.

  19. Three-dimensional analysis of internal flow characteristics in the injection nozzle tip of direct-injection diesel engines; Sanjigen suchi kaiseki ni yoru DI diesel kikan no nenryo funsha nozzle nai ryudo tokusei no kaimei

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, H; Matsui, Y; Kimura, S [Nissan Motor Co. Ltd. Tokyo (Japan)

    1997-10-01

    To reduce the exhaust emissions and fuel consumption of direct-injection diesel engines, it is essential to optimize the fuel injection equipment closely related to combustion and emission characteristics. In this study, three-dimensional computation has been applied to investigate the effects of the injection nozzle specifications (e.g., sac volume, round shape at the inlet of the nozzle hole) and needle tip deviation on internal flow characteristics. The computational results revealed that the effects of the nozzle specifications and needle tip deviation with a smaller needle lift on internal flow characteristics and a general approach to optimize the injection nozzle specifications were obtained. 3 refs., 10 figs., 1 tab.

  20. Flow development through HP & LP turbines, Part II: Effects of the hub endwall secondary sealing air flow on the turbine's mainstream flow

    Science.gov (United States)

    Hu, Jialin; Du, Qiang; Liu, Jun; Wang, Pei; Liu, Guang; Liu, Hongrui; Du, Meimei

    2017-08-01

    Although many literatures have been focused on the underneath flow and loss mechanism, very few experiments and simulations have been done under the engines' representative working conditions or considering the real cavity structure as a whole. This paper aims at realizing the goal of design of efficient turbine and scrutinizing the velocity distribution in the vicinity of the rim seal. With the aid of numerical method, a numerical model describing the flow pattern both in the purge flow spot and within the mainstream flow path is established, fluid migration and its accompanied flow mechanism within the realistic cavity structure (with rim seal structure and considering mainstream & secondary air flow's interaction) is used to evaluate both the flow pattern and the underneath flow mechanism within the inward rotating cavity. Meanwhile, the underneath flow and loss mechanism are also studied in the current paper. The computational results show that the sealing air flow's ingestion and ejection are highly interwound with each other in both upstream and downstream flow of the rim seal. Both the down-stream blades' potential effects as well as the upstream blades' wake trajectory can bring about the ingestion of the hot gas flow within the cavity, abrupt increase of the static pressure is believed to be the main reason. Also, the results indicate that sealing air flow ejected through the rear cavity will cause unexpected loss near the outlet section of the blades in the downstream of the HP rotor passages.

  1. Nuclear dynamics with the (finite range) Gogny force: flow effects

    International Nuclear Information System (INIS)

    Sebille, F.; Royer, G.; Schuck, P.; Gregoire, C.

    1988-01-01

    We introduce for the first time the effective finite range interaction of Gogny in the semi-classical description of heavy ion reactions based on the Landau-Vlasov equation. The characteristics of the flow for heavy ion collisions are studied as functions of the incident energy, the impact parameter and the mass number. The momentum dependence in the mean field together with the non linearities in the collision kernel decrease the flow in contradiction with other calculations; the origins of this discrepancy are studied in details

  2. Geometrical effects on the airfoil flow separation and transition

    KAUST Repository

    Zhang, Wei

    2015-04-25

    We present results from direct numerical simulations (DNS) of incompressible flow over two airfoils, NACA-4412 and NACA-0012-64, to investigate the effects of the airfoil geometry on the flow separation and transition patterns at Re=104 and 10 degrees incidence. The two chosen airfoils are geometrically similar except for maximum camber (respectively 4%C and 0 with C the chord length), which results in a larger projection area with respect to the incoming flow for the NACA-4412 airfoil, and a larger leeward surface curvature at the leading edge for the NACA-0012-64 airfoil. The governing equations are discretized using an energy conservative fourth-order spatial discretization scheme. An assessment on the two-point correlation indicates that a spanwise domain size of 0.8C is sufficiently large for the present simulations. We discuss flow separation at the airfoil leading edge, transition of the separated shear layer to three-dimensional flow and subsequently to turbulence. Numerical results reveal a stronger adverse pressure gradient field in the leading edge region of the NACA-0012-64 airfoil due to the rapidly varying surface curvature. As a result, the flow experiences detachment at x/C=0.08, and the separated shear layer transition via Kelvin-Helmholtz mechanism occurs at x/C=0.29 with fully developed turbulent flow around x/C=0.80. These flow development phases are delayed to occur at much downstream positions, respectively, observed around x/C=0.25, 0.71 and 1.15 for the NACA-4412 airfoil. The turbulent intensity, measured by the turbulent fluctuations and turbulent Reynolds stresses, are much larger for NACA-0012-64 from the transition onset until the airfoil trailing edge, while turbulence develops significantly downstream of the trailing edge for the NACA-4412 airfoil. For both airfoils, our DNS results indicate that the mean Reynolds stress u\\'u\\'/U02 reaches its maximum value at a distance from the surface approximately equal to the displacement

  3. Effects of alloy composition and flow condition on the flow accelerated corrosion in neutral water condition

    International Nuclear Information System (INIS)

    Satoh, Tomonori; Ugachi, Hirokazu; Tsukada, Takashi; Uchida, Shunsuke

    2008-01-01

    The major mechanism of Flow accelerated corrosion (FAC) is the dissolution of the protective oxide on carbon steel, which is enhanced by mass transfer and erosion under high flow velocity conditions. In this study, the effects of alloy composition and flow velocity on FAC of carbon steel were evaluated by measuring FAC rate of tube type carbon steel specimens in the neutral water condition at 150degC. Obtained results are summarized in follows. 1) High FAC rate was depended upon the v 1.2 in the tube type specimen made of the standard alloy. 2) FAC was mitigated for the carbon steel with more than 0.03% of Cr content. 3) FAC rate decreased as Ni content increased in more than 0.1% of Ni content. 4) The difference in chemical composition of oxide film between Ni added carbon steel and Cr added one was confirmed. The hematite rich oxide was observed for Ni added carbon steel. 5) The effects of Cu on FAC rate was not observed up to 0.1% of Cu content. (author)

  4. CFD simulations of flow erosion and flow-induced deformation of needle valve: Effects of operation, structure and fluid parameters

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hongjun, E-mail: ticky863@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China); State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, Sichuan (China); Pan, Qian; Zhang, Wenli; Feng, Guang; Li, Xue [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China)

    2014-07-01

    Highlights: • A combined FSI–CFD and DPM computational method is used to investigate flow erosion and deformation of needle valve. • The numerical model is validated with the comparison of measured and predicted erosion rate. • Effects of operation, structure and fluid parameters on flow erosion and flow-induced deformation are discussed. • Particle diameter has the most significant effect on flow erosion. • Inlet rate has the most obvious effect on flow-induced deformation. - Abstract: A three-dimensional fluid–structure interaction (FSI) computational model coupling with a combined continuum and discrete model has been used to predict the flow erosion rate and flow-induced deformation of needle valve. Comparisons with measured data demonstrate good agreement with the predictions of erosion rate. The flow field distribution of gas-particle flow and the erosion rate and deformation of valve core are captured under different operating and structural conditions with different fluid parameters. The effects of inlet velocity, valve opening and inlet valve channel size, particle concentration, particle diameter and particle phase components are discussed in detail. The results indicate that valve tip has the most severe erosion and deformation, and flow field, erosion rate and deformation of valve are all sensitive to inlet condition changes, structural changes and fluid properties changes. The effect of particle diameter on erosion is the most significant, while the influence of inlet rate on deformation is the greatest one.

  5. An Evaluation of GuttaFlow2 in Filling Artificial Internal Resorption Cavities: An in vitro Study.

    Science.gov (United States)

    Mohammad, Yara; Alafif, Hisham; Hajeer, Mohammad; Yassin, Oula

    2016-06-01

    Obturation of root canal with internal resorption represents a major challenge in Endodontics. In spite of that, usual obturation techniques are often employed without considering the best technique to solve this problem. The goal of this study was to investigate the ability of GuttaFlow2 in filling artificial internal resorption cavities. The study sample included 36 human upper central incisors that were prepared using Protaper system (F4). Internal resorption cavities were prepared by cutting each tooth at 7 mm from the apex and preparing hemispherical cavities on both the sides and then re-attaching them. The sample was randomly separated into three groups (n = 12 in each group). In the first group, thermal injection technique (Obtura II) was employed and served as the control group. In the second group, injection of cold free-flow obturation technique with a master cone (GF2-C) was employed, whereas in the third group injection of cold free-flow obturation without a master cone (GF2) was followed. The teeth were re-cut at the same level as before and examined under a stereomicroscope. Subsequently, the captured images were transferred to AutoCAD program to measure the percentage of total filling "TF," gutta-percha "G," sealer "S," and voids "V" out of the total surface of the cross sections. All materials showed high filling properties in terms of "total filling," ranging from 99.17% (for Obtura II) to 99.72% (for GF2-C). Regarding gutta-percha percentages of filling, they ranged from 83.15 to 83.93%, whereas those for the sealer ranged from 5.71 to 15.24%. GuttaFlow2 group with a master cone appeared to give the best results despite the insignificant differences among the three groups. The GuttaFlow2 with a master cone technique seemed to be a promising filling material and gave results similar to those observed with Obtura II. It is recommended for use to obturate internal resorption cavities in clinical practice due to its good adaptability to root canal

  6. Effect of Cervical Siphon of External and Internal Carotid Arteries.

    Science.gov (United States)

    Singh, Rajani; Tubbs, Richard Shane

    2017-10-01

    Variant courses, configuration, and branching pattern of the external and internal carotid arteries, especially when curved in S-shape, are important for hemodynamic changes and clinical implications. Therefore, the aim of the study is to report abnormal cervical siphons observed in external and internal carotid arteries to explore clinical significance by review of literature and hemodynamic changes theoretically.The right common carotid artery bifurcated into external and internal carotid arteries at the level of the upper border of thyroid cartilage in a 70-year-old female cadaver. After bifurcation, the external carotid artery underwent severe tortuosity coursing through 5 bends at points A, B, C, D, and E from its origin to termination and 2 bends at A' and B' in internal carotid artery in the cervical region. The angles between inflow and out flow of the blood at the bends were measured and the change in velocity at each bend was computed for both arteries. Hemodynamic changes were calculated, compared and relevant clinical complications were theoretically correlated.The angles of 20°, 30°, 51°, 52°, 60°, and 28°, 48° were formed by 5 bends of external and 2 bends of internal carotid arteries, respectively. The curved courses of these arteries caused reduction in velocity/stasis, turbulence, and low shear stress. Such kinks might cause stroke, ischemia and mistaken for tumors and abscess in imagery leading to or otherwise producing iatrogenic repercussions. This study will be useful for anatomists, clinicians, and radiologists.

  7. Flow effects on benthic stream invertebrates and ecological processes

    Science.gov (United States)

    Koprivsek, Maja; Brilly, Mitja

    2010-05-01

    Flow is the main abiotic factor in the streams. Flow affects the organisms in many direct and indirect ways. The organisms are directly affected by various hydrodynamic forces and mass transfer processes like drag forces, drift, shear stress, food and gases supply and washing metabolites away. Indirect effects on the organisms are determining and distribution of the particle size and structure of the substrate and determining the morphology of riverbeds. Flow does not affect only on individual organism, but also on many ecological effects. To expose just the most important: dispersal of the organisms, habitat use, resource acquisition, competition and predator-prey interactions. Stream invertebrates are adapted to the various flow conditions in many kinds of way. Some of them are avoiding the high flow with living in a hyporeic zone, while the others are adapted to flow with physical adaptations (the way of feeding, respiration, osmoregulation and resistance to draught), morphological adaptations (dorsoventrally flattened shape of organism, streamlined shape of organism, heterogeneous suckers, silk, claws, swimming hair, bristles and ballast gravel) or with behaviour. As the flow characteristics in a particular stream vary over a broad range of space and time scales, it is necessary to measure accurately the velocity in places where the organisms are present to determine the actual impact of flow on aquatic organisms. By measuring the mean flow at individual vertical in a single cross-section, we cannot get any information about the velocity situation close to the bottom of the riverbed where the stream invertebrates are living. Just measuring the velocity near the bottom is a major problem, as technologies for measuring the velocity and flow of natural watercourses is not adapted to measure so close to the bottom. New researches in the last two decades has shown that the thickness of laminar border layer of stones in the stream is only a few 100 micrometers, what

  8. Financial modeling in medicine: cash flow, basic metrics, the time value of money, discount rates, and internal rate of return.

    Science.gov (United States)

    Lexa, Frank James; Berlin, Jonathan W

    2005-03-01

    In this article, the authors cover tools for financial modeling. Commonly used time lines and cash flow diagrams are discussed. Commonly used but limited terms such as payback and breakeven are introduced. The important topics of the time value of money and discount rates are introduced to lay the foundation for their use in modeling and in more advanced metrics such as the internal rate of return. Finally, the authors broach the more sophisticated topic of net present value.

  9. Flow visualization of forced and natural convection in internal cavities. 1998 annual progress report

    International Nuclear Information System (INIS)

    Brodkey, R.S.; Clarksean, R.; Crepeau, J.C.; Guezennec, Y.G.; McEligot, D.M.

    1998-01-01

    'The objective of this research program is to understand the fluid physics when corroded spent nuclear fuel (SNF) elements are passivated by injecting treatment gases into a storage canister. By developing a reliable predictive technique for the energy, mass, and momentum transfer in the presence of surface reactions, transfer and storage systems can be efficiently and safely designed. The objective will be reached by using innovative flow visualization techniques and experimental measurements of the flow field to support computational models. This report summarizes work completed after eight months of a three-year, collaborative project. A generic idealization of a combined drying and passivation approach has been defined, which represents a section of a vertical canister with baskets of SNF elements. This simulation includes flow phenomena that occur in canisters for high- and/or low-enrichment fuels. A steady flow of the passivation fluid is introduced at the bottom of the canister via a central tube from the top. Fluid flows through an array of holes in the perforated basket support plate then around the simulated elements and out the top. Dimensions and flow rates for the idealized situation correspond to those for typical drying canisters. Approximate calculations have identified the ranges of values of flow parameters needed to determine the flow regimes occurring in practice.'

  10. The Determinants of International Student Mobility Flows: An Empirical Study on the Erasmus Programme

    Science.gov (United States)

    Rodriguez Gonzalez, Carlos; Bustillo Mesanza, Ricardo; Mariel, Petr

    2011-01-01

    The Erasmus Programme for higher education students is supposed to play an important socio-economic role within Europe. Erasmus student mobility flows have reached a relevant level of two million since 1987, boosted in recent years by the enlargement of the programme to eastern countries. Thereafter, it seems that flows have staggered. In this…

  11. Preparing a Minimum Information about a Flow Cytometry Experiment (MIFlowCyt) compliant manuscript using the International Society for Advancement of Cytometry (ISAC) FCS file repository (FlowRepository.org).

    Science.gov (United States)

    Spidlen, Josef; Breuer, Karin; Brinkman, Ryan

    2012-07-01

    FlowRepository.org is a Web-based flow cytometry data repository provided by the International Society for Advancement of Cytometry (ISAC). It supports storage, annotation, analysis, and sharing of flow cytometry datasets. A fundamental tenet of scientific research is that published results should be open to independent validation and refutation. With FlowRepository, researchers can annotate their datasets in compliance with the Minimum Information about a Flow Cytometry Experiment (MIFlowCyt) standard, thus greatly facilitating third-party interpretation of their data. In this unit, we will mainly focus on the deposition, sharing, and annotation of flow cytometry data.

  12. The Effect of International Trade on Rule of Law

    Directory of Open Access Journals (Sweden)

    Junsok Yang

    2013-03-01

    Full Text Available In this paper, we look at the relationship between international trade and the rule of law, using the World Justice Project Rule of Law Index, which include index figures on human rights, limits on government powers, transparency and regulatory efficiency. Based on regression analyses using the rule of law index figures and international trade figures (merchandise trade, service trade, exports and importsIn this paper, we look at the relationship between international trade and the rule of law, using the World Justice Project Rule of Law Index, which include index figures on human rights, limits on government powers, transparency and regulatory efficiency. Based on regression analyses using the rule of law index figures and international trade figures (merchandise trade, service trade, exports and imports as percentage of GDP, international trade and basic human rights seem to have little relationship; but trade has a close positive relationship with strong order and security. Somewhat surprisingly, regulatory transparency and effective implementation seems to have little or no effect on international trade and vice versa. International trade shows a clear positive relationship with the country’s criminal justice system, but the relationship with the civil justice system is not as clear as such. For regulatory implementation and civil justice, services trade positively affect these institutions, but these institutions in turn affect exports more strongly than services trade. Finally, the effect of trade on rule of law is stronger on a medium to long term (10-20 year time horizon.

  13. Heat transfer characteristics for evaporation of R417A flowing inside horizontal smooth and internally grooved tubes

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoyan, Zhang [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China); School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China)], E-mail: gqzxy@sohu.com; Xingqun, Zhang; Yunguang, Chen; Xiuling, Yuan [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-06-15

    The experimental study on evaporation heat transfer of R417A (R125/R134a/R600) flowing inside horizontal smooth and two internally grooved tubes with different geometrical parameters was conducted with the mass flow rate range from 176 to 344 kg m{sup -2} s{sup -1}, heat flux from 11 to 32 kW m{sup -2}, evaporation temperature from 0 to 5.5 deg. C and vapor quality from 0.2 to 1. Based on the experimental results, the mechanism and role of the mass flow rate, heat flux, vapor quality and enhanced surface influencing the evaporation heat transfer coefficients were analyzed and discussed. In comparison to R22, the evaporation heat transfer coefficients for R417A were lower and much lower in the internally grooved tubes than in the smooth tube. The present experimental results are also compared with the existing correlations, and the modified Kattan model is found to be in much better agreement with the experimental results than the Kattan model. The Koyama and Wellsandt microfin models all tend to over predict the evaporation heat transfer coefficients rather strongly for R417A inside internally grooved tubes.

  14. Heat transfer characteristics for evaporation of R417A flowing inside horizontal smooth and internally grooved tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoyan [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China); School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China); Zhang, Xingqun; Chen, Yunguang; Yuan, Xiuling [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-06-15

    The experimental study on evaporation heat transfer of R417A (R125/R134a/R600) flowing inside horizontal smooth and two internally grooved tubes with different geometrical parameters was conducted with the mass flow rate range from 176 to 344 kg m{sup -2} s{sup -1}, heat flux from 11 to 32 kW m{sup -2}, evaporation temperature from 0 to 5.5{sup o}C and vapor quality from 0.2 to 1. Based on the experimental results, the mechanism and role of the mass flow rate, heat flux, vapor quality and enhanced surface influencing the evaporation heat transfer coefficients were analyzed and discussed. In comparison to R22, the evaporation heat transfer coefficients for R417A were lower and much lower in the internally grooved tubes than in the smooth tube. The present experimental results are also compared with the existing correlations, and the modified Kattan model is found to be in much better agreement with the experimental results than the Kattan model. The Koyama and Wellsandt microfin models all tend to over predict the evaporation heat transfer coefficients rather strongly for R417A inside internally grooved tubes. (author)

  15. Heat transfer characteristics for evaporation of R417A flowing inside horizontal smooth and internally grooved tubes

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Zhang Xingqun; Chen Yunguang; Yuan Xiuling

    2008-01-01

    The experimental study on evaporation heat transfer of R417A (R125/R134a/R600) flowing inside horizontal smooth and two internally grooved tubes with different geometrical parameters was conducted with the mass flow rate range from 176 to 344 kg m -2 s -1 , heat flux from 11 to 32 kW m -2 , evaporation temperature from 0 to 5.5 deg. C and vapor quality from 0.2 to 1. Based on the experimental results, the mechanism and role of the mass flow rate, heat flux, vapor quality and enhanced surface influencing the evaporation heat transfer coefficients were analyzed and discussed. In comparison to R22, the evaporation heat transfer coefficients for R417A were lower and much lower in the internally grooved tubes than in the smooth tube. The present experimental results are also compared with the existing correlations, and the modified Kattan model is found to be in much better agreement with the experimental results than the Kattan model. The Koyama and Wellsandt microfin models all tend to over predict the evaporation heat transfer coefficients rather strongly for R417A inside internally grooved tubes

  16. Performance Assessment of Turbulence Models for the Prediction of the Reactor Internal Flow in the Scale-down APR+

    International Nuclear Information System (INIS)

    Lee, Gonghee; Bang, Youngseok; Woo, Swengwoong; Kim, Dohyeong; Kang, Minku

    2013-01-01

    The types of errors in CFD simulation can be divided into the two main categories: numerical errors and model errors. Turbulence model is one of the important sources for model errors. In this study, in order to assess the prediction performance of Reynolds-averaged Navier-Stokes (RANS)-based two equations turbulence models for the analysis of flow distribution inside a 1/5 scale-down APR+, the simulation was conducted with the commercial CFD software, ANSYS CFX V. 14. In this study, in order to assess the prediction performance of turbulence models for the analysis of flow distribution inside a 1/5 scale-down APR+, the simulation was conducted with the commercial CFD software, ANSYS CFX V. 14. Both standard k-ε model and SST model predicted the similar flow pattern inside reactor. Therefore it was concluded that the prediction performance of both turbulence models was nearly same. Complex thermal-hydraulic characteristics exist inside reactor because the reactor internals consist of fuel assembly, control rod assembly, and the internal structures. Either flow distribution test for the scale-down reactor model or computational fluid dynamics (CFD) simulation have been conducted to understand these complex thermal-hydraulic features inside reactor

  17. Imaging flow cytometry assays for quantifying pigment grade titanium dioxide particle internalization and interactions with immune cells in whole blood.

    Science.gov (United States)

    Hewitt, Rachel E; Vis, Bradley; Pele, Laetitia C; Faria, Nuno; Powell, Jonathan J

    2017-10-01

    Pigment grade titanium dioxide is composed of sub-micron sized particles, including a nanofraction, and is widely utilized in food, cosmetic, pharmaceutical, and biomedical industries. Oral exposure to pigment grade titanium dioxide results in at least some material entering the circulation in humans, although subsequent interactions with blood immune cells are unknown. Pigment grade titanium dioxide is employed for its strong light scattering properties, and this work exploited that attribute to determine whether single cell-particle associations could be determined in immune cells of human whole blood at "real life" concentrations. In vitro assays, initially using isolated peripheral blood mononuclear cells, identified titanium dioxide associated with the surface of, and within, immune cells by darkfield reflectance in imaging flow cytometry. This was confirmed at the population level by side scatter measurements using conventional flow cytometry. Next, it was demonstrated that imaging flow cytometry could quantify titanium dioxide particle-bearing cells, within the immune cell populations of fresh whole blood, down to titanium dioxide levels of 10 parts per billion, which is in the range anticipated for human blood following titanium dioxide ingestion. Moreover, surface association and internal localization of titanium dioxide particles could be discriminated in the assays. Overall, results showed that in addition to the anticipated activity of blood monocytes internalizing titanium dioxide particles, neutrophil internalization and cell membrane adhesion also occurred, the latter for both phagocytic and nonphagocytic cell types. What happens in vivo and whether this contributes to activation of one or more of these different cells types in blood merits further attention. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

  18. Investigating the effective factors on management internal controls applying

    Directory of Open Access Journals (Sweden)

    Ahmad Ahmadkhani

    2012-08-01

    Full Text Available Information technology plays an important role on increasing internal control in many organizations. In this paper, we present an empirical study to measure the impact of information technology, hiring high quality skilled management team, using high quality standards and increasing employees' awareness on managing internal control. The survey uses a questionnaire based on Likert scale and distributes among the people who work in either administration or financial sectors of governmental agencies in province of Zanjan, Iran. The results of the study indicate that the implementation of information technology positively influences management team to control their system, more effectively, using more skilled and specialized managers positively influences management internal control, an organization with suitable standard positively influences management internal control and increasing employees' awareness positively influences management internal control.

  19. Effect of finite cavity width on flow oscillation in a low-Mach-number cavity flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ke; Naguib, Ahmed M. [Michigan State University, East Lansing, MI (United States)

    2011-11-15

    The current study is focused on examining the effect of the cavity width and side walls on the self-sustained oscillation in a low Mach number cavity flow with a turbulent boundary layer at separation. An axisymmetric cavity geometry is employed in order to provide a reference condition that is free from any side-wall influence, which is not possible to obtain with a rectangular cavity. The cavity could then be partially filled to form finite-width geometry. The unsteady surface pressure is measured using microphone arrays that are deployed on the cavity floor along the streamwise direction and on the downstream wall along the azimuthal direction. In addition, velocity measurements using two-component Laser Doppler Anemometer are performed simultaneously with the array measurements in different azimuthal planes. The compiled data sets are used to investigate the evolution of the coherent structures generating the pressure oscillation in the cavity using linear stochastic estimation of the velocity field based on the wall-pressure signature on the cavity end wall. The results lead to the discovery of pronounced harmonic pressure oscillations near the cavity's side walls. These oscillations, which are absent in the axisymmetric cavity, are linked to the establishment of a secondary mean streamwise circulating flow pattern near the side walls and the interaction of this secondary flow with the shear layer above the cavity. (orig.)

  20. Cerebrospinal fluid flow waveforms: effect of altered cranial venous outflow. A phase-contrast MR flow imaging study

    International Nuclear Information System (INIS)

    Bhadelia, R.A.; Wolpert, S.M.

    1998-01-01

    Our purpose was to assess the effect of alterations in the cranial venous outflow on cerebrospinal fluid (CSF) flow waveforms using phase-contrast MRI. Thirteen healthy subjects were assessed for CSF flow and cerebral vascular flow at the C2-3 level, both before and after jugular venous compression (JVC). The flow waveforms were assessed both as an aggregate, and after dividing subjects in two groups based on percent jugular venous flow (PJVF) i. e. jugular outflow expressed as percent of cerebral arterial inflow. Group 1: 7 subjects with PJVF more than and including median (predominantly jugular outflow); Group 2: 6 subjects with PJVF less than median (predominantly extra-jugular outflow). CSF waveforms: JVC produced rounding of contours and flattening of dicrotic waves, with the effect being greater in group 1 than group 2. In group 1, systolic upslopes of the waveforms increased. No significant aggregate amplitude changes were noted; amplidutes increased in group 1 (P = 0.001), and decreased in group 2 (P = 0.03). Temporal interval to the maximum CSF systolic flow significantly increased in group 1. Vascular flow: Arterial flow significantly decreased in group 1. Jugular flow significantly decreased in both groups. The results suggest that CSF flow waveforms are sensitive to alterations in the cranial venous outflow. Changes in group 1 are most likely because of an elevation in intracranial pressure. Analysis of CSF flow waveforms appears a promising noninvasive tool for assessment of cranial compartment. (orig.)

  1. Preferential flow through intact soil cores: Effects of matrix head

    Energy Technology Data Exchange (ETDEWEB)

    Langner, H.W.; Gaber, H.M.; Wraith, J.M.; Huwe, B.; Inskeep, W.P.

    1999-12-01

    Continuous soil pores may act as pathways for preferential flow depending on their size and water status (filled or drained), the latter being largely controlled by the soil matrix head (h). The literature contains a wide range of proposed minimal pore sizes that may contribute to preferential flow. The objective of this study was to examine the relationship between h (and corresponding pore sizes) and preferential solute transport in a naturally structured soil. Tracer ({sup 3}H{sub 2}O and pentafluorobenzoic acid, [PFBA]) miscible displacement experiments were performed at several h values in intact soil cores (15-cm diameter, 30-cm length) using an apparatus especially suited to maintain constant h while collecting large effluent volumes. To test for the occurrence of preferential flow, observed breakthrough curves (BTCs) were evaluated for physical nonequilibrium (PNE) using a comparison between fitted local equilibrium (PNE) and PNE models. Fitting results of the observed BTCs indicated absence of PNE in all solute transport experiments at h {le} {minus}10 cm. Experiments at h {ge} {minus}5 cm consistently exhibited PNE conditions, indicating the presence of preferential flow. These results suggest that soil pores with effective radii of 150 {micro}m and smaller (water-filled at h = {minus}10 cm) do not contribute to preferential flow. Observed pore water velocities were not indicative of the presence or absence of preferential flow conditions. Continuous measurements of soil water content ({theta}) using time domain reflectometry (TDR) revealed that at h = {minus}10 cm, <2% of the soil volume had drained.

  2. Heat Transfer Computations of Internal Duct Flows With Combined Hydraulic and Thermal Developing Length

    Science.gov (United States)

    Wang, C. R.; Towne, C. E.; Hippensteele, S. A.; Poinsatte, P. E.

    1997-01-01

    This study investigated the Navier-Stokes computations of the surface heat transfer coefficients of a transition duct flow. A transition duct from an axisymmetric cross section to a non-axisymmetric cross section, is usually used to connect the turbine exit to the nozzle. As the gas turbine inlet temperature increases, the transition duct is subjected to the high temperature at the gas turbine exit. The transition duct flow has combined development of hydraulic and thermal entry length. The design of the transition duct required accurate surface heat transfer coefficients. The Navier-Stokes computational method could be used to predict the surface heat transfer coefficients of a transition duct flow. The Proteus three-dimensional Navier-Stokes numerical computational code was used in this study. The code was first studied for the computations of the turbulent developing flow properties within a circular duct and a square duct. The code was then used to compute the turbulent flow properties of a transition duct flow. The computational results of the surface pressure, the skin friction factor, and the surface heat transfer coefficient were described and compared with their values obtained from theoretical analyses or experiments. The comparison showed that the Navier-Stokes computation could predict approximately the surface heat transfer coefficients of a transition duct flow.

  3. Effects of flow gradients on directional radiation of human voice.

    Science.gov (United States)

    Pulkki, Ville; Lähivaara, Timo; Huhtakallio, Ilkka

    2018-02-01

    In voice communication in windy outdoor conditions, complex velocity gradients appear in the flow field around the source, the receiver, and also in the atmosphere. It is commonly known that voice emanates stronger towards the downstream direction when compared with the upstream direction. In literature, the atmospheric effects are used to explain the stronger emanation in the downstream direction. This work shows that the wind also has an effect to the directivity of voice also favouring the downstream direction. The effect is addressed by measurements and simulations. Laboratory measurements are conducted by using a large pendulum with a loudspeaker mimicking the human head, whereas practical measurements utilizing the human voice are realized by placing a subject through the roof window of a moving car. The measurements and a simulation indicate congruent results in the speech frequency range: When the source faces the downstream direction, stronger radiation coinciding with the wind direction is observed, and when it faces the upstream direction, radiation is not affected notably. The simulated flow gradients show a wake region in the downstream direction, and the simulated acoustic field in the flow show that the region causes a wave-guide effect focusing the sound in the direction.

  4. Effectiveness of Existing International Nuclear Liability Regime

    International Nuclear Information System (INIS)

    Al-Doais, Salwa; Kessel, Daivd

    2015-01-01

    The first convention was the Paris Convention on Third Party Liability in the Field of Nuclear Energy (the Paris Convention) had been adopted on 29 July 1960 under the auspices of the OECD, and entered into force on 1 April 1968. In 1963,the Brussels Convention - supplementary to the Paris Convention- was adopted in to provide additional funds to compensate damage as a result of a nuclear incident where Paris Convention funds proved to be insufficient. The IAEA's first convention was the Vienna Convention on Civil Liability for Nuclear Damage (the Vienna Convention) which adopted on 21 May 1963,and entered into force in 1977. Both the Paris Convention and the Vienna Convention laid down very similar nuclear liability rules based on the same general principles. The broad principles in these conventions can be summarized as follows: 1- The no-fault liability principle (strict liability) 2- Liability is channeled exclusively to the operator of the nuclear installation (legal channeling) 3- Only courts of the state in which the nuclear accident occurs would have jurisdiction (exclusive jurisdiction) 4- Limitation of the amount of liability and the time frame for claiming damages (limited liability) 5- The operator is required to have adequate insurance or financial guarantees to the extent of its liability amount (liability must be financially secured). 6- Liability is limited in time. Compensation rights are extinguished after specific time. 7- Non-discrimination of victims on the grounds of nationality, domicile or residence. Nuclear liability conventions objective is to provide adequate compensation payments to victims of a nuclear accident. Procedures for receiving these compensation are controlled by some rules such as exclusive jurisdiction, that rule need a further amendment to ensure the effectiveness of the exiting nuclear liability regime . Membership of the Conventions is a critical issue, because the existence of the conventions without being party to

  5. Effectiveness of Existing International Nuclear Liability Regime

    Energy Technology Data Exchange (ETDEWEB)

    Al-Doais, Salwa; Kessel, Daivd [KEPCO International Nuclear Graduate School, Daejeon (Korea, Republic of)

    2015-10-15

    The first convention was the Paris Convention on Third Party Liability in the Field of Nuclear Energy (the Paris Convention) had been adopted on 29 July 1960 under the auspices of the OECD, and entered into force on 1 April 1968. In 1963,the Brussels Convention - supplementary to the Paris Convention- was adopted in to provide additional funds to compensate damage as a result of a nuclear incident where Paris Convention funds proved to be insufficient. The IAEA's first convention was the Vienna Convention on Civil Liability for Nuclear Damage (the Vienna Convention) which adopted on 21 May 1963,and entered into force in 1977. Both the Paris Convention and the Vienna Convention laid down very similar nuclear liability rules based on the same general principles. The broad principles in these conventions can be summarized as follows: 1- The no-fault liability principle (strict liability) 2- Liability is channeled exclusively to the operator of the nuclear installation (legal channeling) 3- Only courts of the state in which the nuclear accident occurs would have jurisdiction (exclusive jurisdiction) 4- Limitation of the amount of liability and the time frame for claiming damages (limited liability) 5- The operator is required to have adequate insurance or financial guarantees to the extent of its liability amount (liability must be financially secured). 6- Liability is limited in time. Compensation rights are extinguished after specific time. 7- Non-discrimination of victims on the grounds of nationality, domicile or residence. Nuclear liability conventions objective is to provide adequate compensation payments to victims of a nuclear accident. Procedures for receiving these compensation are controlled by some rules such as exclusive jurisdiction, that rule need a further amendment to ensure the effectiveness of the exiting nuclear liability regime . Membership of the Conventions is a critical issue, because the existence of the conventions without being party to

  6. Numerical simulation of wall roughness effects in cavitating flow

    International Nuclear Information System (INIS)

    Echouchene, F.; Belmabrouk, H.; Le Penven, L.; Buffat, M.

    2011-01-01

    Hydrodynamic cavitation has an important effect on the performance of Diesel injectors. It influences the nature of the fuel spray and the efficiency of the combustion process. In the present study, we investigate numerically the effect of wall roughness in the cavitating and turbulent flow developing inside a Diesel injector. The mixture model based on a single fluid is adopted and the commercial Fluent software is used to solve the transport equations. The discharge coefficient C d is computed for different cavitation numbers and wall roughness heights. Profiles of density mixture, vapor volume fraction, mean velocity and turbulent kinetic energy are reported. The effects of wall roughness and injection pressure are analyzed.

  7. Eye wash water flow direction study: an evaluation of the effectiveness of eye wash devices with opposite directional water flow.

    Science.gov (United States)

    Fogt, Jennifer S; Jones-Jordan, Lisa A; Barr, Joseph T

    2018-01-01

    New designs of eye wash stations have been developed in which the direction of water flow from the fountain has been reversed, with two water streams originating nasally in both eyes and flowing toward the temporal side of each eye. No study has been done to determine the ideal direction of water flow coming from the eye wash in relation to the eye. Ophthalmic eye examinations were conducted before and after the use of two eye wash stations with opposite water flow directionality. Fluorescein was instilled in both eyes before using an eye wash to measure the effectiveness of the water flow. Subjects were surveyed upon their experiences using the eye washes. Ophthalmic examination found no significant difference in the efficacy of the eye washes with nasal-to-temporal water flow when compared to temporal-to-nasal water flow direction.

  8. Optical PIV and LDV Comparisons of Internal Flow Investigations in SHF Impeller

    Directory of Open Access Journals (Sweden)

    G. Wuibaut

    2006-01-01

    Full Text Available The paper presents a comparison between two sets of experimental results in a centrifugal flow pump. The tested impeller is the so-called SHF impeller for which many experimental data have been continuously produced to built databases for CFD code validations with various levels of approximation. Measurements have been performed using optical techniques: 2D particle image velocimetry (PIV technique on an air test model and 2D laser doppler velocimetry (LDV technique on a water model, both for different flow rates. For the present study, results obtained by these optical techniques are compared together in terms of phase averaged velocity and velocity fluctuations inside the impeller flow passage for design flow rate.

  9. Status of effectiveness in internal audit in Nuclear Malaysia

    International Nuclear Information System (INIS)

    Nik Arlina Nik Ali; Noriah Mod Ali

    2010-01-01

    Full text: Internal Audit (IA) is a necessity process to obtain the certification of ISO 9001 and ISO/IEC 17025.Basically the content of this paperwork is to discuss on the effectiveness of Internal Audit conducted base on the audit report result which containing the information that have been recorded regarding the non-compliance's towards the certification standard and opportunity of improvements. (author)

  10. The 'horizontal direct effect' of EU international agreements

    DEFF Research Database (Denmark)

    Gáspár-Szilágyi, Szilárd

    2015-01-01

    This article looks at a less discussed topic in European legal scholarship: the horizontal direct effect of EU international agreements and the Court of Justice’s apparent reluctance to expressly confirm it. It is argued that the direct effect of EU international agreements has been confirmed...... in proceedings involving private individuals/professionals against the private regulatory bodies of a profession or a State owned and controlled entity. However, direct effect has not yet been expressly confirmed in cases involving veritable horizontal relationships, between private parties of equal positions...

  11. Effect of wettability on scale-up of multiphase flow from core-scale to reservoir fine-grid-scale

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Y.C.; Mani, V.; Mohanty, K.K. [Univ. of Houston, TX (United States)

    1997-08-01

    Typical field simulation grid-blocks are internally heterogeneous. The objective of this work is to study how the wettability of the rock affects its scale-up of multiphase flow properties from core-scale to fine-grid reservoir simulation scale ({approximately} 10{prime} x 10{prime} x 5{prime}). Reservoir models need another level of upscaling to coarse-grid simulation scale, which is not addressed here. Heterogeneity is modeled here as a correlated random field parameterized in terms of its variance and two-point variogram. Variogram models of both finite (spherical) and infinite (fractal) correlation length are included as special cases. Local core-scale porosity, permeability, capillary pressure function, relative permeability functions, and initial water saturation are assumed to be correlated. Water injection is simulated and effective flow properties and flow equations are calculated. For strongly water-wet media, capillarity has a stabilizing/homogenizing effect on multiphase flow. For small variance in permeability, and for small correlation length, effective relative permeability can be described by capillary equilibrium models. At higher variance and moderate correlation length, the average flow can be described by a dynamic relative permeability. As the oil wettability increases, the capillary stabilizing effect decreases and the deviation from this average flow increases. For fractal fields with large variance in permeability, effective relative permeability is not adequate in describing the flow.

  12. Reflux venous flow in dural sinus and internal jugular vein on 3D time-of-flight MR angiography

    International Nuclear Information System (INIS)

    Jang, Jinhee; Kim, Bum-soo; Kim, Bom-yi; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Byun, Jae Young

    2013-01-01

    Reflux venous signal on the brain and neck time-of-flight magnetic resonance angiography (TOF MRA) is thought to be related to a compressed left brachiocephalic vein. This study is aimed to assess the prevalence of venous reflux flow in internal jugular vein (IJV), sigmoid sinus/transverse sinus (SS/TS), and inferior petrosal sinus (IPS) on the brain and neck TOF MRA and its pattern. From the radiology database, 3,475 patients (1,526 men, 1,949 women, age range 19-94, median age 62 years) with brain and neck standard 3D TOF MRA at 3 T and 1.5 T were identified. Rotational maximal intensity projection images of 3D TOF MRA were assessed for the presence of reflux flow in IJV, IPS, and SS/TS. Fifty-five patients (1.6 %) had reflux flow, all in the left side. It was more prevalent in females (n = 43/1,949, 2.2 %) than in males (n = 12/1,526, 0.8 %) (p = 0.001). The mean age of patients with reflux flow (66 years old) was older than those (60 years old) without reflux flow (p = 0.001). Three patients had arteriovenous shunt in the left arm for hemodialysis. Of the remaining 52 patients, reflux was seen on IJV in 35 patients (67.3 %). There were more patients with reflux flow seen on SS/TS (n = 34) than on IPS (n = 25). Venous reflux flow on TOF MRA is infrequently observed, and reflux pattern is variable. Because it is exclusively located in the left side, the reflux signal on TOF MRA could be an alarm for an undesirable candidate for a contrast injection on the left side for contrast-enhanced imaging study. (orig.)

  13. Investigation of the Shear Flow Effect and Tip Clearance on a Low Speed Axial Flow Compressor Cascade

    Directory of Open Access Journals (Sweden)

    Mahesh Varpe

    2013-01-01

    Full Text Available This paper explores the effect of inlet shear flow on the tip leakage flow in an axial flow compressor cascade. A flow with a high shear rate is generated in the test section of an open circuit cascade wind tunnel by using a combination of screens with a prescribed solidity. It is observed that a stable shear flow of shear rate 1.33 is possible and has a gradual decay rate until 15 times the height of the shear flow generator downstream. The computational results obtained agree well with the available experimental data on the baseline configuration. The detailed numerical analysis shows that the tip clearance improves the blade loading near the tip through the promotion of favorable incidence by the tip leakage flow. The tip clearance shifts the centre of pressure on the blade surface towards the tip. It, however, has no effect on the distribution of end wall loss and deviation angle along the span up to 60% from the hub. In the presence of a shear inflow, the end wall effects are considerable. On the other hand, with a shear inflow, the effects of tip leakage flow are observed to be partly suppressed. The shear flow reduces the tip leakage losses substantially in terms of kinetic energy associated with it.

  14. Shifting Patterns of International Higher Education: Ebb and Flow or Sea Change?

    Science.gov (United States)

    Middlehurst, Robin

    2013-01-01

    In November 2012, the US Department of Education published its first-ever "fully articulated international strategy." Its two strategic goals are to strengthen US education and advance the international priorities of the US through increasing the global competencies of students, learning from other countries, and engaging in education…

  15. A Lesson about the Circular Flow. Active Learning Lessons. Economics International.

    Science.gov (United States)

    Landfried, Janet

    This lesson plan was developed through "Economics International," an international program to help build economic education infrastructures in the emerging market economies. It provides a lesson description; appropriate grade level; economic concepts; content standards and benchmarks; related subjects; instructional objectives; time…

  16. "Families" in International Context: Comparing Institutional Effects across Western Societies

    Science.gov (United States)

    Cooke, Lynn Prince; Baxter, Janeen

    2010-01-01

    We review comparative evidence of institutional effects on families in Western societies. We focus on 2 key aspects of family life: gendered divisions of labor and people's transitions into, within, and out of relationships. Many individual-level models assume the effects are robust across countries. The international evidence over the past decade…

  17. Effect of Energetic Plasma Flux on Flowing Liquid Lithium Surfaces

    Science.gov (United States)

    Kalathiparambil, Kishor; Jung, Soonwook; Christenson, Michael; Fiflis, Peter; Xu, Wenyu; Szott, Mathew; Ruzic, David

    2014-10-01

    An operational liquid lithium system with steady state flow driven by thermo-electric magneto-hydrodynamic force and capable of constantly refreshing the plasma exposed surface have been demonstrated at U of I. To evaluate the system performance in reactor relevant conditions, specifically to understand the effect of disruptive plasma events on the performance of the liquid metal PFCs, the setup was integrated to a pulsed plasma generator. A coaxial plasma generator drives the plasma towards a theta pinch which preferentially heats the ions, simulating ELM like flux, and the plasma is further guided towards the target chamber which houses the flowing lithium system. The effect of the incident flux is examined using diagnostic tools including triple Langmuir probe, calorimeter, rogowski coils, Ion energy analyzers, and fast frame spectral image acquisition with specific optical filters. The plasma have been well characterized and a density of ~1021 m-3, with electron temperature ~10 - 20 eV is measured, and final plasma velocities of 34 - 74 kms-1 have been observed. Calorimetric measurements using planar molybdenum targets indicate a maximum plasma energy (with 6 kV plasma gun and 20 kV theta pinch) of 0.08 MJm-2 with plasma divergence effects resulting in marginal reduction of 40 +/- 23 J in plasma energy. Further results from the other diagnostic tools, using the flowing lithium targets and the planar targets coated with lithium will be presented. DOE DE-SC0008587.

  18. On the effect of pulsating flow on surge margin of small centrifugal compressors for automotive engines

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, J.; Climent, H.; Guardiola, C.; Tiseira, A. [CMT-Motores Termicos, Universidad Politecnica de Valencia (Spain); Camino de Vera s/n, E 46022, Valencia (Spain)

    2009-11-15

    Surge is becoming a limiting factor in the design of boosting systems of downsized diesel engines. Although standard compressor flowcharts are used for the selection of those machines for a given application, on-engine conditions widely differ from steady flow conditions, thus affecting compressor behaviour and consequently surge phenomenon. In this paper the effect of pulsating flow is investigated by means of a steady gas-stand that has been modified to produce engine-like pulsating flow. The effect of pressure pulses' amplitude and frequency on the compressor surge line location has been checked. Results show that pulsating flow in the 40-67 Hz range (corresponding to characteristic pulsation when boosting an internal combustion engine) increases surge margin. This increased margin is similar for all the tested frequencies but depends on pulsation amplitude. In a further step, a non-steady compressor model is used for modelling the tests, thus allowing a deeper analysis of the involved phenomena. Model results widely agree with experimental results. (author)

  19. Internal flow inside droplets within a concentrated emulsion during droplet rearrangement

    Science.gov (United States)

    Leong, Chia Min; Gai, Ya; Tang, Sindy K. Y.

    2018-03-01

    Droplet microfluidics, in which each droplet serves as a micro-reactor, has found widespread use in high-throughput biochemical screening applications. These droplets are often concentrated at various steps to form a concentrated emulsion. As part of a serial interrogation and sorting process, such concentrated emulsions are typically injected into a tapered channel leading to a constriction that fits one drop at a time for the probing of droplet content in a serial manner. The flow physics inside the droplets under these flow conditions are not well understood but are critical for predicting and controlling the mixing of reagents inside the droplets as reactors. Here we investigate the flow field inside droplets of a concentrated emulsion flowing through a tapered microchannel using micro-particle image velocimetry. The confining geometry of the channel forces the number of rows of drops to reduce by one at specific and uniformly spaced streamwise locations, which are referred to as droplet rearrangement zones. Within each rearrangement zone, the phase-averaged velocity results show that the motion of the droplets involved in the rearrangement process, also known as a T1 event, creates vortical structures inside themselves and their adjacent droplets. These flow structures increase the circulation inside droplets up to 2.5 times the circulation in droplets at the constriction. The structures weaken outside of the rearrangement zones suggesting that the flow patterns created by the T1 process are transient. The time scale of circulation is approximately the same as the time scale of a T1 event. Outside of the rearrangement zones, flow patterns in the droplets are determined by the relative velocity between the continuous and disperse phases.

  20. Effect of attack angle on flow characteristic of centrifugal fan

    Science.gov (United States)

    Wu, Y.; Dou, H. S.; Wei, Y. K.; Chen, X. P.; Chen, Y. N.; Cao, W. B.

    2016-05-01

    In this paper, numerical simulation is performed for the performance and internal flow of a centrifugal fan with different operating conditions using steady three-dimensional incompressible Navier-Stokes equations coupled with the RNG k-e turbulent model. The performance curves, the contours of static pressure, total pressure, radial velocity, relative streamlines and turbulence intensity at different attack angles are obtained. The distributions of static pressure and velocity on suction surface and pressure surface in the same impeller channel are compared for various attack angles. The research shows that the efficiency of the centrifugal fan is the highest when the attack angle is 8 degree. The main reason is that the vortex flow in the impeller is reduced, and the jet-wake pattern is weakened at the impeller outlet. The pressure difference between pressure side and suction side is smooth and the amplitude of the total pressure fluctuation is low along the circumferential direction. These phenomena may cause the loss reduced for the attack angle of about 8 degree.

  1. The Effects of the International Contract for Sale of Goods

    Directory of Open Access Journals (Sweden)

    Berlingher Daniel

    2017-06-01

    Full Text Available The contracts are the indispensable legal instruments for any economic transaction. The international sale contract is the main legal instrument by which international commerce is carried out and through which the movement of goods from producer to consumer is ensured within cross-border relations. The sale contract in international commerce is the legal act by which the parties, the seller and the buyer, belonging to different states, commit each other to transfer the property of a good in return for payment of a price. Regarding the general rules applicable to the contract of international sale of goods, they are regulated by the “United Nations Convention on Contracts for the International Sale of Goods from Vienna”. The Convention has adopted uniform rules to govern the international sale of goods contract, if the parties have not chosen expressly for the application of other rules. In this study I present the effects of international sale of goods in the light of the rules of the Vienna Convention of 1980.

  2. The Impact of Technical–Nontechnical Factors Synergy on Innovation Performance: The Moderating Effect of Talent Flow

    Directory of Open Access Journals (Sweden)

    Hong-Bo Shi

    2018-03-01

    Full Text Available Innovation and talent are the guarantee of the sustainable development of an enterprise. However, internet companies are facing two major problems: innovation scarcity and frequent talent flow. The gradual intensification of competition is leading internet companies to realize the importance of collaborative innovation of an enterprise’s internal elements. Previous studies have pointed out that appropriate talent flow is conducive to improve the corporation’s innovation performance, too low or too high talent flow has a negative impact on the enterprise’s innovation ability. This study explores the relationship between talent flow, technical–nontechnical element synergy and collaborative innovation performance in the internet industry. The results show that the technical–nontechnical element synergy is beneficial to improve the collaborative innovation performance, and the comprehensive coordination of the elements can generate integration advantages that single element synergy cannot produce. As a moderator variable, talent flow can positively moderate the relationship between technical–market synergy, technical–strategy synergy, technical–institution synergy and collaborative innovation performance. However, because of the particularity of organization and culture, talent flow has no moderating effect on the relationship between technical–culture synergy, technical–organization synergy and innovation performance. Finally, this paper puts forward some suggestions on how to promote internet enterprise internal element synergy and use the talent flow frequency to improve collaborative innovation performance.

  3. Experimental investigation of certain internal condensing and boiling flows: Their sensitivity to pressure fluctuations and heat transfer enhancements

    Science.gov (United States)

    Kivisalu, Michael Toomas

    Space-based (satellite, scientific probe, space station, etc.) and millimeter -- to -- micro-scale (such as are used in high power electronics cooling, weapons cooling in aircraft, etc.) condensers and boilers are shear/pressure driven. They are of increasing interest to system engineers for thermal management because flow boilers and flow condensers offer both high fluid flow-rate-specific heat transfer capacity and very low thermal resistance between the fluid and the heat exchange surface, so large amounts of heat may be removed using reasonably-sized devices without the need for excessive temperature differences. However, flow stability issues and degredation of performance of shear/pressure driven condensers and boilers due to non-desireable flow morphology over large portions of their lengths have mostly prevented their use in these applications. This research is part of an ongoing investigation seeking to close the gap between science and engineering by analyzing two key innovations which could help address these problems. First, it is recommended that the condenser and boiler be operated in an innovative flow configuration which provides a non-participating core vapor stream to stabilize the annular flow regime throughout the device length, accomplished in an energy-efficient manner by means of ducted vapor re-circulation. This is demonstrated experimentally.. Second, suitable pulsations applied to the vapor entering the condenser or boiler (from the re-circulating vapor stream) greatly reduce the thermal resistance of the already effective annular flow regime. For experiments reported here, application of pulsations increased time-averaged heat-flux up to 900 % at a location within the flow condenser and up to 200 % at a location within the flow boiler, measured at the heat-exchange surface. Traditional fully condensing flows, reported here for comparison purposes, show similar heat-flux enhancements due to imposed pulsations over a range of frequencies

  4. Research for rolling effects on flow pattern of gas-water flow in horizontal tubes

    International Nuclear Information System (INIS)

    Luan Feng; Yan Changqi

    2007-01-01

    The flow pattern transition of two-phase flow is caused by the inertial force resulted from rolling and incline of horizontal tubes under rolling state. an experimental study on the flow patterns of gas-water flow was carried out in horizontal tubes under rolling state, which rolling period is 15 second and rolling angle is 10 degrees, and a pattern flow picture is shown. It was found that there are two flow patterns in one rolling period under some gas flux and water flux. (authors)

  5. Graphene field-effect transistor application for flow sensing

    Directory of Open Access Journals (Sweden)

    Łuszczek Maciej

    2017-01-01

    Full Text Available Microflow sensors offer great potential for applications in microfluidics and lab-on-a-chip systems. However, thermal-based sensors, which are commonly used in modern flow sensing technology, are mainly made of materials with positive temperature coefficients (PTC and suffer from a self-heating effect and slow response time. Therefore, the design of novel devices and careful selection of materials are required to improve the overall flow sensor performance. In this work we propose graphene field-effect transistor (GFET to be used as microflow sensor. Temperature distribution in graphene channel was simulated and the analysis of heat convection was performed to establish the relation between the fluidic flow velocity and the temperature gradient. It was shown that the negative temperature coefficient (NTC of graphene could enable the self-protection of the device and should minimize sensing error from currentinduced heating. It was also argued that the planar design of the GFET sensor makes it suitable for the real application due to supposed mechanical stability of such a construction.

  6. Effects of continuum breakdown on hypersonic aerothermodynamics for reacting flow

    Science.gov (United States)

    Holman, Timothy D.; Boyd, Iain D.

    2011-02-01

    This study investigates the effects of continuum breakdown on the surface aerothermodynamic properties (pressure, stress, and heat transfer rate) of a sphere in a Mach 25 flow of reacting air in regimes varying from continuum to a rarefied gas. Results are generated using both continuum [computational fluid dynamics (CFD)] and particle [direct simulation Monte Carlo (DSMC)] approaches. The DSMC method utilizes a chemistry model that calculates the backward rates from an equilibrium constant. A preferential dissociation model is modified in the CFD method to better compare with the vibrationally favored dissociation model that is utilized in the DSMC method. Tests of these models are performed to confirm their validity and to compare the chemistry models in both numerical methods. This study examines the effect of reacting air flow on continuum breakdown and the surface properties of the sphere. As the global Knudsen number increases, the amount of continuum breakdown in the flow and on the surface increases. This increase in continuum breakdown significantly affects the surface properties, causing an increase in the differences between CFD and DSMC. Explanations are provided for the trends observed.

  7. Numerical optimization of conical flow waveriders including detailed viscous effects

    Science.gov (United States)

    Bowcutt, Kevin G.; Anderson, John D., Jr.; Capriotti, Diego

    1987-01-01

    A family of optimized hypersonic waveriders is generated and studied wherein detailed viscous effects are included within the optimization process itself. This is in contrast to previous optimized waverider work, wherein purely inviscid flow is used to obtain the waverider shapes. For the present waveriders, the undersurface is a streamsurface of an inviscid conical flowfield, the upper surface is a streamsurface of the inviscid flow over a tapered cylinder (calculated by the axisymmetric method of characteristics), and the viscous effects are treated by integral solutions of the boundary layer equations. Transition from laminar to turbulent flow is included within the viscous calculations. The optimization is carried out using a nonlinear simplex method. The resulting family of viscous hypersonic waveriders yields predicted high values of lift/drag, high enough to break the L/D barrier based on experience with other hypersonic configurations. Moreover, the numerical optimization process for the viscous waveriders results in distinctly different shapes compared to previous work with inviscid-designed waveriders. Also, the fine details of the viscous solution, such as how the shear stress is distributed over the surface, and the location of transition, are crucial to the details of the resulting waverider geometry. Finally, the moment coefficient variations and heat transfer distributions associated with the viscous optimized waveriders are studied.

  8. Potential Effects of Disruptive Political Trends in International Tourism Market

    Directory of Open Access Journals (Sweden)

    Ali Öztüren

    2017-05-01

    Full Text Available The purpose of this paper is to discuss the prospective effects of the latest political incidences on the international tourism market. In this context, the arguments are based on the implications of the USA elections and the Brexit. The methodology of this paper comprises the discussion of the debates related to the recent political experiences. International tourism activities cannot be isolated from the political environment. It is clear that the new political incidences will require novel insights and strategies in conducting international tourism business globally. This paper provides a viewpoint of the today’s political scenarios that will certainly affect the international tourism market. It can be used to comprehend insights that can be used to plan the tourism futures.

  9. Effect of Surface Modification and Macrophage Phenotype on Particle Internalization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Daniel [Iowa State University; Phan, Ngoc [Iowa State University; Isely, Christopher [Iowa State University; Bruene, Lucas [Iowa State University; Bratlie, Kaitlin M [Ames Laboratory

    2014-11-10

    Material properties play a key role in the cellular internalization of polymeric particles. In the present study, we have investigated the effects of material characteristics such as water contact angle, zeta potential, melting temperature, and alternative activation of complement on particle internalization for pro-inflammatory, pro-angiogenic, and naïve macrophages by using biopolymers (~600 nm), functionalized with 13 different molecules. Understanding how material parameters influence particle internalization for different macrophage phenotypes is important for targeted delivery to specific cell populations. Here, we demonstrate that material parameters affect the alternative pathway of complement activation as well as particle internalization for different macrophage phenotypes. Here, we show that the quantitative structure–activity relationship method (QSAR) previously used to predict physiochemical properties of materials can be applied to targeting different macrophage phenotypes. These findings demonstrated that targeted drug delivery to macrophages could be achieved by exploiting material parameters.

  10. Numerical and experimental investigation of the bell-mouth inlet design of a centrifugal fan for higher internal flow rate

    International Nuclear Information System (INIS)

    Kim, Sang Hyeon; Heo, Seung; Cheong, Cheolung; Kim, Tae Hoon

    2013-01-01

    The energy efficiency of a household refrigerator is one of the most critical characteristics considered by manufacturers and consumers. Numerous studies in various fields have been conducted to increase energy efficiency. One of the most efficient methods to reduce the energy consumption of a refrigerator is by improving the performance of fans inside the refrigerator. A number of studies reported various ways to enhance fan performance. However, the majority of these studies focused solely on the fan and did not consider the working environment of the fan, such as the inlet and outlet flow characteristics. The expected performance of fans developed without consideration of these characteristics cannot be determined because complex inlet and outlet flow passage could adversely affect performance. This study investigates the effects of the design of the bell-mouth inlet on the performance of a centrifugal fan in a household refrigerator. In preliminary numerical studies, significant flow loss is identified through the bell-mouth inlet in the target fan system. Several design factors such as tip clearance, inner fence, motor-box struts, and guide vane are proposed to resolve these flow losses. The effects of these factors on fan performance are investigated using computational fluid dynamics techniques to solve incompressible Reynolds-averaged Navier-Stokes equations for predicting the circulating flow of the fan. Experiments are then performed to validate the numerical predictions. Results indicate that four design factors positively affect fan performance in terms of flow rate. The guide vane is the most effective design factor to consider for improving fan performance. Further studies are conducted to investigate the detailed effects of the guide vane by varying its install angle, install location, height, and length. These studies determine the optimum design of the guide vane to achieve the highest performance of the fan and the related flow characteristics

  11. Numerical and experimental investigation of the bell-mouth inlet design of a centrifugal fan for higher internal flow rate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Hyeon; Heo, Seung; Cheong, Cheolung [Pusan National University, Busan (Korea, Republic of); Kim, Tae Hoon [Refrigeration Division, Changwon (Korea, Republic of)

    2013-08-15

    The energy efficiency of a household refrigerator is one of the most critical characteristics considered by manufacturers and consumers. Numerous studies in various fields have been conducted to increase energy efficiency. One of the most efficient methods to reduce the energy consumption of a refrigerator is by improving the performance of fans inside the refrigerator. A number of studies reported various ways to enhance fan performance. However, the majority of these studies focused solely on the fan and did not consider the working environment of the fan, such as the inlet and outlet flow characteristics. The expected performance of fans developed without consideration of these characteristics cannot be determined because complex inlet and outlet flow passage could adversely affect performance. This study investigates the effects of the design of the bell-mouth inlet on the performance of a centrifugal fan in a household refrigerator. In preliminary numerical studies, significant flow loss is identified through the bell-mouth inlet in the target fan system. Several design factors such as tip clearance, inner fence, motor-box struts, and guide vane are proposed to resolve these flow losses. The effects of these factors on fan performance are investigated using computational fluid dynamics techniques to solve incompressible Reynolds-averaged Navier-Stokes equations for predicting the circulating flow of the fan. Experiments are then performed to validate the numerical predictions. Results indicate that four design factors positively affect fan performance in terms of flow rate. The guide vane is the most effective design factor to consider for improving fan performance. Further studies are conducted to investigate the detailed effects of the guide vane by varying its install angle, install location, height, and length. These studies determine the optimum design of the guide vane to achieve the highest performance of the fan and the related flow characteristics

  12. Effect of cross-flow direction of coolant on film cooling effectiveness with one inlet and double outlet hole injection

    Directory of Open Access Journals (Sweden)

    Guangchao Li

    2012-12-01

    Full Text Available In order to study the effect of cross-flow directions of an internal coolant on film cooling performance, the discharge coefficients and film cooling effectiveness with one inlet and double outlet hole injections were simulated. The numerical results show that two different cross-flow directions of the coolant cause the same decrease in the discharge coefficients as that in the case of supplying coolant by a plenum. The different proportion of the mass flow out of the two outlets of the film hole results in different values of the film cooling effectiveness for three different cases of coolant supplies. The film cooling effectiveness is the highest for the case of supplying coolant by the plenum. At a lower blowing ratio of 1.0, the film cooling effectiveness with coolant injection from the right entrance of the passage is higher than that from the left entrance of the passage. At a higher blowing ratio of 2.0, the opposite result is found.

  13. Opposing flow in square porous annulus: Influence of Dufour effect

    International Nuclear Information System (INIS)

    Athani, Abdulgaphur; Al-Rashed, Abdullah A. A. A.; Khaleed, H. M. T.

    2016-01-01

    Heat and mass transfer in porous medium is very important area of research which is also termed as double diffusive convection or thermo-solutal convection. The buoyancy ratio which is the ratio of thermal to concentration buoyancy can have negative values thus leading to opposing flow. This article is aimed to study the influence of Dufour effect on the opposing flow in a square porous annulus. The partial differential equations that govern the heat and mass transfer behavior inside porous medium are solved using finite element method. A three node triangular element is used to divide the porous domain into smaller elements. Results are presented with respect to geometric and physical parameters such as duct diameter ratio, Rayleigh number, radiation parameter etc. It is found that the heat transfer increase with increase in Rayleigh number and radiation parameter. It is observed that Dufour coefficient has more influence on velocity profile.

  14. Opposing flow in square porous annulus: Influence of Dufour effect

    Energy Technology Data Exchange (ETDEWEB)

    Athani, Abdulgaphur, E-mail: abbu.bec@gmail.com [Dept. of Mechanical Engineering, Anjuman Institute of Technology & Management, Bhatkal (India); Al-Rashed, Abdullah A. A. A., E-mail: aa.alrashed@paaet.edu.kw [Dept. of Automotive and Marine Engineering Technology, College of Technological Studies, The Public Authority for Applied Education and Training (Kuwait); Khaleed, H. M. T., E-mail: khalid-tan@yahoo.com [Dept of Mechanical Engineering, Faculty of Engineering, Islamic University, Madinah Munawwarra (Saudi Arabia)

    2016-06-21

    Heat and mass transfer in porous medium is very important area of research which is also termed as double diffusive convection or thermo-solutal convection. The buoyancy ratio which is the ratio of thermal to concentration buoyancy can have negative values thus leading to opposing flow. This article is aimed to study the influence of Dufour effect on the opposing flow in a square porous annulus. The partial differential equations that govern the heat and mass transfer behavior inside porous medium are solved using finite element method. A three node triangular element is used to divide the porous domain into smaller elements. Results are presented with respect to geometric and physical parameters such as duct diameter ratio, Rayleigh number, radiation parameter etc. It is found that the heat transfer increase with increase in Rayleigh number and radiation parameter. It is observed that Dufour coefficient has more influence on velocity profile.

  15. SOLAR ROTATION EFFECTS ON THE HELIOSHEATH FLOW NEAR SOLAR MINIMA

    International Nuclear Information System (INIS)

    Borovikov, Sergey N.; Pogorelov, Nikolai V.; Ebert, Robert W.

    2012-01-01

    The interaction between fast and slow solar wind (SW) due to the Sun's rotation creates corotating interaction regions (CIRs), which further interact with each other creating complex plasma structures at large heliospheric distances. We investigate the global influence of CIRs on the SW flow in the inner heliosheath between the heliospheric termination shock (TS) and the heliopause. The stream interaction model takes into account the major global effects due to slow-fast stream interaction near solar minima. The fast and slow wind parameters are derived from the Ulysses observations. We investigate the penetration of corotating structures through the TS and their further propagation through the heliosheath. It is shown that the heliosheath flow structure may experience substantial modifications, including local decreases in the radial velocity component observed by Voyager 1.

  16. International flow of media and the evolution of his speech | Moussa ...

    African Journals Online (AJOL)

    Journal Home > Vol 19, No 2 (2011) > ... Due to the development of communication technologies and international media, this country has ... of media, Information and Communication Technologies, Speech, Ideological domination, Strategic ...

  17. Effect of Unsaturated Flow on Delayed Response of Unconfined Aquifiers to Pumping

    Science.gov (United States)

    Tartakovsky, G.; Neuman, S. P.

    2005-12-01

    A new analytical solution is presented for the delayed response process characterizing flow to a partially penetrating well in an unconfined aquifer. The new solution generalizes that of Neuman [1972, 1974] by accounting for unsaturated flow above the water table. Axially symmetric three-dimensional flow in the unsaturated zone is described by a linearized version of Richards' equation in which hydraulic conductivity and water content vary exponentially with incremental capillary pressure head relative to its air entry value (defining the interface between the saturated and unsaturated zones). Unsaturated soil properties are characterized by an exponent κ having the dimension of inverse length and a dimensionless exponent κD = κb where b is initial saturated thickness. Our treatment of the unsaturated zone is similar to that of Kroszynski and Dagan [1975] who however have ignored internal (artesian) aquifer storage. It has been suggested by Boulton [1954, 1963, 1970] and Neuman [1972, 1974], and is confirmed by our solution, that internal storage is required to reproduce the early increase in drawdown characterizing delayed response to pumping in typical aquifers. According to our new solution such aquifers are characterized by relatively large κ_ D values, typically 10 or larger; in the limit as κD tends to infinity (the soil unsaturated water retention capacity becomes insignificant and/or aquifer thickness become large), unsaturated flow becomes unimportant and our solution reduces to that of Neuman. In typical cases corresponding to κD larger than or equal to 10, unsaturated flow is found to have little impact on early and late dimensionless time behaviors of drawdown measured wholly or in part at some distance below the water table; unsaturated flow causes drawdown to increase slightly at intermediate dimensionless time values that represent transition from an early artesian dominated to a late water-table dominated flow regime. The increase in drawdown

  18. High Enthalpy Effects on Two Boundary Layer Disturbances in Supersonic and Hypersonic Flow

    Science.gov (United States)

    Wagnild, Ross Martin

    The fluid flow phenomenon of boundary layer transition is a complicated and difficult process to model and predict. The importance of the state of the boundary layer with regard to vehicle design cannot be understated. The high enthalpy environment in which high speed vehicles operate in further complicates the transition process by adding several more degrees of freedom. In this environment, the internal properties of the gas can stabilize or destabilize the boundary layer as well as modify the disturbances that cause transition. In the current work, the interaction of two types of disturbances with the high enthalpy flow environment are analyzed. The first is known as a second mode disturbance, which is acoustic in nature. The second type is known as a transient growth disturbance and is associated with flows behind roughness elements. Theoretical analyses, linear stability analyses, and computation fluid dynamics (CFD) are used to determine the ways in which these disturbances interact with the high enthalpy environment as well as the consequences of these interactions. First, acoustic wave are directly studied in order to gain a basic understanding of the response of second mode disturbances in the high enthalpy boundary layer. Next, this understanding is used in interpreting the results of several computations attempting to simulate the flow through a high enthalpy flow facility as well as experiments attempting to take advantage of the acoustic interaction with the high enthalpy environment. Because of the difficulty in modeling these experiments, direct simulations of acoustic waves in a hypersonic flow of a gas with molecular vibration are performed. Lastly, compressible transient growth disturbances are simulated using a linear optimal disturbance solver as well as a CFD solver. The effect of an internal molecular process on this type of disturbance is tested through the use of a vibrational mode. It is the goal of the current work to reinforce the

  19. Spatial stochasticity and non-continuum effects in gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Dadzie, S. Kokou, E-mail: k.dadzie@glyndwr.ac.uk [Mechanical and Aeronautical Engineering, Glyndwr University, Mold Road, Wrexham LL11 2AW (United Kingdom); Reese, Jason M., E-mail: jason.reese@strath.ac.uk [Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ (United Kingdom)

    2012-02-06

    We investigate the relationship between spatial stochasticity and non-continuum effects in gas flows. A kinetic model for a dilute gas is developed using strictly a stochastic molecular model reasoning, without primarily referring to either the Liouville or the Boltzmann equations for dilute gases. The kinetic equation, a stochastic version of the well-known deterministic Boltzmann equation for dilute gas, is then associated with a set of macroscopic equations for the case of a monatomic gas. Tests based on a heat conduction configuration and sound wave dispersion show that spatial stochasticity can explain some non-continuum effects seen in gases. -- Highlights: ► We investigate effects of molecular spatial stochasticity in non-continuum regime. ► Present a simplify spatial stochastic kinetic equation. ► Present a spatial stochastic macroscopic flow equations. ► Show effects of the new model on sound wave dispersion prediction. ► Show effects of the new approach in density profiles in a heat conduction.

  20. Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects

    Energy Technology Data Exchange (ETDEWEB)

    Vigeesh, G.; Steiner, O. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg (Germany); Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de [New Mexico State University, Department of Astronomy, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003 (United States)

    2017-02-01

    Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in the Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.

  1. Ion transport membrane module and vessel system with directed internal gas flow

    Science.gov (United States)

    Holmes, Michael Jerome; Ohrn, Theodore R.; Chen, Christopher Ming-Poh

    2010-02-09

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an inlet adapted to introduce gas into the interior of the vessel, an outlet adapted to withdraw gas from the interior of the vessel, and an axis; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region; and (c) one or more gas flow control partitions disposed in the interior of the pressure vessel and adapted to change a direction of gas flow within the vessel.

  2. Effects of midazolam on cerebral blood flow in human volunteers

    International Nuclear Information System (INIS)

    Forster, A.; Juge, O.; Morel, D.

    1982-01-01

    The effects of intravenously administered midazolam on cerebral blood flow were evaluated in eight healthy volunteers using the 133 Xe inhalation technique. Six minutes after an intravenous dose of 0.15 mg/kg midazolam, the cerebral blood flow decreased significantly (P less than 0.001) from a value of 40.6 +/- 3.3 to a value of 27.0 +/- 5.0 ml . 100 g-1 . min-1. Cerebrovascular resistance (CVR) increased from 2.8 +/- 0.2 to 3.9 to 0.6 mmHg/(ml . 100 g-1 . min-1)(P less than 0.001). Mean arterial blood pressure decreased significantly (P less than 0.05) from 117 +/- 8 to 109 +/- 9 mmHg and arterial carbon dioxide tension increased from 33.9 +/- 2.3 to 38.6 +/- 3.2 mmHg (P less than 0.05). Arterial oxygen tension remained stable throughout the study, 484 +/- 95 mmHg before the administration of midazolam and 453 +/- 76 mmHg after. All the subjects slept after the injection of the drug and had anterograde amnesia of 24.5 +/- 5 min. The decrease in mean arterial blood pressure was probably not important since it remained in the physiologic range for cerebral blood flow autoregulation. The increase in arterial carbon dioxide tension observed after the midazolam injection may have partially counteracted the effect of this new benzodiazepine on cerebral blood flow. Our data suggest that midazolam might be a safe agent to use for the induction of anethesia in neurosurgical patients with intracranial hypertension

  3. Gas flow rate and powder flow rate effect on properties of laser metal deposited Ti6Al4V

    CSIR Research Space (South Africa)

    Pityana, S

    2013-03-01

    Full Text Available . The powder flow rate and the gas flow rate were varied to study their effect on the physical, metallurgical and mechanical properties of the deposits. The physical properties studied are: the track width, the track height and the deposit weight...

  4. Modeling Flow in Naturally Fractured Reservoirs : Effect of Fracture Aperture Distribution on Critical Sub-Network for Flow

    NARCIS (Netherlands)

    Gong, J.; Rossen, W.R.

    2014-01-01

    Fracture network connectivity and aperture (or conductivity) distribution are two crucial features controlling the flow behavior of fractured formations. The effect of connectivity on flow properties is well documented. We focus here on the influence of fracture aperture distribution. We model a

  5. Modeling flow in naturally fractured reservoirs : effect of fracture aperture distribution on dominant sub-network for flow

    NARCIS (Netherlands)

    Gong, J.; Rossen, W.R.

    2017-01-01

    Fracture network connectivity and aperture (or conductivity) distribution are two crucial features controlling flow behavior of naturally fractured reservoirs. The effect of connectivity on flow properties is well documented. In this paper, however, we focus here on the influence of fracture

  6. Combined effects of radiation and chemical reaction on MHD flow ...

    African Journals Online (AJOL)

    (2016) have studied unsteady MHD flow in porous media over exponentially accelerated plate ... boundary layer flow of heat and mass transfer over a moving vertical plate with suction. ... flow considering free convection over a porous plate.

  7. Studying flow close to an interface by total internal reflection fluorescence cross-correlation spectroscopy: Quantitative data analysis

    Science.gov (United States)

    Schmitz, R.; Yordanov, S.; Butt, H. J.; Koynov, K.; Dünweg, B.

    2011-12-01

    Total internal reflection fluorescence cross-correlation spectroscopy (TIR-FCCS) has recently [S. Yordanov , Optics ExpressOPEXFF1094-408710.1364/OE.17.021149 17, 21149 (2009)] been established as an experimental method to probe hydrodynamic flows near surfaces, on length scales of tens of nanometers. Its main advantage is that fluorescence occurs only for tracer particles close to the surface, thus resulting in high sensitivity. However, the measured correlation functions provide only rather indirect information about the flow parameters of interest, such as the shear rate and the slip length. In the present paper, we show how to combine detailed and fairly realistic theoretical modeling of the phenomena by Brownian dynamics simulations with accurate measurements of the correlation functions, in order to establish a quantitative method to retrieve the flow properties from the experiments. First, Brownian dynamics is used to sample highly accurate correlation functions for a fixed set of model parameters. Second, these parameters are varied systematically by means of an importance-sampling Monte Carlo procedure in order to fit the experiments. This provides the optimum parameter values together with their statistical error bars. The approach is well suited for massively parallel computers, which allows us to do the data analysis within moderate computing times. The method is applied to flow near a hydrophilic surface, where the slip length is observed to be smaller than 10nm, and, within the limitations of the experiments and the model, indistinguishable from zero.

  8. Mean flow generated by an internal wave packet impinging on the interface between two layers of fluid with continuous density

    Energy Technology Data Exchange (ETDEWEB)

    McHugh, John P. [The University of New Hampshire, Department of Mechanical Engineering, Kingsbury Hall, Durham, NH (United States)

    2008-04-15

    Internal waves propagating in an idealized two-layer atmosphere are studied numerically. The governing equations are the inviscid anelastic equations for a perfect gas atmosphere. The numerical formulation eliminates all variables in the linear terms except vertical velocity, which are then treated implicitly. Nonlinear terms are treated explicitly. The basic state is a two-layer flow with continuous density at the interface. Each layer has a unique constant for the Brunt-Vaeisaelae frequency. Waves are forced at the bottom of the domain, are periodic in the horizontal direction, and form a finite wave packet in the vertical. The results show that the wave packet forms a mean flow that is confined to the interface region that persists long after the wave packet has moved away. Large-amplitude waves are forced to break beneath the interface. (orig.)

  9. Internal Erosion During Soil PipeFlow: State of Science for Experimental and Numerical Analysis

    Science.gov (United States)

    Many field observations have led to speculation on the role of piping in embankment failures, landslides, and gully erosion. However, there has not been a consensus on the subsurface flow and erosion processes involved, and inconsistent use of terms have exacerbated the problem. ...

  10. International technology and knowledge flows and capabilities in building in developing countries

    NARCIS (Netherlands)

    Egmond - de Wilde De Ligny, van E.L.C.; Kumaraswamy, M.M.

    2004-01-01

    Technological innovations in manufacturing were indicated to have an important impact on industry development. Innovation is seen as a cyclic process that includes not only the invention of technologies, but also the diffusion in terms of flows of technologies and knowledge, adoption, application,

  11. Flux schemes based finite volume method for internal transonic flow with condensation

    Czech Academy of Sciences Publication Activity Database

    Halama, Jan; Benkhaldoun, F.; Fořt, J.

    2011-01-01

    Roč. 65, č. 8 (2011), s. 953-968 ISSN 0271-2091 Institutional research plan: CEZ:AV0Z20760514 Keywords : VFFC flux * SRNH flux * two-phase homogeneous flow * fractional step method * condensation Subject RIV: BK - Fluid Dynamics Impact factor: 1.176, year: 2011

  12. International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects

    Science.gov (United States)

    Pueschel, Rudolf F. (Editor)

    1991-01-01

    Following a mandate by the International Aerosol Climatology Program under the auspices of International Association of Meteorology and Atmospheric Physics International Radiation Commission, 45 scientists from five nations convened to discuss relevant issues associated with the measurement, properties, and effects of stratospheric aerosols. A summary is presented of the discussions on formation and evolution, transport and fate, effects on climate, role in heterogeneous chemistry, and validation of lidar and satellite remote sensing of stratospheric aerosols. Measurements are recommended of the natural (background) and the volcanically enhanced aerosol (sulfuric acid and silica particles), the exhaust of shuttle, civil aviation and supersonic aircraft operations (alumina, soot, and ice particles), and polar stratospheric clouds (ice, condensed nitric and hydrochloric acids).

  13. New Media Technology in Developing Effective Organizational Internal Communication

    Directory of Open Access Journals (Sweden)

    Nur Kholisoh

    2017-01-01

    Full Text Available The article was intended to investigate various benefits of Whatsapp Messenger application for an effective intenal communication in PT Euro Management Indonesia. In addition, this research also aimed to map the organizational internal communication pattern through the use of Whatsapp Messenger application. The research used theories of organizaional communication, new media communication pattern, and computer mediated communication (CMC. Moreover, paradigm used in the research was constructivist with qualitative approach and the research method was case study. The research result finds that the use of new media Whatsapp Messenger as a tool of communication can build effective internal communication in PT Euro Management Indonesia. Moreover, it also shows that the internal organizational communication pattern in PT Euro Management Indonesia used in Whatsapp Messenger application is conversation pattern.

  14. The Influence of International Parity on the Exchange Rate: Purchasing Power Parity and International Fisher Effect

    Directory of Open Access Journals (Sweden)

    Oana Mionel

    2012-02-01

    Full Text Available This article assesses the impact of the inflationand interest rates on the exchange rates.The analysis tests the relation between the inflation rate and the exchange rate by applying thePurchasing Power Parity Theory, while the relationbetween the interest rate and the inflation rate istested by applying the International Fisher EffectTheory. In order to test the Purchasing Power Paritythe study takes into account the period of time between 1990 – 2009, and the following countries –the USA, Germany, the UK, Switzerland, Canada, Japan and China. As for testing the InternationalFisher Effect Theory the period of time is the same, 1990 – 2009, but a few countries are different –the USA, Germany, the UK, Switzerland, Canada, Australia and New Zeeland. Thus, both theoriesanalyse the USA as home country.

  15. Effect of aerosolized acetylcholine on bronchial blood flow.

    Science.gov (United States)

    Charan, N B; Carvalho, P; Johnson, S R; Thompson, W H; Lakshminarayan, S

    1998-08-01

    We studied the effects of aerosolized as well as intravenous infusion of acetylcholine on bronchial blood flow in six anesthetized sheep. Intravenous infusion of acetylcholine, at a dose of 2 microg/kg, increased bronchial blood flow from 45 +/- 15 (SE) to 74 +/- 30 ml/min, and vascular conductance increased by 76 +/- 22%. In contrast, aerosolized acetylcholine at doses of 2 and 20 microg/kg decreased bronchial vascular conductance by approximately 10%. At an aerosolized dose of 200 microg/kg, the bronchial vascular conductance increased by approximately 15%, and there was no further increase in conductance when the aerosolized dose was increased to 2,000 microg/kg. Pretreatment of animals with a nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methyl ester hydrochloride, partially blocked the vasodilatory effects of intravenous acetylcholine and completely blocked the vasodilatory effects of high-dose aerosolized acetylcholine. These data suggest that aerosolized acetylcholine does not readily penetrate the vascular wall of bronchial circulatory system and, therefore, has minimal vasodilatory effects on the bronchial vasculature.

  16. Effect of warming and flow rate conditions of blood warmers on red blood cell integrity.

    Science.gov (United States)

    Poder, T G; Pruneau, D; Dorval, J; Thibault, L; Fisette, J-F; Bédard, S K; Jacques, A; Beauregard, P

    2016-11-01

    Fluid warmers are routinely used to reduce the risk of hypothermia and cardiac complications associated with the infusion of cold blood products. However, warming blood products could generate haemolysis. This study was undertaken to compare the impact of temperature of blood warmers on the per cent haemolysis of packed red blood cells (RBCs) heated at different flow rates as well as non-flow conditions. Infusion warmers used were calibrated at 41·5°C ± 0·5°C and 37·5°C ± 0·5°C. Cold RBC units stored at 4°C in AS-3 (n = 30), aged 30-39 days old, were divided into half units before being allocated under two different scenarios (i.e. infusion pump or syringe). Blood warmers were effective to warm cold RBCs to 37·5°C or 41·5°C when used in conjunction with an infusion pump at flow rate up to 600 ml/h. However, when the warmed blood was held in a syringe for various periods of time, such as may occur in neonatal transfusions, the final temperature was below the expected requirements with measurement as low as 33·1°C. Increasing the flow with an infusion pump increased haemolysis in RBCs from 0·2% to up to 2·1% at a flow rate of 600 ml/h regardless of the warming device used (P < 0·05). No relevant increase of haemolysis was observed using a syringe. The use of a blood warmer adjusted to 41·5°C is probably the best choice for reducing the risk of hypothermia for the patient without generating haemolysis. However, we should be cautious with the use of an infusion pump for RBC transfusion, particularly at high flow rates. © 2016 International Society of Blood Transfusion.

  17. Cross-coupling effects in chemically non-equilibrium viscous compressible flows

    International Nuclear Information System (INIS)

    Kustova, E.V.; Giordano, D.

    2011-01-01

    Graphical abstract: Self-cosistent kinetic-theory description of chemical-reaction rates and mean normal stress in one-temperature viscous compressible gas flows. Reaearch highlights: → In chemically non-equilibrium viscous compressible flows, the rate of each reaction depends on the velocity divergence and rates of all other reactions. → Cross effects between the rates of chemical reactions and normal mean stress can be found in the symmetric form and expressed in terms of the reaction affinities. → In the case of small affinities, the entropy production is unconditionally non-negative; in the case of finite affinities, the entropy production related to the scalar forces has no definite sign. - Abstract: A closed self-consistent description of a one-temperature non-equilibrium reacting flow is presented on the basis of the kinetic theory methods. A general case including internal degrees of freedom, dissociation-recombination and exchange reactions, and arbitrary values of affinities of chemical reactions is considered. Chemical-reaction rates and mean normal stress in viscous compressible flows are studied and a symmetric cross coupling between these terms is found. It is shown that the rate of each chemical reaction and the mean normal stress depend on velocity divergence and affinities of all chemical reactions; the law of mass action is violated in viscous flows. The results obtained in the frame of linear irreversible thermodynamics can be deduced from the proposed model for the particular case of small affinities. The reciprocal Onsager-Casimir relations are verified, the symmetry of kinetic coefficients is demonstrated, and the entropy production in a viscous flow is studied.

  18. The Influence of International Parity on the Exchange Rate: Purchasing Power Parity and International Fisher Effect

    OpenAIRE

    Oana Mionel

    2012-01-01

    This article assesses the impact of the inflation and interest rates on the exchange rates. The analysis tests the relation between the inflation rate and the exchange rate by applying the Purchasing Power Parity Theory, while the relation between the interest rate and the inflation rate is tested by applying the International Fisher Effect Theory. In order to test the Purchasing Power Parity the study takes into account the period of time between 1990 – 2009, and the following countries – th...

  19. International programme to mitigate the health effects of the Chernobyl accident: Establishment of an international centre

    International Nuclear Information System (INIS)

    1990-11-01

    In April 1990, an agreement was signed between the WHO and the USSR Ministry of Health to set up a long-term international programme to assist the populations affected by the Chernobyl accident, as well as to increase the body of scientific knowledge about radiation effects. This report outlines the contents of the agreement and describes the action taken by the WHO to implement the programme

  20. Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Seung Hwa; Lee, Su Ryong; Lee, Choong Hoon [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2015-01-15

    The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100 .deg .C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100 .deg. C.

  1. Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

    International Nuclear Information System (INIS)

    Yeo, Seung Hwa; Lee, Su Ryong; Lee, Choong Hoon

    2015-01-01

    The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100 .deg .C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100 .deg. C.

  2. Significance of preoperative cerebral blood flow measurements in endovascular occlusion of the internal carotid and middle cerebral arteries

    International Nuclear Information System (INIS)

    Laurent, A.; Weitzner, I.; Luft, A.; Merland, J.J.

    1988-01-01

    Cerebral blood flow (CBF) measurements during 12 endovascular balloon occlusions (ten internal carotid and two middle cerebral arteries) with good clinical and angiographic tolerance were done with repeated boluses of Xe-133 injected directly into the ipsi- and contralateral carotid systems, during the occlusion and repeated measurements with detectors on both sides (before occlusion and 5-30 minutes after occlusion). In two cases of unchanged and four of increased CBF, one reversible deficit was probably due to an embolus. In six cases of decreased CBF, two deficits occurred, characterized by a greater than 25% decrease. It seems to represent a good predictive value for intolerance to occlusion

  3. The effect of magnetohydrodynamic nano fluid flow through porous cylinder

    Science.gov (United States)

    Widodo, Basuki; Arif, Didik Khusnul; Aryany, Deviana; Asiyah, Nur; Widjajati, Farida Agustini; Kamiran

    2017-08-01

    This paper concerns about the analysis of the effect of magnetohydrodynamic nano fluid flow through horizontal porous cylinder on steady and incompressible condition. Fluid flow is assumed opposite gravity and induced by magnet field. Porous cylinder is assumed had the same depth of porous and was not absorptive. The First thing to do in this research is to build the model of fluid flow to obtain dimentional governing equations. The dimentional governing equations are consist of continuity equation, momentum equation, and energy equation. Furthermore, the dimensional governing equations are converted to non-dimensional governing equation by using non-dimensional parameters and variables. Then, the non-dimensional governing equations are transformed into similarity equations using stream function and solved using Keller-Box method. The result of numerical solution further is obtained by taking variation of magnetic parameter, Prandtl number, porosity parameter, and volume fraction. The numerical results show that velocity profiles increase and temperature profiles decrease when both of the magnetic and the porosity parameter increase. However, the velocity profiles decrease and the temperature profiles increase when both of the magnetic and the porosity parameter increase.

  4. Internal risks of factoring business: identification, cause-effect relationships, accounting and management aspects

    Directory of Open Access Journals (Sweden)

    I.M. Vygivska

    2017-12-01

    Full Text Available The article identifies the risks of the economic activity of a factoring company. The identified risks are divided into internal (fraud risk, credit risk, liquidity, nonpayment, staff, supplier's failure to meet the terms of the supply / factoring contract and external (legal, inflation, currency, interest, industry risks, country risk. The cause-effect relationships of the identified risks have been established. The content of information requests of the leading part of the factoring company, as well as the management subsystems (accounting, economic analysis, control and planning, and the direction of information flows between them (to manage the company's internal risks is determined. These proposals contribute to the improvement of accounting and analytical support for risk management of the factoring business, the choice of alternative risk management methods, the impact on their possible consequences, minimizing the negative impact of risks on the financial condition of the company, and establishing the effectiveness of factoring operations under risk.

  5. Effects of structure parameters on flow and cavitation characteristics within control valve of fuel injector for modern diesel engine

    International Nuclear Information System (INIS)

    Wang, Chao; Li, Guo-Xiu; Sun, Zuo-Yu; Wang, Lan; Sun, Shu-Ping; Gu, Jiao-Jiao; Wu, Xiao-Jun

    2016-01-01

    Highlights: • The Schnerr-Sauer model was used to calculate the cavitation source term. • The development process and influencing factors of cavitation were studied. • The flow process inside control valve during the ball valve opened were studied. • The effects of the structure parameters of the control valve on the cavitation and flow were studied. - Abstract: Cavitation is a common phenomenon in diesel injector and has a strong influence on the internal flow. However, studies so far have focused on cavitation characteristics inside the nozzle. Its influence on the flow during control valve opening remains still unclear. In the paper, a computational study focused on the flow and cavitation phenomena within control valve has been reported and the effects of control valve’s structure parameters (including rounded edge, seal cone angle and outflowing control-orifice structure) on the flow and cavitation characteristics have been investigated in detail. Firstly the 3D model has been validated in terms of single injection quantity and fuel injection duration, showing a good consistency. And then, the development from sheet cavitation to cloud cavitation and the relationship between cavitation, pressure and velocity has been discussed. Based on the numerical results obtained, it is shown that not only the variation of pressure but also the velocity is the important factor which affects cavitation. The increase of the flow velocity reduces the pressure within the flow field which can aggravate the development of cavitation. As cavitation region increases, the fuel flow is hindered and the flow velocity decreases. However, the decrease of flow velocity has suppressed the development of cavitation. All of those variations form a cyclical process.

  6. Experimental effect of flow depth on ratio discharge in lateral intakes in river bend

    International Nuclear Information System (INIS)

    Masjedi, A; Foroushani, E P

    2012-01-01

    Open-channel dividing flow is characterized by the inflow and outflow discharges, the upstream and downstream water depths, and the recirculation flow in the branch channel. In general, diversion flow can be categorized as natural and artificial flow. Natural flow diversion usually occurs as braiding or cut-off in bend rivers, while artificial flow is man-made to divert flow by lateral intake channels for water supply. This study presents the results of a laboratory research into effect intake flow depth on ratio discharge in lateral intakes in 180 degree bend. Investigation on lateral intake and determination of intake flow depth is among the most important issues in lateral intake on ratio discharge with model intake flow depth were measured in a laboratory flume under clear-water. Experiments were conducted for various intake flow depths and with different discharges. It was found that by increasing the flow depth at 180 degree flume bend, ratio discharge increases.

  7. Effective International Medical Disaster Relief: A Qualitative Descriptive Study.

    Science.gov (United States)

    Broby, Nicolette; Lassetter, Jane H; Williams, Mary; Winters, Blaine A

    2018-04-01

    Purpose The aim of this study was to assist organizations seeking to develop or improve their medical disaster relief effort by identifying fundamental elements and processes that permeate high-quality, international, medical disaster relief organizations and the teams they deploy. A qualitative descriptive design was used. Data were gathered from interviews with key personnel at five international medical response organizations, as well as during field observations conducted at multiple sites in Jordan and Greece, including three refugee camps. Data were then reviewed by the research team and coded to identify patterns, categories, and themes. The results from this qualitative, descriptive design identified three themes which were key characteristics of success found in effective, well-established, international medical disaster relief organizations. These characteristics were first, ensuring an official invitation had been extended and the need for assistance had been identified. Second, the response to that need was done in an effective and sustainable manner. Third, effective organizations strived to obtain high-quality volunteers. By following the three key characteristics outlined in this research, organizations are more likely to improve the efficiency and quality of their work. In addition, they will be less likely to impede the overall recovery process. Broby N , Lassetter JH , Williams M , Winters BA . Effective international medical disaster relief: a qualitative descriptive study. Prehosp Disaster Med. 2018;33(2):119-126.

  8. Effectiveness and legitimacy in international law / Christian Tomuschat

    Index Scriptorium Estoniae

    Tomuschat, Christian

    2017-01-01

    Suveräänsusest ja rahvusvahelistest suhetest rahvusvahelise õigus aspektist. Autori ettekanne tema 80. juubeli auks peetud sümpoosionil „Effectiveness and Legitimacy of International Law” (Speyer, 22.-23. juulil 2016). Sama teema käsitlusi artiklites erinevatelt autoritelt lk. 321-408

  9. Nonlinear throughflow and internal heating effects on vibrating porous medium

    Directory of Open Access Journals (Sweden)

    Palle Kiran

    2016-06-01

    Full Text Available The effect of vertical throughflow and internal heating effects on fluid saturated porous medium under gravity modulation is investigated. The amplitude of modulation is considered to be very small and the disturbances are expanded in terms of power series of amplitude of convection. A weakly nonlinear stability analysis is proposed to study stationary convection. The Nusselt number is obtained numerically to present the results of heat transfer while using Ginzburg–Landau equation. The vertical throughflow has dual effect either to destabilize or to stabilize the system for downward or upward directions. The effect of internal heat source (Ri>0 enhances or sink (Ri<0 diminishes heat transfer in the system. The amplitude and frequency of modulation have the effects of increasing or diminishing heat transport. For linear model Venezian approach suggested that throughflow and internal heating have both destabilizing and stabilizing effects for suitable ranges of Ω. Further, the study establishes that heat transport can be controlled effectively by a mechanism that is external to the system throughflow and gravity modulation.

  10. Development assistance for health: past trends, associations, and the future of international financial flows for health.

    Science.gov (United States)

    Dieleman, Joseph L; Schneider, Matthew T; Haakenstad, Annie; Singh, Lavanya; Sadat, Nafis; Birger, Maxwell; Reynolds, Alex; Templin, Tara; Hamavid, Hannah; Chapin, Abigail; Murray, Christopher J L

    2016-06-18

    Disbursements of development assistance for health (DAH) have risen substantially during the past several decades. More recently, the international community's attention has turned to other international challenges, introducing uncertainty about the future of disbursements for DAH. We collected audited budget statements, annual reports, and project-level records from the main international agencies that disbursed DAH from 1990 to the end of 2015. We standardised and combined records to provide a comprehensive set of annual disbursements. We tracked each dollar of DAH back to the source and forward to the recipient. We removed transfers between agencies to avoid double-counting and adjusted for inflation. We classified assistance into nine primary health focus areas: HIV/AIDS, tuberculosis, malaria, maternal health, newborn and child health, other infectious diseases, non-communicable diseases, Ebola, and sector-wide approaches and health system strengthening. For our statistical analysis, we grouped these health focus areas into two categories: MDG-related focus areas (HIV/AIDS, tuberculosis, malaria, child and newborn health, and maternal health) and non-MDG-related focus areas (other infectious diseases, non-communicable diseases, sector-wide approaches, and other). We used linear regression to test for structural shifts in disbursement patterns at the onset of the Millennium Development Goals (MDGs; ie, from 2000) and the global financial crisis (impact estimated to occur in 2010). We built on past trends and associations with an ensemble model to estimate DAH through the end of 2040. In 2015, US$36·4 billion of DAH was disbursed, marking the fifth consecutive year of little change in the amount of resources provided by global health development partners. Between 2000 and 2009, DAH increased at 11·3% per year, whereas between 2010 and 2015, annual growth was just 1·2%. In 2015, 29·7% of DAH was for HIV/AIDS, 17·9% was for child and newborn health, and 9·8

  11. Introduction to the special issue 'unintended effects of international cooperation'.

    Science.gov (United States)

    Koch, Dirk-Jan; Schulpen, Lau

    2018-06-01

    The 'Evaluation and Program Planning' journal has contributed to the launch of an academic discussion of unintended effects of international cooperation, notably by publishing in 2016 articles by Bamberger, Tarsilla, & Hesse-Biber and by Jabeen. This special issue aims to take up the academic challenges as laid down by those authors, by providing among others a clear typology and applying it, by outlining various methodological options and testing them, and elaborating on suggestions on how to deal with the barriers that prevent unintended effects being taken into account. This special issue makes clear that it is possible to reduce the share of unforeseen effects of international cooperation. Turning the spotlight on unintended effects that can be anticipated, and aiming to make progress on uncovering those that are particularly difficult to detect and debunking those that are exaggerated is the task that lies ahead of us. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Analytical effective tensor for flow-through composites

    Science.gov (United States)

    Sviercoski, Rosangela De Fatima [Los Alamos, NM

    2012-06-19

    A machine, method and computer-usable medium for modeling an average flow of a substance through a composite material. Such a modeling includes an analytical calculation of an effective tensor K.sup.a suitable for use with a variety of media. The analytical calculation corresponds to an approximation to the tensor K, and follows by first computing the diagonal values, and then identifying symmetries of the heterogeneity distribution. Additional calculations include determining the center of mass of the heterogeneous cell and its angle according to a defined Cartesian system, and utilizing this angle into a rotation formula to compute the off-diagonal values and determining its sign.

  13. Effects of couple stresses in MHD channel flow

    International Nuclear Information System (INIS)

    Soundalgekar, V.M.; Aranake, R.N.

    1977-01-01

    An analysis of fully developed MHD channel flow of an electrically conducting incompressible fluid, taking into account the couple stresses, is carried out. Exact solutions are derived for velocity profiles, current density, skin-friction and coefficient of mass flux. They are influenced by the magnetic field, the loading parameter k, and the non-dimensional parameter (a=b 1 /lambda). Their variations with respect to M, k and a are represented graphically, this is followed by a physical discussion. It is observed that the couple stresses are more effective in the presence of a very weak magnetic field. (Auth.)

  14. Virtual mass effects in two-phase flow. Topical report

    International Nuclear Information System (INIS)

    Cheng, L.Y.; Drew, D.A.; Lahey, R.T. Jr.

    1978-03-01

    The effect of virtual mass on phase separation during the acceleration of a two-phase mixture was studied. Virtual mass can be regarded as an induced inertia on the dispersed phase which is accelerating relative to the continuous phase, and it was found that the virtual mass acceleration is objective, implying an invariance with respect to reference frame. An objective form of the virtual acceleration was derived and required parameters were determined for limiting cases. Analyses determined that experiments on single bubble nozzle/diffuser flow cannot readily discriminate between various virtual mass acceleration models

  15. Effect of asynchrony on numerical simulations of fluid flow phenomena

    Science.gov (United States)

    Konduri, Aditya; Mahoney, Bryan; Donzis, Diego

    2015-11-01

    Designing scalable CFD codes on massively parallel computers is a challenge. This is mainly due to the large number of communications between processing elements (PEs) and their synchronization, leading to idling of PEs. Indeed, communication will likely be the bottleneck in the scalability of codes on Exascale machines. Our recent work on asynchronous computing for PDEs based on finite-differences has shown that it is possible to relax synchronization between PEs at a mathematical level. Computations then proceed regardless of the status of communication, reducing the idle time of PEs and improving the scalability. However, accuracy of the schemes is greatly affected. We have proposed asynchrony-tolerant (AT) schemes to address this issue. In this work, we study the effect of asynchrony on the solution of fluid flow problems using standard and AT schemes. We show that asynchrony creates additional scales with low energy content. The specific wavenumbers affected can be shown to be due to two distinct effects: the randomness in the arrival of messages and the corresponding switching between schemes. Understanding these errors allow us to effectively control them, rendering the method's feasibility in solving turbulent flows at realistic conditions on future computing systems.

  16. Technological effect of vibroprocessing by flows of organic granular media

    Science.gov (United States)

    Lebedev, V. A.; Shishkina, A. P.; Davydova, I. V.; Morozova, A. V.

    2018-03-01

    The analysis of approaches to modeling of vibrational processing by granulated media is carried out. The vibroprocessing model which provides effective finishing of the surfaces of the parts due to the stone fruit organic media granules is developed. The model is based on the granule flow energy impact on the surface being treated. As the main characteristic of the organic media processing, a specific volumetric metal scrap is used, the physical meaning of which is the increase rate in the thickness of the material removed from the surface at a given velocity and pressure of the medium. It is shown that the metal scrap depends on the medium flow velocity, the height of the loading column of the granular medium, and the conditions for the formation of a medium stationary circulation motion. Based on the analysis of the results of experimental studies of the influence of amplitude-frequency characteristics on the removal of metal in the process of vibroprocessing with abrasive granules, the dependence of the specific volume metal removal is proposed for organic media processing, taking into account the threshold amplitude and frequency of oscillations of the working chamber, at which the effect of surface treatment is observed. The established set of relationships describing the effective conditions for vibroprocessing with stone organic media was obtained using experimental data, which allows us to assume that the model obtained is valid.

  17. 3rd International Conference on Micro and Nano Flows (MNF2011)

    CERN Document Server

    Koenig, Carola; Micro and Nano Flow Systems for Bioanalysis

    2013-01-01

    Micro and Nano Flow Systems for Bioanalysis addresses the latest developments in biomedical engineering at very small scales. It shows how organic systems require multi-scale understanding in the broadest sense whether the approach  is experimental or mathematical, and whether the physiological state is healthy or diseased. Micro-and nano-fluidics represent  key areas of translational research in which state-of-the-art engineering processes and devices are applied to bedside monitoring and treatment. By applying conventional micro- and nano-engineering to complex organic solids, fluids, and their interactions, leading researchers from throughout the world describe methods and techniques with great potential for use in medicine and clinical practice. Coverage includes the seeming plethora of new, fine-scale optical methods for measuring blood flow as well as endothelial activation and interaction with tissue. Generic areas of modeling and bioelectronics are also considered. In keeping with the recurring them...

  18. Stratified charge rotary engine - Internal flow studies at the MSU engine research laboratory

    Science.gov (United States)

    Hamady, F.; Kosterman, J.; Chouinard, E.; Somerton, C.; Schock, H.; Chun, K.; Hicks, Y.

    1989-01-01

    High-speed visualization and laser Doppler velocimetry (LDV) systems consisting of a 40-watt copper vapor laser, mirrors, cylindrical lenses, a high speed camera, a synchronization timing system, and a particle generator were developed for the study of the fuel spray-air mixing flow characteristics within the combustion chamber of a motored rotary engine. The laser beam is focused down to a sheet approximately 1 mm thick, passing through the combustion chamber and illuminates smoke particles entrained in the intake air. The light scattered off the particles is recorded by a high speed rotating prism camera. Movies are made showing the air flow within the combustion chamber. The results of a movie showing the development of a high-speed (100 Hz) high-pressure (68.94 MPa, 10,000 psi) fuel jet are also discussed. The visualization system is synchronized so that a pulse generated by the camera triggers the laser's thyratron.

  19. Flow structure and heat exchange analysis in internal cooling channel of gas turbine blade

    Science.gov (United States)

    Szwaba, Ryszard; Kaczynski, Piotr; Doerffer, Piotr; Telega, Janusz

    2016-08-01

    This paper presents the study of the flow structure and heat transfer, and also their correlations on the four walls of a radial cooling passage model of a gas turbine blade. The investigations focus on heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillet, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which possesses very realistic features.

  20. Numerical simulation of wall roughness effects in cavitating flow

    Energy Technology Data Exchange (ETDEWEB)

    Echouchene, F. [Laboratoire d' electronique et de microelectronique, Departement de Physique, Faculte des Sciences de Monastir, 5000 (Tunisia); Belmabrouk, H., E-mail: frchouchene@yahoo.fr [Laboratoire d' electronique et de microelectronique, Departement de Physique, Faculte des Sciences de Monastir, 5000 (Tunisia); Le Penven, L.; Buffat, M. [LMFA UMR CNRS 5509, Universite de Claude Bernard Lyon 1, Ecole Centrale de Lyon, INSA de Lyon (France)

    2011-10-15

    Hydrodynamic cavitation has an important effect on the performance of Diesel injectors. It influences the nature of the fuel spray and the efficiency of the combustion process. In the present study, we investigate numerically the effect of wall roughness in the cavitating and turbulent flow developing inside a Diesel injector. The mixture model based on a single fluid is adopted and the commercial Fluent software is used to solve the transport equations. The discharge coefficient C{sub d} is computed for different cavitation numbers and wall roughness heights. Profiles of density mixture, vapor volume fraction, mean velocity and turbulent kinetic energy are reported. The effects of wall roughness and injection pressure are analyzed.

  1. Three dimensional PNS solutions of hypersonic internal flows with equilibrium chemistry

    Science.gov (United States)

    Liou, May-Fun

    1989-01-01

    An implicit procedure for solving parabolized Navier-Stokes equations under the assumption of a general equation of state for a gas in chemical equilibrium is given. A general and consistent approach for the evaluation of Jacobian matrices in the implicit operator avoids the use of unnecessary auxiliary quantities and approximations, and leads to a simple expression. Applications to two- and three-dimensional flow problems show efficiency in computer time and economy in storage.

  2. Large-Eddy Simulation of Internal Flow through Human Vocal Folds

    Science.gov (United States)

    Lasota, Martin; Šidlof, Petr

    2018-06-01

    The phonatory process occurs when air is expelled from the lungs through the glottis and the pressure drop causes flow-induced oscillations of the vocal folds. The flow fields created in phonation are highly unsteady and the coherent vortex structures are also generated. For accuracy it is essential to compute on humanlike computational domain and appropriate mathematical model. The work deals with numerical simulation of air flow within the space between plicae vocales and plicae vestibulares. In addition to the dynamic width of the rima glottidis, where the sound is generated, there are lateral ventriculus laryngis and sacculus laryngis included in the computational domain as well. The paper presents the results from OpenFOAM which are obtained with a large-eddy simulation using second-order finite volume discretization of incompressible Navier-Stokes equations. Large-eddy simulations with different subgrid scale models are executed on structured mesh. In these cases are used only the subgrid scale models which model turbulence via turbulent viscosity and Boussinesq approximation in subglottal and supraglottal area in larynx.

  3. Large-Eddy Simulation of Internal Flow through Human Vocal Folds

    Directory of Open Access Journals (Sweden)

    Lasota Martin

    2018-01-01

    Full Text Available The phonatory process occurs when air is expelled from the lungs through the glottis and the pressure drop causes flow-induced oscillations of the vocal folds. The flow fields created in phonation are highly unsteady and the coherent vortex structures are also generated. For accuracy it is essential to compute on humanlike computational domain and appropriate mathematical model. The work deals with numerical simulation of air flow within the space between plicae vocales and plicae vestibulares. In addition to the dynamic width of the rima glottidis, where the sound is generated, there are lateral ventriculus laryngis and sacculus laryngis included in the computational domain as well. The paper presents the results from OpenFOAM which are obtained with a large-eddy simulation using second-order finite volume discretization of incompressible Navier-Stokes equations. Large-eddy simulations with different subgrid scale models are executed on structured mesh. In these cases are used only the subgrid scale models which model turbulence via turbulent viscosity and Boussinesq approximation in subglottal and supraglottal area in larynx.

  4. Exchange Rate Effects on International Commercial Trade Competitiveness

    Directory of Open Access Journals (Sweden)

    Ionel Bostan

    2018-04-01

    Full Text Available This study is meant to be an evaluation sustained by theoretical and empirical considerations of the exchange rate impact on international commercial trade competitiveness. In this respect, the study aims to find how the exchange rate influences Romanian competitiveness through assessing the effects generated on exports and imports. The main purpose of the study is to assess the complex action of the exchange rate on international commercial trade competitiveness in contemporaneity and the connections between these variables. The empirical part contains a regression analysis where exports and imports are dependent variables influenced by a series of determinants.

  5. Internal Flow Management in a Multi-Zone Climate Control Unit

    NARCIS (Netherlands)

    Persis, C. De; Jessen, J.J.; Izadi-Zamanabadi, R.; Schiøler, H.

    2006-01-01

    In this contribution, we examine a dynamic model describing the evolution of internal climate conditions in a closed environment partitioned into zones for which different climate conditions must be guaranteed. The zones are not separated, large air masses are exchanged among them, and the behavior

  6. Internal flow management in a multi-zone climate control unit

    DEFF Research Database (Denmark)

    De Persis, C.; Jessen, Jan Jacob; Izadi-Zamanabadi, Roozbeh

    2006-01-01

    In this contribution, we examine a dynamic model describing the evolution of internal climate conditions in a closed environment partitioned into zones for which different climate conditions must be guaranteed. The zones are not separated, large air masses are exchanged among them, and the behavior...

  7. Report on the 4th International Conference on monitoring, simulation, prevention and remediation of dense and debris flows - Debris Flow 2012

    Directory of Open Access Journals (Sweden)

    Daniele de Wrachien

    2012-09-01

    Full Text Available Debris and hyper-concentrated flows are amongst the most destructive of all water-related disasters. These hazards are likely to become more frequent and more important in the future due to the effects of the increase in population, urbanization, land subsidence and the impact of climate change. They affect both rural and urban environments, particularly in river basins and in mountain areas. In recent years, they have attracted more and more attention from the scientific and professional communities due to the number of lives lost, and there is growing public concern for the future. New methods and measures are required to cope with debris flow changes and to achieve a harmonious balance between the environment and economic forces.

  8. Effective slip lengths for flows over surfaces with nanobubbles: the effects of finite slip

    International Nuclear Information System (INIS)

    Hendy, S C; Lund, N J

    2009-01-01

    We consider effective slip lengths for flows of simple liquids over surfaces contaminated by gaseous nanobubbles. In particular, we examine whether the effects of finite slip over the liquid-bubble interface are important in limiting effective slip lengths over such surfaces. Using an expression that interpolates between the perfect slip and finite slip regimes for flow over bubbles, we conclude that for the bubble dimensions and coverages typically reported in the literature the effects of finite slip are secondary, reducing effective slip lengths by only 10%. Further, we find that nanobubbles do not significantly increase slip lengths beyond those reported for bare hydrophobic surfaces.

  9. Effect Of Steel Flow Control Devices On Flow And Temperature Field In The Tundish Of Continuous Casting Machine

    Directory of Open Access Journals (Sweden)

    Sowa L.

    2015-06-01

    Full Text Available The mathematical model and numerical simulations of the liquid steel flow in a tundish are presented in this paper. The problem was treated as a complex and solved by the finite element method. One takes into consideration in the mathematical model the changes of thermophysical parameters depending on the temperature. The single-strand tundish is used to casting slabs. The internal work space of the tundish was modified by flow control devices. The first device was a pour pad situated in the pouring tundish zone. The second device was a dam. The third device was a baffle with three holes. The dam and baffle were placed in the tundish at different positions depending on the variant. The main purpose of using these was to put barriers in the steel flow path as well as give directional metal flow upwards which facilitated inclusion floatation. The interaction of flow control devices on hydrodynamic conditions was received from numerical simulations. As a result of the computations carried out, the liquid steel flow and steel temperature fields were obtained. The influences of the tundish modifications on the velocity fields in liquid phase of the steel were estimated, because these have essential an influence on high-quality of a continuous steel cast slab.

  10. Informing the public on technical effectiveness of international safeguards

    International Nuclear Information System (INIS)

    Hunt, H.M.

    1994-01-01

    In recent years, public interest regarding IAEA (International Atomic Energy Agency) safeguards effectiveness has partially shifted to detection of undeclared nuclear facilities. Nevertheless, important segments of the public remain vitally interested in whether international safeguards would be able to reliably and definitively detect diversion of bomb quantities of plutonium or highly enriched uranium from open-quotes bulk handlingclose quotes facilities. There now exists a sizable body of unclassified technical reports, based on experimental results over many years, written by various experts, describing actual capabilities and limitations of safeguards techniques and systems, which collectively lead to definitive evaluations of technical safeguards effectiveness. For a large-scale operation of spent fuel reprocessing, plutonium fuel fabrication, or gas centrifuge uranium enrichment, an undisputable conclusion is that international safeguards systems would be unable to reliably and definitively detect the diversion in a one-year period of a significant quantity of plutonium or enriched uranium; moreover, diversion of many significant quantities per year (from such an operation) would have negligible probability of definitive detection if conducted in accordance with particle diversion scenarios. To properly inform the public and government agencies, reports on technical effectiveness of international safeguards should incorporate these basic conclusions

  11. Hall effects on hydromagnetic Couette flow of Class-II in a rotating ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... Couette flow of class-II of a viscous, incompressible and electrically conducting fluid with ... Numerical solution of energy equation and numerical values of rate of heat transfer at ...

  12. Thermal convection in a toroidal duct of a liquid metal blanket. Part II. Effect of axial mean flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xuan, E-mail: xuanz@umich.edu; Zikanov, Oleg

    2017-03-15

    Highlights: • 2D convection flow develops with internal heating and strong axial magnetic field. • The flow is strongly modified by the buoyancy force associated with growing T{sub m}. • Thermal convection is suppressed at high Gr. • High temperature difference between top and bottom walls is expected at high Gr. - Abstract: The work continues the exploration of the effect of thermal convection on flows in toroidal ducts of a liquid metal blanket. This time we consider the effect of the mean flow along the duct and of the associated heat transfer diverting the heat deposited by captured neutrons. Numerical simulations are conducted for a model system with two-dimensional (streamwise-uniform) fully developed flow, purely toroidal magnetic field, and perfectly electrically and thermally insulating walls. Realistically high Grashof (up to 10{sup 11}) and Reynolds (up to 10{sup 6}) numbers are used. It is found that the flow develops thermal convection in the transverse plane at moderate Grashof numbers. At large Grashof numbers, the flow is dominated by the top-bottom asymmetry of the streamwise velocity and stable stratification of temperature, which are caused by the buoyancy force due to the mean temperature growing along the duct. This leads to suppression of thermal convection, weak mixing, and substantial gradients of wall temperature. Further analysis based on more realistic models is suggested.

  13. Effect of EHR user interface changes on internal prescription discrepancies.

    Science.gov (United States)

    Turchin, A; Sawarkar, A; Dementieva, Y A; Breydo, E; Ramelson, H

    2014-01-01

    To determine whether specific design interventions (changes in the user interface (UI)) of an electronic health record (EHR) medication module are associated with an increase or decrease in the incidence of contradictions between the structured and narrative components of electronic prescriptions (internal prescription discrepancies). We performed a retrospective analysis of 960,000 randomly selected electronic prescriptions generated in a single EHR between 01/2004 and 12/2011. Internal prescription discrepancies were identified using a validated natural language processing tool with recall of 76% and precision of 84%. A multivariable autoregressive integrated moving average (ARIMA) model was used to evaluate the effect of five UI changes in the EHR medication module on incidence of internal prescription discrepancies. Over the study period 175,725 (18.4%) prescriptions were found to have internal discrepancies. The highest rate of prescription discrepancies was observed in March 2006 (22.5%) and the lowest in March 2009 (15.0%). Addition of "as directed" option to the dropdown decreased prescription discrepancies by 195 / month (p = 0.0004). An non-interruptive alert that reminded providers to ensure that structured and narrative components did not contradict each other decreased prescription discrepancies by 145 / month (p = 0.03). Addition of a "Renew / Sign" button to the Medication module (a negative control) did not have an effect in prescription discrepancies. Several UI changes in the electronic medication module were effective in reducing the incidence of internal prescription discrepancies. Further research is needed to identify interventions that can completely eliminate this type of prescription error and their effects on patient outcomes.

  14. Effect of EHR User Interface Changes on Internal Prescription Discrepancies

    Science.gov (United States)

    Sawarkar, A.; Dementieva, Y.A.; Breydo, E.; Ramelson, H.

    2014-01-01

    Summary Objective To determine whether specific design interventions (changes in the user interface (UI)) of an electronic health record (EHR) medication module are associated with an increase or decrease in the incidence of contradictions between the structured and narrative components of electronic prescriptions (internal prescription discrepancies). Materials and Methods We performed a retrospective analysis of 960,000 randomly selected electronic prescriptions generated in a single EHR between 01/2004 and 12/2011. Internal prescription discrepancies were identified using a validated natural language processing tool with recall of 76% and precision of 84%. A multivariable autoregressive integrated moving average (ARIMA) model was used to evaluate the effect of five UI changes in the EHR medication module on incidence of internal prescription discrepancies. Results Over the study period 175,725 (18.4%) prescriptions were found to have internal discrepancies. The highest rate of prescription discrepancies was observed in March 2006 (22.5%) and the lowest in March 2009 (15.0%). Addition of „as directed“ option to the dropdown decreased prescription discrepancies by 195 / month (p = 0.0004). An non-interruptive alert that reminded providers to ensure that structured and narrative components did not contradict each other decreased prescription discrepancies by 145 / month (p = 0.03). Addition of a „Renew / Sign“ button to the Medication module (a negative control) did not have an effect in prescription discrepancies. Conclusions Several UI changes in the electronic medication module were effective in reducing the incidence of internal prescription discrepancies. Further research is needed to identify interventions that can completely eliminate this type of prescription error and their effects on patient outcomes. PMID:25298811

  15. Internal and External Imagery Effects on Tennis Skills Among Novices.

    Science.gov (United States)

    Dana, Amir; Gozalzadeh, Elmira

    2017-10-01

    The purpose of this study was to determine the effects of internal and external visual imagery perspectives on performance accuracy of open and closed tennis skills (i.e., serve, forehand, and backhand) among novices. Thirty-six young male novices, aged 15-18 years, from a summer tennis program participated. Following initial skill acquisition (12 sessions), baseline assessments of imagery ability and imagery perspective preference were used to assign participants to one of three groups: internal imagery ( n = 12), external imagery ( n = 12), or a no-imagery (mental math exercise) control group ( n = 12). The experimental interventions of 15 minutes of mental imagery (internal or external) or mental math exercises followed by 15 minutes of physical practice were held three times a week for six weeks. The performance accuracy of the groups on the serve, forehand, and backhand strokes was measured at pre- and post-test using videotaping. Results showed significant increases in the performance accuracy of all three tennis strokes in all three groups, but serve accuracy in the internal imagery group and forehand accuracy in the external imagery group showed greater improvements, while backhand accuracy was similarly improved in all three groups. These findings highlight differential efficacy of internal and external visual imagery for performance improvement on complex sport skills in early stage motor learning.

  16. International Collaboration Patterns and Effecting Factors of Emerging Technologies

    Science.gov (United States)

    Bai, Xu; Liu, Yun

    2016-01-01

    With the globalization of the world economy, international innovation collaboration has taken place all over the world. This study selects three emerging technologies (3D printing, big data and carbon nanotubes and graphene technology) among 20 countries as the research objects, using three patent-based indicators and network relationship analysis to reflect international collaboration patterns. Then we integrate empirical analyses to show effecting factors of international collaboration degrees by using panel data. The results indicate that while 3D printing technology is associated with a “balanced collaboration” mode, big data technology is more accurately described by a radial pattern, centered on the United States, and carbon nanotubes and graphene technology exhibits “small-world” characteristics in this respect. It also shows that the factors GDP per capita (GPC), R&D expenditure (RDE) and the export of global trade value (ETV) negatively affect the level of international collaboration. It could be useful for China and other developing countries to make international scientific and technological collaboration strategies and policies in the future. PMID:27911926

  17. International Collaboration Patterns and Effecting Factors of Emerging Technologies.

    Directory of Open Access Journals (Sweden)

    Xu Bai

    Full Text Available With the globalization of the world economy, international innovation collaboration has taken place all over the world. This study selects three emerging technologies (3D printing, big data and carbon nanotubes and graphene technology among 20 countries as the research objects, using three patent-based indicators and network relationship analysis to reflect international collaboration patterns. Then we integrate empirical analyses to show effecting factors of international collaboration degrees by using panel data. The results indicate that while 3D printing technology is associated with a "balanced collaboration" mode, big data technology is more accurately described by a radial pattern, centered on the United States, and carbon nanotubes and graphene technology exhibits "small-world" characteristics in this respect. It also shows that the factors GDP per capita (GPC, R&D expenditure (RDE and the export of global trade value (ETV negatively affect the level of international collaboration. It could be useful for China and other developing countries to make international scientific and technological collaboration strategies and policies in the future.

  18. Effects of tempering on internal friction of carbon steels

    International Nuclear Information System (INIS)

    Hoyos, J.J.; Ghilarducci, A.A.; Salva, H.R.; Chaves, C.A.; Velez, J.M.

    2011-01-01

    Research highlights: → Time tempering dependent microstructure of two steels is studied by internal friction. → Internal friction indicates the interactions of dislocations with carbon and carbides. → Internal friction detects the first stage of tempering. → Precipitation hardening is detected by the decrease in the background. - Abstract: Two steels containing 0.626 and 0.71 wt.% carbon have been studied to determine the effects of tempering on the microstructure and the internal friction. The steels were annealed at 1093 K, quenched into water and tempered for 60 min at 423 K, 573 K and 723 K. The increase of the tempering time diminishes the martensite tetragonality due to the redistribution of carbon atoms from octahedrical interstitial sites to dislocations. Internal friction spectrum is decomposed into five peaks and an exponential background, which are attributed to the carbide precipitation and the dislocation relaxation process. Simultaneous presence of peaks P1 and P2 indicates the interaction of dislocations with the segregated carbon and carbide precipitate.

  19. Measurement of effective renal plasma flow in congestive heart failure

    International Nuclear Information System (INIS)

    Tauxe, W.N.; Dubovsky, E.V.; Mantle, J.A.; Dustan, H.P.; Logic, J.R.

    1981-01-01

    In the management of patients with congestive heart failure (CHF), it is often desirable to have precise knowledge of overall renal function, including the effective renal plasma flow (ERPF). It has long been recognized that ERPF is diminished in CHF. Since glomerular filtration rate is often decreased to a much lesser extent, other noninvasive procedures such as the measurement of creatinine clearances may not be entirely suitable. ERPF determination by the single plasma sampling (SPS) method affords a rapid, simple, noninvasive, and economical technique that is quite accurate and reproducible. A SPS method has been well-tested in patients following renal transplantation plus a wide variety of nephrological disorders. We have been concerned whether the SPS method would be valid in volume expanded patients. In 28 determinations of ERPF in patients with CHF, and in five patients who did not have CHF, we have found the SPS estimation of ERPF to yield results that are not clinically significantly different from those obtained by the detailed compartmental analysis method. The volumes of 131 I-orthoiodohippurate (OIH) distribution were found to be somewhat higher in CHF than in controls, but fractional rate constants were proportionately lower so that intercompartmental flow rates and OIH concentrations were not different from controls. Therefore, the SPS estimation of ERPF is valid in patients with CHF and may be useful in monitoring the renal effects of various hemodynamic and pharmacological interventions. (orig.)

  20. Effect of flow parameters on flare stack generator noise

    International Nuclear Information System (INIS)

    Dinn, T.S.

    1998-01-01

    The SoundPLAN Computer Noise Model was used to determine the general effect of flare noise in a community adjacent to a petrochemical plant. Tests were conducted to determine the effect of process flow conditions and the pulsating flame on the flare stack generator noise from both a refinery flare and process flare. Flaring under normal plant operations, the flaring of fuel gas and the flaring of hydrogen were the three conditions that were tested. It was shown that the steam flow rate was the determining factor in the flare stack generated noise. Variations in the water seal level in the flare line surge tank increased or decreased the gas flowrate, which resulted in a pulsating flame. The period and amplitude of the pulsating noise from the flare stacks was determined by measuring several parameters. Flare stack noise oscillations were found to be greater for the process flare than for the refinery flare stack. It was suggested that minimizing the amount of steam fed to the flare and improving the burner design would minimize noise. 2 tabs., 6 figs