WorldWideScience

Sample records for core surface flow

  1. Fluid flow near the surface of earth's outer core

    Science.gov (United States)

    Bloxham, Jeremy; Jackson, Andrew

    1991-01-01

    This review examines the recent attempts at extracting information on the pattern of fluid flow near the surface of the outer core from the geomagnetic secular variation. Maps of the fluid flow at the core surface are important as they may provide some insight into the process of the geodynamo and may place useful constraints on geodynamo models. In contrast to the case of mantle convection, only very small lateral variations in core density are necessary to drive the flow; these density variations are, by several orders of magnitude, too small to be imaged seismically; therefore, the geomagnetic secular variation is utilized to infer the flow. As substantial differences exist between maps developed by different researchers, the possible underlying reasons for these differences are examined with particular attention given to the inherent problems of nonuniqueness.

  2. Core surface flow modelling from high-resolution secular variation

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils

    2006-01-01

    -flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....

  3. Decadal variability in core surface flows deduced from geomagnetic observatory monthly means

    DEFF Research Database (Denmark)

    Whaler, K. A.; Olsen, Nils; Finlay, Chris

    2016-01-01

    . On the annual to decadal timescale, the SV is generated primarily by advection in the fluid outer core. We demonstrate the utility of the revised monthly means by calculating models of the core surface advective flow between 1997 and 2013 directly from the SV data. One set of models assumes flow......Monthly means of the magnetic field measurements at ground observatories are a key data source for studying temporal changes of the core magnetic field. However, when they are calculated in the usual way, contributions of external (magnetospheric and ionospheric) origin may remain, which make them...... less favourable for studying the field generated by dynamo action in the core. We remove external field predictions, including a new way of characterising the magnetospheric ring current, from the data and then calculate revised monthly means using robust methods. The geomagnetic secular variation (SV...

  4. Nuclear reactor core flow baffling

    International Nuclear Information System (INIS)

    Berringer, R.T.

    1979-01-01

    A flow baffling arrangement is disclosed for the core of a nuclear reactor. A plurality of core formers are aligned with the grids of the core fuel assemblies such that the high pressure drop areas in the core are at the same elevations as the high pressure drop areas about the core periphery. The arrangement minimizes core bypass flow, maintains cooling of the structure surrounding the core, and allows the utilization of alternative beneficial components such as neutron reflectors positioned near the core

  5. Short-term variations in core surface flow resolved from an improved method of calculating observatory monthly means

    Science.gov (United States)

    Olsen, Nils; Whaler, Kathryn A.; Finlay, Christopher C.

    2014-05-01

    Monthly means of the magnetic field measurements taken by ground observatories are a useful data source for studying temporal changes of the core magnetic field and the underlying core flow. However, the usual way of calculating monthly means as the arithmetic mean of all days (geomagnetic quiet as well as disturbed) and all local times (day and night) may result in contributions from external (magnetospheric and ionospheric) origin in the (ordinary, omm) monthly means. Such contamination makes monthly means less favourable for core studies. We calculated revised monthly means (rmm), and their uncertainties, from observatory hourly means using robust means and after removal of external field predictions, using an improved method for characterising the magnetospheric ring current. The utility of the new method for calculating observatory monthly means is demonstrated by inverting their first differences for core surface advective flows. The flow is assumed steady over three consecutive months to ensure uniqueness; the effects of more rapid changes should be attenuated by the weakly conducting mantle. Observatory data are inverted directly for a regularised core flow, rather than deriving it from a secular variation spherical harmonic model. The main field is specified by the CHAOS-4 model. Data from up to 128 observatories between 1997 and 2013 were used to calculate 185 flow models from the omm and rmm, for each possible set of three consecutive months. The full 3x3 (non-diagonal) data covariance matrix was used, and two-norm (least squares) minimisation performed. We are able to fit the data to the target (weighted) misfit of 1, for both omm and rmm inversions, provided we incorporate the full data covariance matrix, and produce consistent, plausible flows. Fits are better for rmm flows. The flows exhibit noticeable changes over timescales of a few months. However, they follow rapid excursions in the omm that we suspect result from external field contamination

  6. Short-term variations in core surface flow resolved from an improved method of calculating observatory monthly means

    DEFF Research Database (Denmark)

    Olsen, Nils; Whaler, K. A.; Finlay, Chris

    2014-01-01

    Monthly means of the magnetic field measurements taken by ground observatories are a useful data source for studying temporal changes of the core magnetic field and the underlying core flow. However, the usual way of calculating monthly means as the arithmetic mean of all days (geomagnetic quiet...... as well as disturbed) and all local times (day and night) may result in contributions from external (magnetospheric and ionospheric) origin in the (ordinary, omm) monthly means. Such contamination makes monthly means less favourable for core studies. We calculated revised monthly means (rmm......), and their uncertainties, from observatory hourly means using robust means and after removal of external field predictions, using an improved method for characterising the magnetospheric ring current. The utility of the new method for calculating observatory monthly means is demonstrated by inverting their first...

  7. HANARO core channel flow-rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Tae; Im, Don Soon; Kim, Seon Duk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    HANARO core consists of 23 hexagonal flow tubes and 16 cylindrical flow tubes. To get the core flow distribution, we used 6 flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies). The differential pressures were measured and converted to flow-rates using the predetermined relationship between AP and flow-rate for each instrumented dummy fuel assemblies. The flow-rate for the cylindrical flow channels shows +-7% relative errors and that for the hexagonal flow channels shows +-3.5% relative errors. Generally the flow-rates of outer core channels show smaller values compared to those of inner core. The channels near to the core inlet pipe and outlet pipes also show somewhat lower flow-rates. For the lower flow channels, the thermal margin was checked by considering complete linear power histories. From the experimental results, the gap flow-rate was estimated to be 49.4 kg/s (cf. design flow of 50 kg/s). 15 tabs., 9 figs., 10 refs. (Author) .new.

  8. Rapidly changing flows in the Earth's core

    DEFF Research Database (Denmark)

    Olsen, Nils; Mandea, M.

    2008-01-01

    A large part of the Earth's magnetic field is generated by fluid motion in the molten outer core(1). As a result of continuous satellite measurements since 1999, the core magnetic field and its recent variations can now be described with a high resolution in space and time(2). These data have...... field occurring over only a few months, indicative of fluid flow at the top of the core, can in fact be resolved. Using nine years of magnetic field data obtained by satellites as well as Earth-based observatories, we determine the temporal changes in the core magnetic field and flow in the core. We...

  9. Reactor core flow rate control system

    International Nuclear Information System (INIS)

    Sakuma, Hitoshi; Tanikawa, Naoshi; Takahashi, Toshiyuki; Miyakawa, Tetsuya.

    1996-01-01

    When an internal pump is started by a variable frequency power source device, if magnetic fields of an AC generator are introduced after the rated speed is reached, neutron flux high scram occurs by abrupt increase of a reactor core flow rate. Then, in the present invention, magnetic fields for the AC generator are introduced at a speed previously set at which the fluctuation range of the reactor core flow rate (neutron flux) by the start up of the internal pump is within an allowable value. Since increase of the speed of the internal pump upon its start up is suppressed to determine the change of the reactor core flow rate within an allowable range, increase of neutron fluxes is suppressed to enable stable start up. Then, since transition boiling of fuels caused by abrupt decrease of the reactor core flow rate upon occurrence of abnormality in an external electric power system is prevented, and the magnetic fields for the AC generator are introduced in such a manner to put the speed increase fluctuation range of the internal pump upon start up within an allowable value, neutron flux high scram is not caused to enable stable start-up. (N.H.)

  10. CFD Analysis for Predicting Flow Resistance of the Cross Flow Gap in Prismatic VHTR Core

    International Nuclear Information System (INIS)

    Lee, Jeong Hun; Yoon, Su Jong; Park, Goon Cherl; Park, Jong Woon

    2011-01-01

    The core of Very High Temperature Reactor (VHTR) consists of assemblies of hexagonal graphite blocks and its height and across-flats width are 800 mm and 360 mm respectively. They are equipped with 108 coolant holes 16 mm in diameter. Up to ten fuel blocks arranged in vertical order form a fuel element column and the neutron flux varies over the cross section of the core. It makes different axial shrinkage of fuel element and this leads to make wedge-shaped gaps between the base and top surfaces of stacked blocks. The cross flow is defined as the core flow that passes through this cross gaps. The cross flow complicates the flow distribution of reactor core. Moreover, the cross flow could lead to uneven coolant distribution and consequently to superheating of individual fuel element zones with increased fission product release. Since the core cross flow has a negative impact on safety and efficiency of VHTR, core cross flow phenomena have to be investigated to improve the core thermal margin of VHTR. In particular, to predict amount of flow at the cross flow gap obtaining accurate flow loss coefficient is important. Nevertheless, there has not been much effort in domestic. The experiment of cross flow was carried out by H. G. Groehn in 1981 Germany. For the study of cross flow the applicability of CFD code should be validated. In this paper a commercial CFD code CFX-12 validation will be carried out with this cross flow experiment. Validated data can be used for validation of other thermal-hydraulic analysis codes

  11. Core flow inversion tested with numerical dynamo models

    Science.gov (United States)

    Rau, Steffen; Christensen, Ulrich; Jackson, Andrew; Wicht, Johannes

    2000-05-01

    We test inversion methods of geomagnetic secular variation data for the pattern of fluid flow near the surface of the core with synthetic data. These are taken from self-consistent 3-D models of convection-driven magnetohydrodynamic dynamos in rotating spherical shells, which generate dipole-dominated magnetic fields with an Earth-like morphology. We find that the frozen-flux approximation, which is fundamental to all inversion schemes, is satisfied to a fair degree in the models. In order to alleviate the non-uniqueness of the inversion, usually a priori conditions are imposed on the flow; for example, it is required to be purely toroidal or geostrophic. Either condition is nearly satisfied by our model flows near the outer surface. However, most of the surface velocity field lies in the nullspace of the inversion problem. Nonetheless, the a priori constraints reduce the nullspace, and by inverting the magnetic data with either one of them we recover a significant part of the flow. With the geostrophic condition the correlation coefficient between the inverted and the true velocity field can reach values of up to 0.65, depending on the choice of the damping parameter. The correlation is significant at the 95 per cent level for most spherical harmonic degrees up to l=26. However, it degrades substantially, even at long wavelengths, when we truncate the magnetic data sets to l currents, similar to those seen in core-flow models derived from geomagnetic data, occur in the equatorial region. However, the true flow does not contain this flow component. The results suggest that some meaningful information on the core-flow pattern can be retrieved from secular variation data, but also that the limited resolution of the magnetic core field could produce serious artefacts.

  12. Core flow control system for field applications; Sistema de controle de core-flow

    Energy Technology Data Exchange (ETDEWEB)

    Granzotto, Desiree G.; Adachi, Vanessa Y.; Bannwart, Antonio C.; Moura, Luiz F.M. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Sassim, Natache S.D.A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Centro de Estudo do Petroleo (CEPETRO); Carvalho, Carlos H.M. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The significant heavy oil reserves worldwide and the presently high crude oil prices make it essential the development of technologies for heavy oil production and transportation. Heavy oils, with their inherent features of high viscosity (100- 10,000 cP) and density (below 20 deg API) require specific techniques to make it viable their flow in pipes at high flow rates. One of the simplest methods, which do not require use of heat or diluents, is provided by oil-water annular flow (core-flow). Among the still unsolved issues regarding core-flow is the two-phase flow control in order to avoid abrupt increases in the pressure drop due to the possible occurrence of bad water-lubricated points, and thus obtain a safe operation of the line at the lowest possible water-oil ratio. This work presents results of core flow tests which allow designing a control system for the inlet pressure of the line, by actuating on the water flow rate at a fixed oil flow rate. With the circuit model and the specified controller, simulations can be done to assess its performance. The experiments were run at core-flow circuit of LABPETRO-UNICAMP. (author)

  13. Surface obstacles in pulsatile flow

    Science.gov (United States)

    Carr, Ian A.; Plesniak, Michael W.

    2017-11-01

    Flows past obstacles mounted on flat surfaces have been widely studied due to their ubiquity in nature and engineering. For nearly all of these studies, the freestream flow over the obstacle was steady, i.e., constant velocity, unidirectional flow. Unsteady, pulsatile flows occur frequently in biology, geophysics, biomedical engineering, etc. Our study is aimed at extending the comprehensive knowledge base that exists for steady flows to considerably more complex pulsatile flows. Characterizing the vortex and wake dynamics of flows around surface obstacles embedded in pulsatile flows can provide insights into the underlying physics in all wake and junction flows. In this study, we experimentally investigate the wake of two canonical obstacles: a cube and a circular cylinder with an aspect ratio of unity. Our previous studies of a surface-mounted hemisphere in pulsatile flow are used as a baseline for these two new, more complex geometries. Phase-averaged PIV and hot-wire anemometry are used to characterize the dynamics of coherent structures in the wake and at the windward junction of the obstacles. Complex physics occur during the deceleration phase of the pulsatile inflow. We propose a framework for understanding these physics based on self-induced vortex propagation, similar to the phenomena exhibited by vortex rings.

  14. Computer-Aided Test Flow in Core-Based Design

    OpenAIRE

    Zivkovic, V.; Tangelder, R.J.W.T.; Kerkhoff, Hans G.

    2000-01-01

    This paper copes with the test-pattern generation and fault coverage determination in the core based design. The basic core-test strategy that one has to apply in the core-based design is stated in this work. A Computer-Aided Test (CAT) flow is proposed resulting in accurate fault coverage of embedded cores. The CAT now is applied to a few cores within the Philips Core Test Pilot IC project

  15. Flow over riblet curved surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J B R; Freire, A P Silva, E-mail: atila@mecanica.ufrj.br [Mechanical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), C.P. 68503, 21.941-972, Rio de Janeiro, RJ (Brazil)

    2011-12-22

    The present work studies the mechanics of turbulent drag reduction over curved surfaces by riblets. The effects of surface modification on flow separation over steep and smooth curved surfaces are investigated. Four types of two-dimensional surfaces are studied based on the morphometric parameters that describe the body of a blue whale. Local measurements of mean velocity and turbulence profiles are obtained through laser Doppler anemometry (LDA) and particle image velocimetry (PIV).

  16. Core-annular flow through a horizontal pipe : Hydrodynamic counterbalancing of buoyancy force on core

    NARCIS (Netherlands)

    Ooms, G.; Vuik, C.; Poesio, P.

    2007-01-01

    A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question of how the buoyancy force on the core, caused by a density difference

  17. Numerical simulation on coolant flow and heat transfer in core

    International Nuclear Information System (INIS)

    Yao Zhaohui; Wang Xuefang; Shen Mengyu

    1997-01-01

    To simulate the coolant flow and the heat transfer characteristics of a core, a computer code, THAPMA (Thermal Hydraulic Analysis Porous Medium Analysis) has been developed. In THAPMA code, conservation equations are based on a porous-medium formulation, which uses four parameters, i.e, volume porosity, directional surface porosity, distributed resistance, and distributed heat source (sink), to model the effects of fuel rods and other internal solid structures on flow and heat transfer. Because the scheme and the solution are very important in accuracy and speed of calculation, a new difference scheme (WSUC) has been used in the energy equation, and a modified PISO solution method have been employed to simulate the steady/transient states. The code has been proved reliable and can effectively solve the transient state problem by several numerical tests. According to the design of Qinshan NPP-II, the flow and heat transfer phenomena in reactor core have been numerically simulated. The distributions of the velocity and the temperature can provide a theoretical basis for core design and safety analysis

  18. 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.

  19. Surface flow measurements from drones

    Science.gov (United States)

    Tauro, Flavia; Porfiri, Maurizio; Grimaldi, Salvatore

    2016-09-01

    Drones are transforming the way we sense and interact with the environment. However, despite their increased capabilities, the use of drones in geophysical sciences usually focuses on image acquisition for generating high-resolution maps. Motivated by the increasing demand for innovative and high performance geophysical observational methodologies, we posit the integration of drone technology and optical sensing toward a quantitative characterization of surface flow phenomena. We demonstrate that a recreational drone can be used to yield accurate surface flow maps of sub-meter water bodies. Specifically, drone's vibrations do not hinder surface flow observations, and velocity measurements are in agreement with traditional techniques. This first instance of quantitative water flow sensing from a flying drone paves the way to novel observations of the environment.

  20. Paleomagnetic correlation of surface and subsurface basaltic lava flows and flow groups in the southern part of the Idaho National Laboratory, Idaho, with paleomagnetic data tables for drill cores

    Science.gov (United States)

    Champion, Duane E.; Hodges, Mary K.V.; Davis, Linda C.; Lanphere, Marvin A.

    2011-01-01

    Paleomagnetic inclination and polarity studies have been conducted on thousands of subcore samples from 51 coreholes located at and near the Idaho National Laboratory. These studies are used to paleomagnetically characterize and correlate successive stratigraphic intervals in each corehole to similar depth intervals in adjacent coreholes. Paleomagnetic results from 83 surface paleomagnetic sites, within and near the INL, are used to correlate these buried lava flow groups to basaltic shield volcanoes still exposed on the surface of the eastern Snake River Plain. Sample handling and demagnetization protocols are described as well as the paleomagnetic data averaging process. Paleomagnetic inclination comparisons between coreholes located only kilometers apart show comparable stratigraphic successions of mean inclination values over tens of meters of depth. At greater distance between coreholes, comparable correlation of mean inclination values is less consistent because flow groups may be missing or additional flow groups may be present and found at different depth intervals. Two shallow intersecting cross-sections, A-A- and B-B- (oriented southwest-northeast and northwest-southeast, respectively), drawn through southwest Idaho National Laboratory coreholes show the corehole to corehole or surface to corehole correlations derived from the paleomagnetic inclination data. From stratigraphic top to bottom, key results included the (1) Quaking Aspen Butte flow group, which erupted from Quaking Aspen Butte southwest of the Idaho National Laboratory, flowed northeast, and has been found in the subsurface in corehole USGS 132; (2) Vent 5206 flow group, which erupted near the southwestern border of the Idaho National Laboratory, flowed north and east, and has been found in the subsurface in coreholes USGS 132, USGS 129, USGS 131, USGS 127, USGS 130, USGS 128, and STF-AQ-01; and (3) Mid Butte flow group, which erupted north of U.S. Highway 20, flowed northwest, and has been

  1. Flow distribution in ET-RR-1 core

    International Nuclear Information System (INIS)

    Khattab, M.; Mina, A.R.

    1989-01-01

    In nuclear reactors the flow may be arranged through individual bundles by orifices to achieve better thermal performance. A model based on constant pressure drop across different core regions is developed to determine the flow distribution in reactor core. The friction and grids in the bundles as well as the orifices diameters have an influence on modifying the flow distribution. The application of the proposed model on ET-RR-1 gives reasonable prediction of flow distribution

  2. Computer-Aided Test Flow in Core-Based Design

    NARCIS (Netherlands)

    Zivkovic, V.; Tangelder, R.J.W.T.; Kerkhoff, Hans G.

    2000-01-01

    This paper copes with the efficient test-pattern generation in a core-based design. A consistent Computer-Aided Test (CAT) flow is proposed based on the required core-test strategy. It generates a test-pattern set for the embedded cores with high fault coverage and low DfT area overhead. The CAT

  3. Computer-Aided Test Flow in Core-Based Design

    NARCIS (Netherlands)

    Zivkovic, V.; Tangelder, R.J.W.T.; Kerkhoff, Hans G.

    2000-01-01

    This paper copes with the test-pattern generation and fault coverage determination in the core based design. The basic core-test strategy that one has to apply in the core-based design is stated in this work. A Computer-Aided Test (CAT) flow is proposed resulting in accurate fault coverage of

  4. Core Flow Distribution from Coupled Supercritical Water Reactor Analysis

    Directory of Open Access Journals (Sweden)

    Po Hu

    2014-01-01

    Full Text Available This paper introduces an extended code package PARCS/RELAP5 to analyze steady state of SCWR US reference design. An 8 × 8 quarter core model in PARCS and a reactor core model in RELAP5 are used to study the core flow distribution under various steady state conditions. The possibility of moderator flow reversal is found in some hot moderator channels. Different moderator flow orifice strategies, both uniform across the core and nonuniform based on the power distribution, are explored with the goal of preventing the reversal.

  5. Alteration of helical vortex core without change in flow topology

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Okulov, Valery; Hansen, Martin Otto Laver

    2011-01-01

    topology. The helical symmetry as such is preserved, although the characteristic parameters of helical symmetry of the vortex core transfer from a smooth linear variation to a different trend under the influence of a non-uniform pressure gradient, causing an increase in helical pitch without changing its......The abrupt expansion of the slender vortex core with changes in flow topology is commonly known as vortex breakdown. We present new experimental observations of an alteration of the helical vortex core in wall bounded turbulent flow with abrupt growth in core size, but without change in flow...

  6. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Coles, D.G.; Bazan, F.

    1982-01-01

    Both crushed (150- to 300- μm) and cored (1,8- mm-diam) samples of SYNROC have been leached with single-pass continuous-flow leaching equipment. Crushed samples of cesium-hollandite were also leached in a similar experiment. Temperatures used were 25 0 and 75 0 C and leachates were 0.03 N NaHCO 3 and distilled water. Leaching rates from SYNROC-C were ranked cesium > strontium greater than or equal to calcium > barium > zirconium. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and Pacific Northwest Laboratory 76-68 glass beads. This comparison depends on how the surface areas are determined for each sample. Based on geometric surface areas for SYNROC cores and glass beads, cesium leach rates from SYNROC compare well with both sodium and neptunium leached from the glass. The other elements leached from SYNROC are lower than sodium and neptunium leached from glass. They also vary for each element, while glass shows nearly the same leach rate for both sodium and neptunium

  7. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Coles, D.G.; Bazan, F.

    1981-01-01

    Both crushed (150 to 300 μm) and cored (1.8 mm diameter) samples of SYNROC have been leached with the single-pass continuous-flow leaching equipment. Crushed samples of Cs-hollandite were also leached in a similar experiment. Temperatures used were 25 and 75 0 C and leachates were 0.03 N NaHCO 3 and distilled water. Leaching rates from SYNROC C were ranked Cs > Sr greater than or equal to Ca > Ba > Zr. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and PNL 76-68 glass beads. This comparison depends on how the surface areas are determined for each sample. Based on geometric surface areas for SYNROC cores and glass beads Cs leach rates from SYNROC compare well with both Na and Np leached from the glass. The other elements leached from SYNROC are lower than Na and Np leached from glass. They also vary for each element while glass shows nearly the same leach rate for both Na and Np

  8. In-core flow rate distribution measurement test of the JOYO irradiation core

    International Nuclear Information System (INIS)

    Suzuki, Toshihiro; Isozaki, Kazunori; Suzuki, Soju

    1996-01-01

    A flow rate distribution measurement test was carried out for the JOYO irradiation core (the MK-II core) after the 29th duty cycle operation. The main object of the test is to confirm the proper flow rate distribution at the final phase of the MK-II core. The each flow rate at the outlet of subassemblies was measured by the permanent magnetic flowmeter inserted avail of fuel exchange hole in the rotating plug. This is third test in the MK-II core, after 10 years absence from the final test (1985). Total of 550 subassemblies were exchanged and accumulated reactor operation time reached up to 38,000 hours from the previous test. As a conclusion, it confirmed that the flow rate distribution has been kept suitable in the final phase of the MK-II core. (author)

  9. Singularities in Free Surface Flows

    Science.gov (United States)

    Thete, Sumeet Suresh

    Free surface flows where the shape of the interface separating two or more phases or liquids are unknown apriori, are commonplace in industrial applications and nature. Distribution of drop sizes, coalescence rate of drops, and the behavior of thin liquid films are crucial to understanding and enhancing industrial practices such as ink-jet printing, spraying, separations of chemicals, and coating flows. When a contiguous mass of liquid such as a drop, filament or a film undergoes breakup to give rise to multiple masses, the topological transition is accompanied with a finite-time singularity . Such singularity also arises when two or more masses of liquid merge into each other or coalesce. Thus the dynamics close to singularity determines the fate of about-to-form drops or films and applications they are involved in, and therefore needs to be analyzed precisely. The primary goal of this thesis is to resolve and analyze the dynamics close to singularity when free surface flows experience a topological transition, using a combination of theory, experiments, and numerical simulations. The first problem under consideration focuses on the dynamics following flow shut-off in bottle filling applications that are relevant to pharmaceutical and consumer products industry, using numerical techniques based on Galerkin Finite Element Methods (GFEM). The second problem addresses the dual flow behavior of aqueous foams that are observed in oil and gas fields and estimates the relevant parameters that describe such flows through a series of experiments. The third problem aims at understanding the drop formation of Newtonian and Carreau fluids, computationally using GFEM. The drops are formed as a result of imposed flow rates or expanding bubbles similar to those of piezo actuated and thermal ink-jet nozzles. The focus of fourth problem is on the evolution of thinning threads of Newtonian fluids and suspensions towards singularity, using computations based on GFEM and experimental

  10. The influence of core bypass flow during SBLOCA

    International Nuclear Information System (INIS)

    Maselj, A.; Jurkovic, M.

    1996-01-01

    Many parameters affect the behaviour of a NPP during a Small Break Loss of Coolant Accident (SBLOCA). The bypass flow between the core side and the downcomer is one of them. Different PWRs have different values of core bypass flow. In spite of the complexity of the real situation in the primary system during SBLOCA, some fundamental details of the phenomena can be explained with simplified mathematical models, which relate on basic parameters of the primary coolant. These models define the conditions for loop seal clearance and final results are confirmed with measured values. The analysis presented in the paper refers to Bethsy Test 9.1.b SB LOCA scenario, with variation of core bypass flow. Basic RELAP5 input model calculation results show very good agreement with the experimental data. The core liquid level depression before loop seal clearance is lower in case of smaller core bypass flow. This affects the fuel clad temperature because of different heat transfer mechanisms. Time of loop seal clearance is delayed with larger core bypass flow and consequently lower differential pressure between downcomer and core. (author)

  11. Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth's core surface

    DEFF Research Database (Denmark)

    Gillet, N.; Jault, D.; Finlay, Chris

    2015-01-01

    between the magnetic field and subdecadal nonzonal motions within the fluid outer core. Both the zonal and the more energetic nonzonal interannual motions were particularly intense close to the equator (below 10∘ latitude) between 1995 and 2010. We revise down the amplitude of the decade fluctuations......We report a calculation of time-dependent quasi-geostrophic core flows for 1940–2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely, the model errors arising from interactions between unresolved core surface motions and magnetic fields....... Temporal correlations of these uncertainties are accounted for. The covariance matrix for the flow coefficients is also obtained recursively from the dispersion of an ensemble of solutions. Maps of the flow at the core surface show, upon a planetary-scale gyre, time-dependent large-scale eddies...

  12. ac power control in the Core Flow Test Loop

    International Nuclear Information System (INIS)

    McDonald, D.W.

    1980-01-01

    This work represents a status report on a development effort to design an ac power controller for the Core Flow Test Loop. The Core Flow Test Loop will be an engineering test facility which will simulate the thermal environment of a gas-cooled fast-breeder reactor. The problems and limitations of using sinusoidal ac power to simulate the power generated within a nuclear reactor are addressed. The transformer-thyristor configuration chosen for the Core Flow Test Loop power supply is presented. The initial considerations, design, and analysis of a closed-loop controller prototype are detailed. The design is then analyzed for improved performance possibilities and failure modes are investigated at length. A summary of the work completed to date and a proposed outline for continued development completes the report

  13. Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals

    Directory of Open Access Journals (Sweden)

    Noor A. Nama

    2010-01-01

    Full Text Available Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001-(1×1 surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

  14. Forces on zonal flows in tokamak core turbulence

    International Nuclear Information System (INIS)

    Hallatschek, K.; Itoh, K.

    2005-01-01

    The saturation of stationary zonal flows (ZF) in the core of a tokamak has been analyzed in numerical fluid turbulence computer studies. The model was chosen to properly represent the kinetic global plasma flows, i.e., undamped stationary toroidal or poloidal flows and Landau damped geodesic acoustic modes. Reasonable agreement with kinetic simulations in terms of magnitude of transport and occurrence of the Dimits shift was verified. Contrary to common perception, in the final saturated state of turbulence and ZFs, the customary perpendicular Reynolds stress continues to drive the ZFs. The force balance is established by the essentially quasilinear parallel Reynolds stress acting on the parallel return flows required by incompressibility. (author)

  15. Temporal Change of Seismic Earth's Inner Core Phases: Inner Core Differential Rotation Or Temporal Change of Inner Core Surface?

    Science.gov (United States)

    Yao, J.; Tian, D.; Sun, L.; Wen, L.

    2017-12-01

    Since Song and Richards [1996] first reported seismic evidence for temporal change of PKIKP wave (a compressional wave refracted in the inner core) and proposed inner core differential rotation as its explanation, it has generated enormous interests in the scientific community and the public, and has motivated many studies on the implications of the inner core differential rotation. However, since Wen [2006] reported seismic evidence for temporal change of PKiKP wave (a compressional wave reflected from the inner core boundary) that requires temporal change of inner core surface, both interpretations for the temporal change of inner core phases have existed, i.e., inner core rotation and temporal change of inner core surface. In this study, we discuss the issue of the interpretation of the observed temporal changes of those inner core phases and conclude that inner core differential rotation is not only not required but also in contradiction with three lines of seismic evidence from global repeating earthquakes. Firstly, inner core differential rotation provides an implausible explanation for a disappearing inner core scatterer between a doublet in South Sandwich Islands (SSI), which is located to be beneath northern Brazil based on PKIKP and PKiKP coda waves of the earlier event of the doublet. Secondly, temporal change of PKIKP and its coda waves among a cluster in SSI is inconsistent with the interpretation of inner core differential rotation, with one set of the data requiring inner core rotation and the other requiring non-rotation. Thirdly, it's not reasonable to invoke inner core differential rotation to explain travel time change of PKiKP waves in a very small time scale (several months), which is observed for repeating earthquakes in Middle America subduction zone. On the other hand, temporal change of inner core surface could provide a consistent explanation for all the observed temporal changes of PKIKP and PKiKP and their coda waves. We conclude that

  16. Reverse Flow Engine Core Having a Ducted Fan with Integrated Secondary Flow Blades

    Science.gov (United States)

    Kisska, Michael K. (Inventor); Princen, Norman H. (Inventor); Kuehn, Mark S. (Inventor); Cosentino, Gary B. (Inventor)

    2014-01-01

    Secondary air flow is provided for a ducted fan having a reverse flow turbine engine core driving a fan blisk. The fan blisk incorporates a set of thrust fan blades extending from an outer hub and a set of integral secondary flow blades extending intermediate an inner hub and the outer hub. A nacelle provides an outer flow duct for the thrust fan blades and a secondary flow duct carries flow from the integral secondary flow blades as cooling air for components of the reverse flow turbine engine.

  17. Neutronics of a mixed-flow gas-core reactor

    International Nuclear Information System (INIS)

    Soran, P.D.; Hansen, G.E.

    1977-11-01

    The study was made to investigate the neutronic feasibility of a mixed-flow gas-core reactor. Three reactor concepts were studied: four- and seven-cell radial reactors and a seven-cell scallop reactor. The reactors were fueled with UF 6 (either U-233 or U-235) and various parameters were varied. A four-cell reactor is not practical nor is the U-235 fueled seven-cell radial reactor; however, the 7-cell U-233 radial and scallop reactors can satisfy all design criteria. The mixed flow gas core reactor is a very attractive reactor concept and warrants further investigation

  18. Burnout and distribution of liquid between the flow core and wall films in narrow slot channels

    Science.gov (United States)

    Boltenko, E. A.; Shpakovskii, A. A.

    2010-03-01

    Previous works on studying distribution of liquid between the flow core and wall films in narrow slot channels are briefly reviewed. Interrelation between mass transfer processes and burnout is shown. A procedure for calculating burnout on convex and concave heat-transfer surfaces in narrow slot channels is presented.

  19. Numerical and experimental investigation on labyrinth seal mechanism for bypass flow reduction in prismatic VHTR core

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Su-Jong, E-mail: paper80@snu.ac.r [Department of Nuclear Engineering, Seoul National University, San 56-1, Daehak-Dong, Kwanak-Gu, Seoul 151-742 (Korea, Republic of); Lee, Jeong-Hun [Department of Nuclear Engineering, Seoul National University, San 56-1, Daehak-Dong, Kwanak-Gu, Seoul 151-742 (Korea, Republic of); Lee, Sang-Moon [Department of Mechanical Engineering, Inha University, 253 Yonghyun-Dong, Nam-Gu, Incheon 402-751 (Korea, Republic of); Tak, Nam-il; Kim, Min-Hwan [Korea Atomic Energy Research Institute, 150-1 Deokjin-Dong, 1045 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea, Republic of); Kim, Kwang-Yong [Department of Mechanical Engineering, Inha University, 253 Yonghyun-Dong, Nam-Gu, Incheon 402-751 (Korea, Republic of); Park, Goon-Cherl [Department of Nuclear Engineering, Seoul National University, San 56-1, Daehak-Dong, Kwanak-Gu, Seoul 151-742 (Korea, Republic of)

    2013-09-15

    Highlights: • Bypass flow reduction method was developed by applying labyrinth seal mechanism. • Grooves on side walls of replaceable reflector block were made. • Design of the grooved wall of the reflector block was optimized by the RSA method. • The flow resistance of the bypass gap rose from 18.04 to 26.24 by the optimization. • The bypass ratios at the inlet and outlet were reduced by 36.19% and 14.66%, respectively. -- Abstract: Core bypass flow in block type very high temperature reactor (VHTR) occurs due to the inevitable gaps between the hexagonal core blocks for the block installation and refueling. Since the core bypass flow affects the reactor safety and efficiency, it should be minimized to enhance the core thermal margin. In this regard, the core bypass flow reduction method applying the labyrinth seal mechanism was developed and optimized by using the single-objective shape optimization method. Response surface approximation (RSA) method was adopted as the optimization method. Side wall of the replaceable reflector block was redesigned and response surface approximate model was adopted to optimize the shape of the reflector wall. Computational fluid dynamics (CFD) analyses were carried out not only to assess the limitation of existing method of bypass flow reduction, but also to optimize the design of a newly developed reduction method. The experiment with Seoul National University (SNU) multi-block experimental facility was performed to demonstrate the performance of the reduction method. It was found that the effect of the existing bypass flow reduction method by sealing the bypass gap exit was restricted nearby the lower region of the core. However, the flow resistance factor of the bypass gap increased from 18.04 to 26.24 by the optimized reduction method. The results of the performance test showed that the bypass flow distribution was reduced throughout the entire core regions. The bypass flow ratios at the inlet and the outlet were

  20. Simulation of gas compressible flow by free surface water flow

    International Nuclear Information System (INIS)

    Altafini, C.R.; Silva Ferreira, R.T. da

    1981-01-01

    The analogy between the water flow with a free surface and the compressible fluid flow, commonly called hydraulic analogy, is analyzed and its limitations are identified. The water table is the equipment used for this simulation, which allows the quatitative analysis of subsonic and supersonic flow with a low cost apparatus. The hydraulic analogy is applied to subsonic flow around circular cylinders and supersonic flow around cones. The results are compared with available theoretical and experimental data and a good agreement is achieved. (Author) [pt

  1. Accidents and transients analyses of a super fast reactor with single flow pass core

    International Nuclear Information System (INIS)

    Sutanto,; Oka, Yoshiaki

    2014-01-01

    Highlights: • Safety analysis of a Super FR with single flow pass core is conducted. • Loss of feed water flow leads to a direct effect on the loss of fuel channel flow. • The core pressure is sensitive to LOCA accidents due to the direct effect. • Small LOCA introduces a critical break. • The safety criteria for all selected events are satisfied. - Abstract: The supercritical water cooled fast reactor with single flow pass core has been designed to simplify refueling and the structures of upper and lower mixing plenums. To evaluate the safety performance, safety analysis has been conducted with regard to LOCA and non-LOCA accidents including transient events. Safety analysis results show that the safety criteria are satisfied for all selected events. The total loss of feed water flow is the most important accident which the maximum cladding surface temperature (MCST) is high due to a direct effect of the accident on the total loss of flow in all fuel assemblies. However, actuation of the ADS can mitigate the accident. Small LOCA also introduces a critical break at 7.8% break which results high MCST at BOC because the scram and ADS are not actuated. Early ADS actuation is effective to mitigate the accident. In large LOCA, 100% break LOCA results a high MCST of flooding phase at BOC due to high power peaking at the bottom part. Use of high injection flow rate by 2 LPCI units is effective to decrease the MCST

  2. Instability of flow of liquid film over a heated surface

    International Nuclear Information System (INIS)

    Sha, W.T.

    1994-01-01

    Fundamental concepts and basic equations of a flowing thin liquid film cooling a heated surfaced by its vaporization and the effect of dry patches were treated. Stable film flow prior to the appearance of dry patches on the heated surface is maintained by a balance of various forces due to surface tension, shear stress, heat and mass transfer, and gravity. Film splitting at a critical film thickness produces dry patches due to perturbation by waves on a perfect surface, and often by surface imperfection and uneven heating. This work is primarily motivated by the design of next-generation nuclear reactors, which employ many novel passive heat-removal systems via natural circulation. These systems are design to prevent damage to the reactor core and containment without action by the reactor operators during or after a design basis accident such as a loss of coolant accident (LOCA) or a main steam-line break (MSLB) accident

  3. Influence of core sand properties on flow dynamics of core shooting process based on experiment and multiphase simulation

    Directory of Open Access Journals (Sweden)

    Chang-jiang Ni

    2017-03-01

    Full Text Available The influence of core sand properties on flow dynamics was investigated synchronously with various core sands, transparent core-box and high-speed camera. To confirm whether the core shooting process has significant turbulence, the flow pattern of sand particles in the shooting head and core box was reproduced with colored core sands. By incorporating the kinetic theory of granular flow (KTGF, kinetic-frictional constitutive correlation and turbulence model, a two-fluid model (TFM was established to study the flow dynamics of the core shooting process. Two-fluid model (TFM simulations were then performed and a areasonable agreement was achieved between the simulation and experimental results. Based on the experimental and simulation results, the effects of turbulence, sand density, sand diameter and binder ratio were analyzed in terms of filling process, sand volume fraction (αs and sand velocity (Vs.

  4. Covalent Attachment of Bent-Core Mesogens to Silicon Surfaces

    NARCIS (Netherlands)

    Scheres, L.; Achten, R.; Giesbers, M.; Smet, de L.; Arafat, A.; Sudhölter, E.J.R.; Marcelis, A.T.M.; Zuilhof, H.

    2009-01-01

    Two vinyl-terminated bent core-shaped liquid crystalline molecules that exhibit thermotropic antiferroelectric SmCPA phases have been covalently attached onto a hydrogen-terminated silicon(111) surface. The surface attachment was achieved via a mild procedure from a mesitylene solution, using

  5. Study on core flow distribution of the reference core design Mark-III of experimental multi-purpose VHTR

    International Nuclear Information System (INIS)

    Satoh, Sadao; Arai, Taketoshi; Miyamoto, Yoshiaki; Hirano, Mitsumasa

    1977-01-01

    Concerning the coolant flow distribution between fuel channels and other flow paths in the core, designated as Reference Core Mark-III of the Multi-purpose Experimental Very High Temperature Reactor, thermal analysis has been made of the control rods and other steel structures around the core to find the coolant flow rates (bypass flow) necessary to cool them to their safe operating temperatures. Calculations showed that adequate cooling could be achieved in the Mark-III Core by the bypass flow of 8% of the total reactor coolant flow, 4% each for the control-rod channels and for other structures. The thermal and coolant flow design bases, including the assumption of a 10% bypass flow, were thus confirmed to first approximation. (auth.)

  6. Surface core-level shifts for simple metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1994-01-01

    screening, whereby a SCLS becomes equivalent to the surface segregation energy of a core-ionized atom, a quantity we obtain by separate bulk and surface impurity calculations. The results are in good agreement with experiment in most of those cases where the data originates from single-crystal measurements....... We discuss the surface shifts of the electrostatic potentials and the band centers in order to trace the microscopic origin of the SCLS in the simple metals and find that the anomalous subsurface core-level shifts in beryllium are caused by charge dipoles, which persist several layers into the bulk...

  7. Characterization of interfacial waves in horizontal core-annular flow

    Science.gov (United States)

    Tripathi, Sumit; Bhattacharya, Amitabh; Singh, Ramesh; Tabor, Rico F.

    2016-11-01

    In this work, we characterize interfacial waves in horizontal core annular flow (CAF) of fuel-oil and water. Experimental studies on CAF were performed in an acrylic pipe of 15.5mm internal diameter, and the time evolution of the oil-water interface shape was recorded with a high speed camera for a range of different flow-rates of oil (Qo) and water (Qw). The power spectrum of the interface shape shows a range of notable features. First, there is negligible energy in wavenumbers larger than 2 π / a , where a is the thickness of the annulus. Second, for high Qo /Qw , there is no single dominant wavelength, as the flow in the confined annulus does not allow formation of a preferred mode. Third, for lower Qo /Qw , a dominant mode arises at a wavenumber of 2 π / a . We also observe that the power spectrum of the interface shape depends weakly on Qw, and strongly on Qo, perhaps because the net shear rate in the annulus appears to depend weakly on Qw as well. We also attempt to build a general empirical model for CAF by relating the interfacial stress (calculated via the mean pressure gradient) to the flow rate in the annulus, the annular thickness and the core velocity. Authors are thankful to Orica Mining Services (Australia) for the financial support.

  8. Device for measuring flow rate in a nuclear reactor core

    International Nuclear Information System (INIS)

    Hamano, Jiro.

    1980-01-01

    Purpose: To always calculate core flow rate automatically and accurately in BWR type nuclear power plants. Constitution: Jet pumps are provided to the recycling pump and to the inside of the pressure vessel of a nuclear reactor. The jet pumps comprise a plurality of calibrated jet pumps for forcively convecting the coolants and a plurality of not calibrated jet pumps in order to cool the heat generated in the reactor core. The difference in the pressures between the upper and the lower portions in both of the jet pumps is measured by difference pressure transducers. Further, a thermo-sensitive element is provided to measure the temperature of recycling water at the inlet of the recycling pump. The output signal from the difference pressure transducer is inputted to a process computer, calculated periodically based on predetermined calculation equations, compensated for the temperature by a recycling water temperature signal and outputted as a core flow rate signal to a recoder. The signal is also used for the power distribution calculation in the process computer and the minimum limit power ratio as the thermal limit value for the fuels is outputted. (Furukawa, Y.)

  9. Analytical study on coolant temperature of several leak flows in the experimental VHTr core

    International Nuclear Information System (INIS)

    Fumizawa, Motoh; Arai, Taketoshi; Miyamoto, Yoshiaki

    1982-08-01

    This report describes heat transfer analysis of several leak flows which bypass main coolant flow path in the experimental VHTR core. The analysis contains the leak flow at permanent reflectors, replaceable reflectors and gaps between fuel columns. The summary of the results are as follows: (1) the temperature of the leak flow gas increases up to the surface temperature of permanent reflectors, (2) the gas temperature at replaceable reflectors increases at least 40 0 C in case of the worst analytical condition, (3) the gas temperature increases remarkably with decreasing equivalent diameter which is changed by the angle of bevel edge of the reflector, (4) while the gas temperature is low at the upper part of the fuel element, the temperature increases rapidly when it flow down along the gap of the fuel columns. (author)

  10. Influence of core flows on the decade variations of the polar motion

    Science.gov (United States)

    Hulot, G.; Le Huy, M.; Le Mouël, J.-L.

    We address the possibility for the core flows that generate the geomagnetic field to contribute significantly to the decade variations of the mean pole position (generally called the Markowitz wobble). This assumption is made plausible by the observation that the flow at the surface of the core-estimated from the geomagnetic secular variation models-experiences important changes on this time scale. We discard the viscous and electromagnetic core-mantle couplings and consider only the pressure torque pf resulting from the fluid flow overpressure acting on the non-spherical core-mantle boundary (CMB) at the bottom of the mantle, and the gravity torque gf due to the density heterogeneity driving the core flow. We show that forces within the core balance each other on the time scale considered and, using global integrals over the core, the mantle and the whole Earth, we write Euler's equation for the mantle in terms of two more useful torques Pgeo and . The "geostrophic torque", γ Pgeo incorporates γpf and part of γgf, while γ is another fraction of γgf. We recall how the geostrophic pressure pgeo, and thus γPgeo for a given topography, can be derived from the flow at the CMB and compute the motion of the mean pole from 1900 to 1990, assuming in a first approach that the unknown γ can be neglected. The amplitude of the computed pole motion is three to ten times less than the observed one and out of the phase with it. In order to estimate the possible contribution of γ we then use a second approach and consider the case in which the reference state for the Earth is assumed to be the classical axisymmetric ellipsoidal figure with an almost constant ellipticity within the core. We show that (γPgeo + γ) is then equal to a pseudo-electromagnetic torque γL3, the torque exerted on the core by the component of the Lorentz force along the axis of rotation (this torque exists even though the mantle is assumed insulating). This proves that, at least in this case and

  11. Cores, Joins and the Fano-Flow Conjectures

    Directory of Open Access Journals (Sweden)

    Jin Ligang

    2018-02-01

    Full Text Available The Fan-Raspaud Conjecture states that every bridgeless cubic graph has three 1-factors with empty intersection. A weaker one than this conjecture is that every bridgeless cubic graph has two 1-factors and one join with empty intersection. Both of these two conjectures can be related to conjectures on Fano-flows. In this paper, we show that these two conjectures are equivalent to some statements on cores and weak cores of a bridgeless cubic graph. In particular, we prove that the Fan-Raspaud Conjecture is equivalent to a conjecture proposed in [E. Steffen, 1-factor and cycle covers of cubic graphs, J. Graph Theory 78 (2015 195–206]. Furthermore, we disprove a conjecture proposed in [G. Mazzuoccolo, New conjectures on perfect matchings in cubic graphs, Electron. Notes Discrete Math. 40 (2013 235–238] and we propose a new version of it under a stronger connectivity assumption. The weak oddness of a cubic graph G is the minimum number of odd components (i.e., with an odd number of vertices in the complement of a join of G. We obtain an upper bound of weak oddness in terms of weak cores, and thus an upper bound of oddness in terms of cores as a by-product.

  12. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Coles, D.G.; Bazan, F.

    1980-01-01

    Both crushed (150 to 300 μm) and cored 1.8 mm diameter) samples of SYNROC have been leached with the single-pass continuous-flow leaching equipment. Crushed samples of Cs-hollandite were also leached in a similar experiment. Temperatures used were 25 0 C and 75 0 C and leachates were 0.03 N NaHCO 3 and distilled water. Leaching rates from SYNROC C were ranked Cs > Sr greater than or equal to Ca > Ba > Zr. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and PNL 76-68 glass beads. Problems encountered when comparing the leaching rates of different waste forms are discussed

  13. Radionuclide transfer onto ground surface in surface water flow, 1

    International Nuclear Information System (INIS)

    Mukai, Masayuki; Takebe, Shinichi; Komiya, Tomokazu; Kamiyama, Hideo

    1991-07-01

    Radionuclides migration in ground surface water flow is considered to be one of the important path way in the scenario for environmental migration of radionuclides leaked from low level radioactive waste repository. Simulating the slightly sloped surface on which contaminated solution is flowing downward, testing for radionuclide migration on ground surface had been started. As it's first step, an experiment was carried out under the condition of restricted infiltration in order to elucidate the adsorption behavior of radionuclides onto the loamy soil surface in related with hydraulic conditions. Radionuclides concentration change in effluent solution with time and a concentration distribution of radionuclides adsorbed on the ground surface were obtained from several experimental conditions combining the rate and the duration time of the water flow. The radionuclides concentration in the effluent solution was nearly constant during each experimental period, and was reduced under the condition of lower flow rate. The surface distribution of radionuclides concentration showed two distinctive regions. The one was near the inlet vessel where the concentration was promptly reducing, and the other was following the former where the concentration was nearly constant. The characteristic surface distribution of radionuclides concentration can be explained by a two dimensional diffusion model with a first order adsorption reaction, based on the advection of flow rate distribution in perpendicular direction. (author)

  14. Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow

    Directory of Open Access Journals (Sweden)

    Kahraman Ali

    2012-01-01

    Full Text Available Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 [mm] was experimentally investigated using the PIV technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude numbers were in the range of 0.41 £ Fr £ 0.71 based on the cylinder diameter. It was found that a jet-like flow giving rise to increasing the flow entrainment between the core and wake regions depending on the cylinder diameter was formed between the lower surface of the cylinder and bottom surface of the channel. Vorticity intensity, Reynolds stress correlations and the primary recirculating bubble lengths were grown to higher values with increasing the cylinder diameter. On the other hand, in the case of the lowest level of the jet-like flow emanating from the beneath of the smallest cylinder, the variation of flow characteristics were attenuated significantly in a shorter distance. The variation of the reattachment location of the separated flow to the free-surface is a strong function of the cylinder diameter and the Froude number.

  15. Evaluation of the influence of bypass flow gap distribution on the core hot spot in a prismatic VHTR core

    International Nuclear Information System (INIS)

    Kim, Min-Hwan; Lim, Hong-Sik

    2011-01-01

    Highlights: → A procedure to evaluate the local gap size variation between graphite blocks was developed and applied to a prismatic core VHTR. → The analysis for the core bypass flow and hot spot was carried out based on the calculated gap distributions. → The predicted gap size is large enough to affect the flow distribution in the core. → The bypass gap and flow distributions are closely related to the local hot spot temperature and its location. → The core restraint mechanism preventing outward movement of graphite block reduces the bypass gap size and hot spot temperature. - Abstract: Core bypass flow in VHTR is one of the key issues for core thermal margins and efficiency. The bypass flow in the prismatic core varies during core cycles due to the irradiation shrinkage/swelling and thermal expansion of the graphite blocks. A procedure to evaluate the local gap size variation between graphite blocks was developed and applied to a prismatic core VHTR. The influence of the core restraint mechanism on the bypass flow gap was evaluated. The predicted gap size is as much as 8 mm when the graphite block is exposed to its allowable limit of fast neutron fluence. The analysis for the core bypass flow and hot spot was carried out based on the calculated gap distributions. The results indicate that the bypass gap and flow distributions are closely related to the local hot spot and its location and the core restraint mechanism preventing outward movement of the graphite block by a fastening device reduces the bypass gap size, which results in the decrease of maximum fuel temperature not less than 100 deg. C, when compared to the case without it.

  16. Free surface flows: coalescence, spreading and dewetting

    NARCIS (Netherlands)

    Hernandez Sanchez, J.F.

    2015-01-01

    Capillary and wetting phenomena are an essential part of nature. Its presence is noticed in many circumstances where solid and liquid surfaces come into contact. In this thesis different types of capillary free surface flows are studied. The topics discussed are mainly the coalescence of viscous

  17. Review of coaxial flow gas core nuclear rocket fluid mechanics

    International Nuclear Information System (INIS)

    Weinstein, H.

    1976-01-01

    In a prematurely aborted attempt to demonstrate the feasibility of using a gas core nuclear reactor as a rocket engine, NASA initiated a number of studies on the relevant fluid mechanics problems. These studies were carried out at NASA laboratories, universities and industrial research laboratories. Because of the relatively sudden termination of most of this work, a unified overview was never presented which demonstrated the accomplishments of the program and pointed out the areas where additional work was required for a full understanding of the cavity flow. This review attempts to fulfill a part of this need in two important areas

  18. Review of Constructed Subsurface Flow vs. Surface Flow Wetlands

    International Nuclear Information System (INIS)

    HALVERSON, NANCY

    2004-01-01

    The purpose of this document is to use existing documentation to review the effectiveness of subsurface flow and surface flow constructed wetlands in treating wastewater and to demonstrate the viability of treating effluent from Savannah River Site outfalls H-02 and H-04 with a subsurface flow constructed wetland to lower copper, lead and zinc concentrations to within National Pollutant Discharge Elimination System (NPDES) Permit limits. Constructed treatment wetlands are engineered systems that have been designed and constructed to use the natural functions of wetlands for wastewater treatment. Constructed wetlands have significantly lower total lifetime costs and often lower capital costs than conventional treatment systems. The two main types of constructed wetlands are surface flow and subsurface flow. In surface flow constructed wetlands, water flows above ground. Subsurface flow constructed wetlands are designed to keep the water level below the top of the rock or gravel media, thus minimizing human and ecological exposure. Subsurface flow wetlands demonstrate higher rates of contaminant removal per unit of land than surface flow (free water surface) wetlands, therefore subsurface flow wetlands can be smaller while achieving the same level of contaminant removal. Wetlands remove metals using a variety of processes including filtration of solids, sorption onto organic matter, oxidation and hydrolysis, formation of carbonates, formation of insoluble sulfides, binding to iron and manganese oxides, reduction to immobile forms by bacterial activity, and uptake by plants and bacteria. Metal removal rates in both subsurface flow and surface flow wetlands can be high, but can vary greatly depending upon the influent concentrations and the mass loading rate. Removal rates of greater than 90 per cent for copper, lead and zinc have been demonstrated in operating surface flow and subsurface flow wetlands. The constituents that exceed NPDES limits at outfalls H-02 a nd H

  19. Reactor vessel and core two-phase flow ultrasonic densitometer

    International Nuclear Information System (INIS)

    Arave, A.E.

    1979-01-01

    A local ultrasonic density (LUD) detector has been developed by EG and G Idaho, Inc., at the Idaho National Engineering Laboratory (INEL) for the Loss-of-Fluid Test (LOFT) reactor vessel and core two-phase flow density measurements. The principle of operating the sensor is the change in propagation time of a torsional ultrasonic wave in a metal transmission line as a function of the density of the surrounding media. A theoretical physics model is presented which represents the total propagation time as a function of the sensor modulus of elasticity and polar moment of inertia. Separate effects tests and two-phase flow tests have been conducted to characterize the detector. Tests show the detector can perform in a 343 0 C pressurized water reactor environment and measure the average density of the media surrounding the sensor

  20. Evaluation of core modeling effect on transients for multi-flow zone design of SFR

    International Nuclear Information System (INIS)

    Shin, Andong; Choi, Yong Won

    2016-01-01

    SFR core is composed of different types of assemblies including fuel driver, reflector, blanket, control, safety drivers and other drivers. Modeling of different types of assemblies is inevitable in general. But modeling of core flow zones of with different channels needs a lot of effort and could be a challenge for system code modeling due to its limitation on the number of modeling components. In this study, core modeling effect on SFR transient was investigated with flow-zone model and averaged inner core channel model to improve modeling efficiency and validation of simplified core model for EBR-II loss of flow transient case with the modified TRACE code for SFRs. Core modeling effect on the loss flow transient was analyzed with flow-zoned channel model, single averaged inner core model and highest flow channel with averaged inner core channel model for EBR-II SHRT-17 test core. Case study showed that estimations of transient pump and channel flow as well as channel outlet temperatures were similar for all cases macroscopically. Comparing the result of the base case (flow-zone channel inner core model) and the case 2 (highest flow channel considered averaged inner core channel model), flow and channel outlet temperature response were closer than the case1 (single averaged inner core model)

  1. Evaluation of core modeling effect on transients for multi-flow zone design of SFR

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Andong; Choi, Yong Won [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2016-10-15

    SFR core is composed of different types of assemblies including fuel driver, reflector, blanket, control, safety drivers and other drivers. Modeling of different types of assemblies is inevitable in general. But modeling of core flow zones of with different channels needs a lot of effort and could be a challenge for system code modeling due to its limitation on the number of modeling components. In this study, core modeling effect on SFR transient was investigated with flow-zone model and averaged inner core channel model to improve modeling efficiency and validation of simplified core model for EBR-II loss of flow transient case with the modified TRACE code for SFRs. Core modeling effect on the loss flow transient was analyzed with flow-zoned channel model, single averaged inner core model and highest flow channel with averaged inner core channel model for EBR-II SHRT-17 test core. Case study showed that estimations of transient pump and channel flow as well as channel outlet temperatures were similar for all cases macroscopically. Comparing the result of the base case (flow-zone channel inner core model) and the case 2 (highest flow channel considered averaged inner core channel model), flow and channel outlet temperature response were closer than the case1 (single averaged inner core model)

  2. 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.

  3. A study on bypass flow gap distribution in a prismatic VHTR core

    International Nuclear Information System (INIS)

    Kim, M. H.; Jo, C. K.; Lim, H. S.

    2010-01-01

    Core bypass flow in VHTR is one of the key issues for core thermal margins and efficiency. The bypass flow in the prismatic core varies during core cycles due to the irradiation shrinkage and thermal expansion of the graphite blocks. A procedure to evaluate the local gap size variation between graphite blocks was developed and applied to a prismatic core VHTR. The influence of the core restraint mechanism on the bypass flow gap was evaluated. The predicted gap size is as much as 8 mm when the graphite block is exposed to its allowable limit of irradiation fluence. The analysis for the core bypass flow and hot spot was carried out based on the calculated gap distributions. The results indicate that the bypass flow and the location of core hot spots are closely related and a measure to reduce the bypass flow is necessary. (authors)

  4. Origin of metallic surface core-level shifts

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Abrikosov, I. A.

    1995-01-01

    The unique property of the open 4f energy shell in the lanthanide metals is used to show that the initial-state energy shift gives an insufficient description of surface core-level shifts. Instead a treatment, which fully includes the final-state screening, account for the experimentally observed...

  5. Combustion of metal agglomerates in a solid rocket core flow

    Science.gov (United States)

    Maggi, Filippo; Dossi, Stefano; DeLuca, Luigi T.

    2013-12-01

    The need for access to space may require the use of solid propellants. High thrust and density are appealing features for different applications, spanning from boosting phase to other service applications (separation, de-orbiting, orbit insertion). Aluminum is widely used as a fuel in composite solid rocket motors because metal oxidation increases enthalpy release in combustion chamber and grants higher specific impulse. Combustion process of metal particles is complex and involves aggregation, agglomeration and evolution of reacting particulate inside the core flow of the rocket. It is always stated that residence time should be enough in order to grant complete metal oxidation but agglomerate initial size, rocket grain geometry, burning rate, and other factors have to be reconsidered. New space missions may not require large rocket systems and metal combustion efficiency becomes potentially a key issue to understand whether solid propulsion embodies a viable solution or liquid/hybrid systems are better. A simple model for metal combustion is set up in this paper. Metal particles are represented as single drops trailed by the core flow and reacted according to Beckstead's model. The fluid dynamics is inviscid, incompressible, 1D. The paper presents parametric computations on ideal single-size particles as well as on experimental agglomerate populations as a function of operating rocket conditions and geometries.

  6. Polygon formation and surface flow on a rotating fluid surface

    DEFF Research Database (Denmark)

    Bergmann, Raymond; Tophøj, Laust Emil Hjerrild; Homan, T. A. M.

    2011-01-01

    We present a study of polygons forming on the free surface of a water flow confined to a stationary cylinder and driven by a rotating bottom plate as described by Jansson et al. (Phys. Rev. Lett., vol. 96, 2006, 174502). In particular, we study the case of a triangular structure, either completely...... there the symmetry breaking proceeds like a low-dimensional linear instability. We show that the circular state and the unstable manifold connecting it with the polygon solution are universal in the sense that very different initial conditions lead to the same circular state and unstable manifold. For a wet triangle......, we measure the surface flows by particle image velocimetry (PIV) and show that there are three vortices present, but that the strength of these vortices is far too weak to account for the rotation velocity of the polygon. We show that partial blocking of the surface flow destroys the polygons and re...

  7. Preliminary Estimation of Local Bypass Flow Gap Sizes for a Prismatic VHTR Core

    International Nuclear Information System (INIS)

    Kim, Min Hwan; Jo, Chang Keun; Lee, Won Jae

    2009-01-01

    The Very High Temperature Reactor (VHTR) has been selected for the Nuclear Hydrogen Development and Demonstration (NHDD) project. In the VHTR design, core bypass flow has been one of key issues for core thermal margins and target temperature of the core outlet. The core bypass flow in the prismatic VHTR varies with the core life due to the irradiation shrinkage/ swelling and thermal expansion of the graphite blocks, which could be a significant proportion of the total core flow. Thus, accurate prediction of the bypass flow is of major importance in assuring the core thermal margin. To predict the bypass flow, first of all, local gap sizes between graphite blocks in the core should be determined. The objectives of this work are to develop a methodology for determining the gap sizes and to perform a preliminary evaluation for a reference reactor

  8. Bypass Flow and Hot Spot Analysis for PMR200 Block-Core Design with Core Restraint Mechanism

    International Nuclear Information System (INIS)

    Lim, Hong Sik; Kim, Min Hwan

    2009-01-01

    The accurate prediction of local hot spot during normal operation is important to ensure core thermal margin in a very high temperature gas-cooled reactor because of production of its high temperature output. The active cooling of the reactor core determining local hot spot is strongly affected by core bypass flows through the inter-column gaps between graphite blocks and the cross gaps between two stacked fuel blocks. The bypass gap sizes vary during core life cycle by the thermal expansion at the elevated temperature and the shrinkage/swelling by fast neutron irradiation. This study is to investigate the impacts of the variation of bypass gaps during core life cycle as well as core restraint mechanism on the amount of bypass flow and thus maximum fuel temperature. The core thermo fluid analysis is performed using the GAMMA+ code for the PMR200 block-core design. For the analysis not only are some modeling features, developed for solid conduction and bypass flow, are implemented into the GAMMA+ code but also non-uniform bypass gap distribution taken from a tool calculating the thermal expansion and the shrinkage/swell of graphite during core life cycle under the design options with and without core restraint mechanism is used

  9. Ab initio surface core-level shifts and surface segregation energies

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    We have calculated the surface core-level energy shifts of the 4d and 5d transition metals by means of local-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method. Final-state effects are included by treating the core-ionized atom as an impurity located in...

  10. 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).

  11. CFD Analysis on a Core Outlet Flow through the Fuel Alignment Plant of SMART

    International Nuclear Information System (INIS)

    Kim, Y. I.; Bae, Y. M.; Kim, K. K.

    2014-01-01

    CFD (Computational Fluid Dynamics) simulations were performed to confirm the core flow distribution for SMART, which acquired standard design approval in 2012. In this paper, CFD simulation is also used to calculate the pressure distribution of a core outlet, a Fuel Alignment Plate (FAP), for SMART. In SMART, the fluid discharged from the Steam Generator comes into a Flow Mixing Header Assembly (FMHA), and is rearranged and split into a very fine size. The FMHA is greatly important for enhancing the flow distribution of a downcomer during a normal operation, transient, and even accidents. Then, the fluid discharged from the FMHA flows into the core upstream through flow skirt holes. The Low Core Support Plate (LCSP) reallocates the flow introducing into the inlet core from the core upstream. The deviation of flow distribution becomes smaller or almost disappears by LCSP holes having relatively large loss coefficient compared to the downstream flow deviation. In an open core, the flow deviation at the core inlet region is diminished by cross flow as it goes upward. Near the core outlet, the flow distribution can be distorted by the influence of a Fuel Alignment Plate (FAP) installed above the fuels. In this paper, the effect of the core outlet flow structure such as the FAP holes of SMART is investigated. Before the calculation, the influences of mesh size and turbulence models are inspected. CFD simulations were performed to investigate the effect of FAP flow holes on the core outlet flow of SMART. As a preliminary study, the dependency of the mesh size and turbulence models was tested; a fine grid was applied, the effect of which is negligible, and the core outlet flow is not sensitive to the turbulence models. In brief, the flow resistance of FAP is less than 15% of that of the fuel assemblies. The flow resistance deviation between two flow path patterns is less than 1% of that of active core. Even two flow path patterns located at the downstream location of the

  12. Surface-acoustic-wave (SAW) flow sensor

    Science.gov (United States)

    Joshi, Shrinivas G.

    1991-03-01

    The use of a surface-acoustic-wave (SAW) device to measure the rate of gas flow is described. A SAW oscillator heated to a suitable temperature above ambient is placed in the path of a flowing gas. Convective cooling caused by the gas flow results in a change in the oscillator frequency. A 73-MHz oscillator fabricated on 128 deg rotated Y-cut lithium niobate substrate and heated to 55 C above ambient shows a frequency variation greater than 142 kHz for flow-rate variation from 0 to 1000 cu cm/min. The output of the sensor can be calibrated to provide a measurement of volume flow rate, pressure differential across channel ports, or mass flow rate. High sensitivity, wide dynamic range, and direct digital output are among the attractive features of this sensor. Theoretical expressions for the sensitivity and response time of the sensor are derived. It is shown that by using ultrasonic Lamb waves propagating in thin membranes, a flow sensor with faster response than a SAW sensor can be realized.

  13. Effect of the design change of the LSSBP on core flow distribution of APR+ Reactor

    International Nuclear Information System (INIS)

    Kim, Kihwan; Euh, Dong-Jin; Choi, Hae-Seob; Kwon, Tae-Soon

    2014-01-01

    The uniform core inlet flow distribution of an Advanced Power Reactor Plus (APR+) is required to prevent the failure rate of the HIPER fuel assembly and improve the core thermal margin. KEPCO-E and C and KAERI proposed a design change of the Lower Support Structure Bottom Plate (LSSBP), since the core flow rates were intense near the outer region of the intact LSSBP in a previous study. In this study, an experiment was carried out to evaluate the effect of the design change of the LSSBP on the core flow distribution using the APR+ Core Flow and Pressure (ACOP) test facility. The results showed great improvement on the core flow distribution under a 4-pump balanced flow condition. Under the 4-pump balanced flow condition, fifteen tests were repeated using the ACOP test facility to verify the effect of the 50% blocked flow area at the outer region of the LSSBP on the core inlet flow distribution. The profiles of the core inlet mass flow rates were analyzed using ensemble averaged values, and compared with that of the intact LSSBP. The results showed great improvement for the overall core region. The change in design of the LSSBP is expected to improve the hydraulic performance of an APR+ reactor

  14. CFD analysis of flow distribution at the core inlet of SMART

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Youngmin, E-mail: ybae@kaeri.re.kr [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Young In; Park, Cheon Tae [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2013-05-15

    Highlights: ► Core inlet flow distribution of system-integrated modular advanced reactor (SMART) is numerically investigated. ► Effects of mesh resolution, turbulence model, Reynolds number, and inflow condition are examined. ► Numerical results show that lower core support plate effectively distributes the flow at the core inlet of SMART. -- Abstract: This study numerically investigates the flow distribution at the core inlet region of the system-integrated modular advanced reactor (SMART). The single-phase turbulent flow is computed by the commercial CFD code, Fluent 12.0 on the computational domain consisting of three main parts: fuel assemblies, a lower core support plate, and a flow skirt. Simulations are carried out with different mesh resolutions, turbulence models, and upstream boundary conditions. The CFD results show that the flow distribution at the core inlet is almost identical for the two Reynolds numbers and turbulence models tested here, and the effect of mesh refinement on the flow distribution at the core inlet is negligible. It is also found that under a uniform upstream boundary condition, the maximum difference in mass flow rate between the fuel assemblies is less than 2%, while it slightly increases to 2.3% under a non-uniform condition. These results consequently indicate that the present design of the lower core support plate effectively distributes the flow at the core inlet of SMART, even when the flow discharged from the upstream has a certain degree of non-uniformity.

  15. Accuracy of small diameter sheathed thermocouples for the core flow test loop

    International Nuclear Information System (INIS)

    Anderson, R.L.; Kollie, T.G.

    1979-04-01

    This report summarizes the research and development on 0.5-mm-diameter, compacted, metal sheathed thermocouples. The objectives of this research effort have been: to identify and analyze the sources of temperature measurement errors in the use of 0.5-mm-diameter sheathed thermocouples to measure the surface temperature of the cladding of fuel-rod simulators in the Core Flow Test Loop (CFTL) at ORNL; to devise methods for reducing or correcting for these temperature measurement errors; to estimate the overall temperature measurement uncertainties; and to recommend modifications in the manufacture, installation, or materials used to minimize temperature measurement uncertainties in the CFTL experiments

  16. Effects of lower plenum flow structure on core inlet flow of ABWR

    International Nuclear Information System (INIS)

    Watanabe, Shun; Abe, Yutaka; Kaneko, Akiko; Watanabe, Fumitoshi; Tezuka, Kenichi

    2010-01-01

    The evaluation of coolant flow structure at a lower plenum of an advanced boiling water reactor (ABWR) in which there are many structures is very important in order to improve generating power. Although the simulation results by CFD (Computational Fluid Dynamics) codes can predict such complicated flow in the lower plenum, it is required to establish the database of flow structure in lower plenum of ABWR experimentally for the benchmark of the CFD codes. In the model of the lower plenum, we measured velocity profiles with LDV and PIV. And differential pressure of constructed model is measured with differential pressure instrument. It was identified that the velocity and differential pressure profiles also showed the tendency to be flat in the core inlet. Moreover, vortexes were observed around side entry orifice by PIV measurement. (author)

  17. Are atmospheric surface layer flows ergodic?

    Science.gov (United States)

    Higgins, Chad W.; Katul, Gabriel G.; Froidevaux, Martin; Simeonov, Valentin; Parlange, Marc B.

    2013-06-01

    The transposition of atmospheric turbulence statistics from the time domain, as conventionally sampled in field experiments, is explained by the so-called ergodic hypothesis. In micrometeorology, this hypothesis assumes that the time average of a measured flow variable represents an ensemble of independent realizations from similar meteorological states and boundary conditions. That is, the averaging duration must be sufficiently long to include a large number of independent realizations of the sampled flow variable so as to represent the ensemble. While the validity of the ergodic hypothesis for turbulence has been confirmed in laboratory experiments, and numerical simulations for idealized conditions, evidence for its validity in the atmospheric surface layer (ASL), especially for nonideal conditions, continues to defy experimental efforts. There is some urgency to make progress on this problem given the proliferation of tall tower scalar concentration networks aimed at constraining climate models yet are impacted by nonideal conditions at the land surface. Recent advancements in water vapor concentration lidar measurements that simultaneously sample spatial and temporal series in the ASL are used to investigate the validity of the ergodic hypothesis for the first time. It is shown that ergodicity is valid in a strict sense above uniform surfaces away from abrupt surface transitions. Surprisingly, ergodicity may be used to infer the ensemble concentration statistics of a composite grass-lake system using only water vapor concentration measurements collected above the sharp transition delineating the lake from the grass surface.

  18. Free surface flows under compensated gravity conditions

    CERN Document Server

    Dreyer, Miachel E

    2007-01-01

    This book considers the behavior of fluids in a low-gravity environment with special emphasis on application in PMD (propellant management device) systems . In the compensated gravity environment of a spacecraft, the hydrostatic pressure decreases to very low values depending on the residual acceleration, and surface tension forces become dominant. Consequently, surface tension can be used to transport and position liquids if the residual acceleration and the resulting hydrostatic pressure are small compared to the capillary pressure. One prominent application is the use of PMDs in surface-tension satellite tanks. PMDs must ensure that the tank outlet is covered with liquid whenever outflow is demanded. Furthermore, PMDs are used to ensure expulsion and refilling of tanks for liquids and gases for life support, reactants, and experiment supplies. Since most of the PMD designs are not testable on ground and thus rely on analytical or numerical concepts, this book treats three different flow problems with analy...

  19. Core surface magnetic field evolution 2000–2010

    DEFF Research Database (Denmark)

    Finlay, Chris; Jackson, A.; Gillet, N.

    2012-01-01

    harmonics up to degree and order 24 and a temporal parametrization of sixth‐order B‐splines with 0.25 yr knot spacing is employed. Models were constructed by minimizing an absolute deviation measure of misfit along with measures of spatial and temporal complexity at the core surface. We investigate...... is weaker. Rapid field evolution is observed under the eastern Indian Ocean associated with the growth and drift of an intense low latitude flux patch. We also find that the present axial dipole decay arises from a combination of subtle changes in the southern hemisphere field morphology....

  20. 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.

  1. Effects of non-uniform core flow on peak cladding temperature: MOXY/SCORE sensitivity calculations

    Energy Technology Data Exchange (ETDEWEB)

    Chang, S.C.

    1979-08-15

    The MOXY/SCORE computer program is used to evaluate the potential effect on peak cladding temperature of selective cooling that may result from a nonuniform mass flux at the core boundaries during the blowdown phase of the LOFT L2-4 test. The results of this study indicate that the effect of the flow nonuniformity at the core boundaries will be neutralized by a strong radial flow redistribution in the neighborhood of core boundaries. The implication is that the flow nonuniformity at the core boundaries has no significant effect on the thermal-hydraulic behavior and cladding temperature at the hot plane.

  2. Effects of non-uniform core flow on peak cladding temperature: MOXY/SCORE sensitivity calculations

    International Nuclear Information System (INIS)

    Chang, S.C.

    1979-01-01

    The MOXY/SCORE computer program is used to evaluate the potential effect on peak cladding temperature of selective cooling that may result from a nonuniform mass flux at the core boundaries during the blowdown phase of the LOFT L2-4 test. The results of this study indicate that the effect of the flow nonuniformity at the core boundaries will be neutralized by a strong radial flow redistribution in the neighborhood of core boundaries. The implication is that the flow nonuniformity at the core boundaries has no significant effect on the thermal-hydraulic behavior and cladding temperature at the hot plane

  3. Synthesis of Au@Ag core-shell nanocubes containing varying shaped cores and their localized surface plasmon resonances.

    Science.gov (United States)

    Gong, Jianxiao; Zhou, Fei; Li, Zhiyuan; Tang, Zhiyong

    2012-06-19

    We have synthesized Au@Ag core-shell nanocubes containing Au cores with varying shapes and sizes through modified seed-mediated methods. Bromide ions are found to be crucial in the epitaxial growth of Ag atoms onto Au cores and in the formation of the shell's cubic shape. The Au@Ag core-shell nanocubes exhibit very abundant and distinct localized surface plasmon resonance (LSPR) properties, which are core-shape and size-dependent. With the help of theoretical calculation, the physical origin and the resonance mode profile of each LSPR peak are identified and studied. The core-shell nanocrystals with varying shaped cores offer a new rich category for LSPR control through the plasmonic coupling effect between core and shell materials.

  4. Numerical solution of heat transfer process in a prismatic VHTR core accompanying bypass and cross flows

    International Nuclear Information System (INIS)

    Wang, Li; Liu, Qiusheng; Fukuda, Katsuya

    2016-01-01

    Highlights: • Three-dimensional CFD analysis is conducted for the thermal analysis in the reactor core. • Hot spot temperature, coolant channel outlet temperature distribution are affected by bypass flow. • Bypass gap size has significant influence on temperature and flow distribution in the core. • Cross flow has some effect on the temperature distribution of the coolant in the core due to flow mixing in the cross gaps. - Abstract: Bypass flow and cross flow gaps both exist in the core of a very high temperature gas-cooled reactor (VHTR), which is inevitable owing to tolerances in manufacturing, thermal expansion and irradiation shrinkage. The coolant mass flow rate distribution, temperature distribution, and hot spot temperature are significantly affected by bypass and cross flows. In the present study, three-dimensional CFD analysis is conducted for thermal analysis of the reactor core. A validation study for the turbulence model is performed by comparing the friction coefficient with published correlations. A sensitivity study of the near wall mesh is conducted to ensure mesh quality. Parametric studies are performed by changing the size of the bypass and cross gaps using a one-twelfth sector of a fuel block. Simulation results show the influence of the bypass gap size on temperature distribution and coolant mass flow rate distribution in the prismatic core. It is shown that the maximum fuel and coolant channel outlet temperatures increase with an increase in the gap size, which may lead to a structural risk to the fuel block. The cross flow is divided into two types: the cross flow from the bypass gap to the coolant channels and the cross flow from the high-pressure coolant channels to low-pressure coolant channels. These two types of flow have an opposing influence on the temperature gradient. It is found that the presence of the cross flow gaps may have a significant effect on the distribution of the coolant in the core due to flow mixing in the

  5. PEG-stabilized core-shell surface-imprinted nanoparticles.

    Science.gov (United States)

    Moczko, Ewa; Guerreiro, Antonio; Piletska, Elena; Piletsky, Sergey

    2013-08-06

    Here we present a simple technique to produce target-specific molecularly imprinted polymeric nanoparticles (MIP NPs) and their surface modification in order to prevent the aggregation process that is ever-present in most nanomaterial suspensions/dispersions. Specifically, we studied the influence of surface modification of MIP NPs with polymerizable poly(ethylene glycol) on their degree of stability in water, in phosphate buffer, and in the presence of serum proteins. Grafting a polymer shell on the surface of nanoparticles decreases the surface energy, enhances the polarity, and as a result improves the dispersibility, storage, and colloidal stability as compared to those of core (unmodified) particles. Because of the unique solid-phase approach used for synthesis, the binding sites of MIP NPs are protected during grafting, and the recognition properties of nanoparticles are not affected. These results are significant for developing nanomaterials with selective molecular recognition, increased biocompatibility, and stability in solution. Materials synthesized this way have the potential to be used in a variety of technological fields, including in vivo applications such as drug delivery and imaging.

  6. Fabrication of a polyvinylidene difluoride fiber with a metal core and its application as directional air flow sensor

    Science.gov (United States)

    Bian, Yixiang; Liu, Rongrong; Hui, Shen

    2016-09-01

    We fabricated a sensitive air flow detector that mimic the sensing mechanism found at the tail of some insects. [see Y. Yang, A. Klein, H. Bleckmann and C. Liu, Appl. Phys. Lett. 99(2) (2011); J. J. Heys, T. Gedeon, B. C. Knott and Y. Kim, J. Biomech. 41(5), 977 (2008); J. Tao and X. Yu, Smart Mat. Struct. 21(11) (2012)]. Our bionic airflow sensor uses a polyvinylidene difluoride (PVDF) microfiber with a molybdenum core which we produced with the hot extrusion tensile method. The surface of the fiber is partially coated with conductive silver adhesive that serve as surface electrodes. A third electrode, the metal core is used to polarize polyvinylidene difluoride (PVDF) under the surface electrodes. The cantilever beam structure of the prepared symmetric electrodes of metal core piezoelectric fiber (SMPF) is used as the artificial hair airflow sensor. The surface electrodes are used to measure output voltage. Our theoretical and experimental results show that the SMPF responds fast to air flow changes, the output charge has an exponential correlation with airflow velocity and a cosine relation with the direction of airflow. Our bionic airflow sensor with directional sensing ability can also measure air flow amplitude. [see H. Droogendijk, R. G. P. Sanders and G. J. M. Krijnen, New J. Phys. 15 (2013)]. By using two surface electrodes, our sensing circuit further improves sensitivity.

  7. Identification of Columbia River basalt flows from deep cores in the Pasco Basin based on trace element abundances

    International Nuclear Information System (INIS)

    Fruchter, J.S.; Rancitelli, L.A.

    1976-01-01

    Samples of basalt from three deep core holes drilled in the Pasco Basin, Washington (DDH-3, DH-4, DH-5) were analyzed by instrumental neutron activation (INAA) for up to fifteen trace and major elements. These analyses were used to assign each basalt flow to one of a series of previously defined chemical types of the Columbia River Basalt Group. All of the flows except the two flows at the bottom of well DDH-3 were clearly assignable to one of the defined chemical types. These two flows apparently represent new, as yet undefined chemical types. Average values and standard deviations for compositions of each of the chemical types found in the three wells are presented along with two-element variation diagrams for the geochemically important pair La-Cr, La-Fe, La-Th and La-Sc. The assignment of the flows to known chemical types accomplished in this study was very helpful in relating the basalts in the core holes to stratigraphically defined basalt flows in surface sections. A correlation diagram relating the flows in the core holes to one another on the basis of chemical type is presented

  8. Evaluation of Core Bypass Flow in the Prismatic VHTR with a Multi-block Experiment

    International Nuclear Information System (INIS)

    Lee, Jeong Hun; Yoon, Su Jong; Park, Goon Cherl; Kim, Min Hwan

    2010-01-01

    The core of Prismatic Modular Reactor (PMR) consists of assemblies of hexagonal graphite fuel and reflector elements. The core bypass flow of Very High Temperature Reactor (VHTR) is defined as the core flow that does not pass through the coolant channels but passes through the bypass gap between fuel elements. The increase in bypass flow makes the decrease in effective coolant flow. Since the core bypass flow has a negative impact on safety and efficiency of VHTR, core bypass phenomena have to be investigated to improve the core thermal margin of VHTR. For this purpose, the international project, I-NERI project, has been carried out since 2008. I-NERI project is collaborative project that KAERI and SNU of Korea side and INL, ANL and TAMU of U.S side are involved. In order to evaluate the core bypass flow, the multicolumn and multi-layer experimental facility is designed by SNU. In this experiment, the effect of cross-flow and local variation of bypass gap on the bypass flow distribution is investigated. Furthermore, the experimental data will be used for validation of CFD code or thermal hydraulic analysis codes such as GAMMA or GAS-NET

  9. Predictions of the Bypass Flows in the HTR-PM Reactor Core

    International Nuclear Information System (INIS)

    Sun Jun; Chen Zhipeng; Zheng Yanhua; Shi Lei; Li Fu

    2014-01-01

    In the HTR-PM reactor core, the basic structure materials are large amount of graphite reflectors and carbon bricks. Small gaps among those graphite and carbon bricks are widespread in the reactor core so that the cold helium flow may be bypassed and not completely heated. The bypass flows in relative lower temperature would change the flow and temperature distributions in the reactor core, therefore, the accurate prediction of bypass flows need to be carried out carefully to evaluate the influence to the reactor safety. Based on the characteristics of the bypass flow problem, hybrid method of the flow network and the CFD tools was employed to represent the connections and calculate flow distributions of all the main flow and bypass flow paths. In this paper, the hybrid method was described and applied to specific bypass flow problem in the HTR-PM. Various bypass flow paths in the HTR-PM were reviewed, figured out, and modeled by the flow network and the CFD methods, including the axial vertical gaps in the side reflectors, control rod channels, absorber sphere channels and radial gap flow through keys around the hot helium plenum. The bypass flow distributions and its flow rate ratio to the total flow rate in the primary loop were also calculated, discussed and evaluated. (author)

  10. Near-field flow structures about subcritical surface roughness

    Science.gov (United States)

    Doolittle, Charles J.; Drews, Scott D.; Goldstein, David B.

    2014-12-01

    Laminar flow over a periodic array of cylindrical surface roughness elements is simulated with an immersed boundary spectral method both to validate the method for subsequent studies and to examine how persistent streamwise vortices are introduced by a low Reynolds number roughness element. Direct comparisons are made with prior studies at a roughness-based Reynolds number Rek (=U(k) k/ν) of 205 and a diameter to spanwise spacing ratio d/λ of 1/3. Downstream velocity contours match present and past experiments very well. The shear layer developed over the top of the roughness element produces the downstream velocity deficit. Upstream of the roughness element, the vortex topology is found to be consistent with juncture flow experiments, creating three cores along the recirculation line. Streamtraces stemming from these upstream cores, however, have unexpectedly little effect on the downstream flowfield as lateral divergence of the boundary layer quickly dissipates their vorticity. Long physical relaxation time of the recirculating wake behind the roughness remains a prominent issue for simulating this type of flowfield.

  11. Analysis of liquid metal MHD flow in multiple adjacent ducts using an iterative method to solve the core flow equations

    International Nuclear Information System (INIS)

    McCarthy, K.A.; Abdou, M.A.

    1991-01-01

    A computationally fast and efficient method for analyzing MHD flow at high Hartmann number and interaction parameter is presented and used to analyze a multiple duct geometry. This type of geometry is of practical interest in fusion applications. Because the Hartmann number and interaction parameter are generally large in fusion applications, the inertial and viscous terms in the Navier-Stokes equation can often be neglected in the core flow region, making this equation linear. In addition, because the magnetic fields in a fusion reactor vary slowly and the magnetic Reynolds number is small, the induced magnetic field can be neglected. The resulting equations representing core flow have certain characteristics which make it possible to reduce them to two dimensional without losing the three dimensional characteristics. The method which has been developed is an 'iterative' method. A velocity profile is assumed, then Ohm's law and the current conservation equation are combined and used to solve for the potential distribution in a plane in the fluid, and in a surface in the duct wall. The potential variation along magnetic field lines is checked, and if necessary, the velocities are adjusted. This procedure is repeated until the potentials along field lines vary to within a specified error. The analysis of the multiple duct geometry shows the importance of global effects. The results of two basic cases are presented. In the first, the average velocity in each duct is the same, but the wall conductance ratios of the walls perpendicular to the magnetic field vary from duct to duct. The total pressure drop in the electrically connected ducts was greater than or equal to the total pressure drop in the same ducts electrically isolated. In addition, the velocity profile in the ducts can be significantly affected by the presence of neighboring ducts. (orig./AH)

  12. Development of flow network analysis code for block type VHTR core by linear theory method

    International Nuclear Information System (INIS)

    Lee, J. H.; Yoon, S. J.; Park, J. W.; Park, G. C.

    2012-01-01

    VHTR (Very High Temperature Reactor) is high-efficiency nuclear reactor which is capable of generating hydrogen with high temperature of coolant. PMR (Prismatic Modular Reactor) type reactor consists of hexagonal prismatic fuel blocks and reflector blocks. The flow paths in the prismatic VHTR core consist of coolant holes, bypass gaps and cross gaps. Complicated flow paths are formed in the core since the coolant holes and bypass gap are connected by the cross gap. Distributed coolant was mixed in the core through the cross gap so that the flow characteristics could not be modeled as a simple parallel pipe system. It requires lot of effort and takes very long time to analyze the core flow with CFD analysis. Hence, it is important to develop the code for VHTR core flow which can predict the core flow distribution fast and accurate. In this study, steady state flow network analysis code is developed using flow network algorithm. Developed flow network analysis code was named as FLASH code and it was validated with the experimental data and CFD simulation results. (authors)

  13. Evaluation of compatibility of flowing liquid lithium curtain for blanket with core plasma in fusion reactors

    International Nuclear Information System (INIS)

    Deng Baiquan; Huang Jinhua; Peng Lilin; Yan Jiancheng

    2003-01-01

    A global model analysis of the compatibility of flowing liquid lithium curtain for blanket with core plasma has been performed. The relationships between the surface temperature of lithium curtain and mean effective plasma charges, fuel dilution and produced fusion power have been obtained. Results show that under normal circumstances, the evaporation of liquid lithium does not affect Z eff seriously, but affects fuel dilution and fusion power sensitively. The authors have investigated the relationships between the flow velocity of liquid lithium and its surface temperature rise based on the conditions of the option II of the fusion experimental breeder (FEB-E) design with reversed shear configuration and fairly high power density. The authors concluded that the effects of evaporation from liquid lithium curtain for FEB-E on plasma are negligible even if the flow velocity of liquid lithium is as low as 0.5 m·s -1 . Finally, the sputtering yield of liquid lithium saturated by hydrogen isotopes is briefly discussed

  14. Characterisation of the core poloidal flow at ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Lebschy, Alexander [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Physik-Department E28, Technische Universitaet Muenchen, D-85748 Garching (Germany); McDermott, Rachael M.; Geiger, Benedikt; Cavedon, Marco; Dunne, Michael G.; Dux, Ralph; Fischer, Rainer; Kappatou, Athina; McCarthy, Patrick J.; Viezzer, Eleonora [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Collaboration: the ASDEX Upgrade Team

    2016-07-01

    Plasma rotation has a strong influence on the transport of heat, particles, and momentum in fusion plasmas via a variety of mechanisms, for example, by the stabilization of modes and the suppression of plasma turbulence. In tokamaks, the toroidal rotation (u{sub tor}) is essentially a free parameter that is usually dominated by the external momentum input from neutral beams used to heat the plasma. The poloidal rotation (u{sub pol}), on the other hand, is strongly damped and is predicted to remain at Neoclassical (NC) levels of a few km/s. Measuring the inboard-outboard asymmetry of u{sub tor} with charge exchange recombination spectroscopy enables an indirect measurement of u{sub pol} and, hence, the measurement of the complete plasma flow on a flux surface. In order to characterise the nature of u{sub pol} at ASDEX Upgrade a poloidal rotation database has been built that contains a large variation in the parameters that, according to NC theory, drive u{sub pol}; namely, the main ion temperature and density gradients and collisionality. Initial results from this database and a detailed comparison of u{sub pol} to NC theory in interesting plasma scenarios, are presented in this poster.

  15. Heat transfer effect of an extended surface in downward-facing subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Abdul R., E-mail: khan@vis.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Erkan, Nejdet, E-mail: erkan@vis.t.u-tokyo.ac.jp [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki, 319-1188 (Japan); Okamoto, Koji, E-mail: okamoto@n.t.u-tokyo.ac.jp [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki, 319-1188 (Japan)

    2015-12-15

    Highlights: • Compare downward-facing flow boiling results from bare and extended surfaces. • Upstream and downstream temperatures were measured on the extended surface. • Downstream temperatures exceed upstream temperatures for all flow rates. • Bubble accumulation occurs downstream on extended surface. • Extended surface heat transfer lower than bare surface as flow rate reduced. - Abstract: New BWR containment designs are considering cavity flooding as an accident management strategy. Unlike the PWR, the BWR has many Control Rod Guide Tube (CRGT) penetrations in the lower head. During a severe accident scenario with core melt in the lower plenum along with cavity flooding, the penetrations may affect the heat transfer on the ex-vessel surface and disrupt fluid flow during the boiling process. A small-scale experiment was performed to investigate the issues existing in downward-facing boiling phenomenon with an extended surface. The results were compared with a bare (flat) surface. The mass flux of 244 kg/m{sup 2} s, 215 kg/m{sup 2} s, and 177 kg/m{sup 2} s were applied in this study. CHF conditions were observed only for the 177 kg/m{sup 2} s case. The boiling curves for both types of surfaces and all flow rates were obtained. The boiling curves for the highest flow rate showed lower surface temperatures for the extended surface experiments when compared to the bare surface. The downstream location on the extended surface yielded the highest surface temperatures as the flow rate was reduced. The bubble accumulation and low velocity in the wake produced by flow around the extended surface was believed to have caused the elevated temperatures in the downstream location. Although an extended surface may enhance the overall heat transfer, a reduction in the local heat transfer was observed in the current experiments.

  16. Experimental Investigation on Cross Flow of Wedge-shaped Gap in the core of Prismatic VHTR

    International Nuclear Information System (INIS)

    Lee, Jeong Hun; Park, Goon Cherl; Cho, Hyoung Kyu; Yoon, Su Jong

    2014-01-01

    The core of the PMR type reactor consists of assemblies of hexagonal graphite blocks. The graphite blocks have lots of advantages for neutron economy and high temperature structural integrity. The height and flat-to-flat width of fuel bock are 793 mm and 360 mm, respectively. Each block has 108 coolant channels of which the diameter is 16 mm. And there are gaps between blocks not only vertically but also horizontally for reloading of the fuel elements. The vertical gap induces the bypass flow and through the horizontal gap the cross flow is formed. Since the complicated flow distribution occurs by the bypass flow and cross flow, flow characteristics in the core of the PMR reactor cannot be treated as a simple pipe flow. The fuel zone of the PMR core consists of multiple layers of fuel blocks. The shape change of the fuel blocks could be caused by the thermal expansion and fast-neutron induced shrinkage. It could make different axial shrinkage of fuel block and this leads to wedge-shaped gaps between two stacked fuel blocks. The cross flow is often considered as a leakage flow through the horizontal gap between stacked fuel blocks and it complicates the flow distribution in the reactor core by connecting the coolant channel and the bypass gap. Moreover, the cross flow could lead to uneven coolant distribution and consequently cause superheating of individual fuel element zones with increased fission product release. Since the core cross flow has a negative impact on safety and efficiency of VHTR, core cross flow phenomena have to be investigated to improve the core thermal margin of VHTR. To develop the cross flow loss coefficient model for determination of the flow distribution for PMR core analysis codes, study on cross flow for PMR200 core is essential. In particular, to predict the amount of flow through the cross flow gap, obtaining accurate flow loss coefficient is important. In this study, the full-scale cross flow experimental facility was constructed to

  17. Study and analysis for the flow-induced vibration of the core barrel of a PWR

    International Nuclear Information System (INIS)

    Yao Weida; Shi Guolin; Jiang Nanyan

    1989-01-01

    The resemblance criteria are derived and a test model is designed by applying the flow-soild coupling theory. After having completed the model analysis of the pressurized water reactor (PWR) core barrel in an 1:10 model, the dynamic characteristics are obtained. In an 1:5 reactor model with a hydraulic closed loop, the hydraulic vibration tests of the core barrel are performed, and the relations between the flow rate and the flow-induced pulse pressure on core barrel, acceleration and strain signals have been measured. The corresponding responses and a group of computational equations for hydraulic vibration are derived from these two experiments. The computational hydraulic vibration responses for core barrel in Qinshan Nuclear Power Plant are in good agreement with the test results, and it shows that the core barrel is safe within its lifetime of 30 years

  18. Structural organization of the quiescent core region in a turbulent channel flow

    International Nuclear Information System (INIS)

    Yang, Jongmin; Hwang, Jinyul; Sung, Hyung Jin

    2016-01-01

    Highlights: • The structural organization of the quiescent core region in a turbulent channel flow is explored. • The quiescent core region is the uniform momentum zone located at the center of the channel. • The boundary of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. • The prograde and retrograde vortices form a counter-rotating vortex pair at the boundary of the core region. - Abstract: The structural organization of the quiescent core region in a turbulent channel flow was explored using direct numerical simulation data at Re_τ = 930. The quiescent core region is the uniform momentum zone located at the center of the channel, and contains the highest momentum with a low level of turbulence. The boundary of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. The streamwise velocity changes abruptly near the boundary of the core region. The abrupt jump leads the increase of the velocity gradient, which is similar to the vorticity thickness of the laminar superlayer at the turbulent/non-turbulent interface. The strong shear induced from the abrupt change is originated from the vortical structure lying on the boundary of the core region. The spanwise population densities of the prograde and retrograde vortices have a local maximum near the boundary of the core region. The prograde vortex dominantly contributes to the total mean shear near the core boundary and the contribution to the total mean shear rapidly decreases within the core region. The prograde and retrograde vortices form a counter-rotating vortex pair at the boundary of the core region associated with the nibbling mechanism. The boundary of the core region contains large-scale concave and convex features. The concave (convex) core interface is organized by the negative-u (positive-u) regions which induce the ejections (sweeps) around the core boundary.

  19. CFD Validation with a Multi-Block Experiment to Evaluate the Core Bypass Flow in VHTR

    International Nuclear Information System (INIS)

    Yoon, Su Jong; Lee, Jeong Hun; Park, Goon Cherl; Kim, Min Hwan

    2010-01-01

    Core bypass flow of Very High Temperature Reactor (VHTR) is defined as the ineffective coolant which passes through the bypass gaps between the block columns and the crossflow gaps between the stacked blocks. This flows lead to the variation of the flow distribution in the core and affect the core thermal margin and the safety of VHTR. Therefore, bypass flow should be investigated and quantified. However, it is not a simple question, because the flow path of VHTR core is very complex. In particular, since dimensions of the bypass gap and the crossflow gap are of the order of few millimeters, it is very difficult to measure and to analyze the flow field at those gaps. Seoul National University (SNU) multi-block experiment was carried out to evaluate the bypass flow distribution and the flow characteristics. The coolant flow rate through outlet of each block column was measured, but the local flow field was measured restrictively in the experiment. Instead, CFD analysis was carried out to investigate the local phenomena of the experiment. A commercial CFD code CFX-12 was validated by comparing the simulation results and the experimental data

  20. Characterization of the core poloidal flow at ASDEX Upgrade

    Science.gov (United States)

    Lebschy, Alexander

    2017-10-01

    An essential result from neoclassical (NC) theory is that the fluid poloidal rotation (upol) of the main ions is strongly damped by magnetic pumping and, therefore, expected to be small (theory has been found at both DIII-D and TCV. This is qualitatively consistent with the edge results from both Alcator C-Mod and ASDEX Upgrade (AUG). At AUG thanks to an upgrade of the core charge exchange recombination spectroscopy (CXRS) diagnostics, the core upol can be evaluated through the inboard-outboard asymmetry of the toroidal rotation with an accuracy of 0.5 - 1 km / s . This measurement also provides the missing ingredient to evaluate the core (E-> × B->) velocity (uE-> × B->) via the radial force balance equation. At AUG the core upol (0.35 × B-> determined from CXRS and the perpendicular velocity measured from turbulence propagation. The difference between these two quantities is the turbulent phase velocity. The gathered dataset indicates that the transition in the turbulence regime occurs after the saturation of the energy confinement time. The author thankfully acknowledges the financial support from the Helmholtz Association of German Research Centers through the Helmholtz Young Investigators Group program.

  1. Calculation of local flow conditions in the lower core of a PWR with code-Saturne

    International Nuclear Information System (INIS)

    Fournier, Y.

    2003-01-01

    In order to better understand the stresses to which fuel rods are subjected, we need to improve our knowledge of the fluid flow inside the core. A code specialized for calculations in tube bundles is used to calculate the flow inside the whole of the core, with a resolution at the assembly level. Still, it is necessary to obtain realistic entry conditions, and these depend on the flow in the downcomer and lower plenum. Also, the flow in the first stages of the core features 4 incoming jets per assembly, and requires a resolution much finer than that used for the whole core calculation. A series of calculations are thus run with our incompressible Navier-Stokes solver, Code-Saturne, using a classical Ranse turbulence model. The first calculations involve a detailed geometry, including part of the cold legs, downcomer, lower plenum, and lower core of a pressurized water reactor. The level of detail includes most obstacles below the core. The lower core plate, being pierced with close to 800 holes, cannot be realistically represented within a practical mesh size, so that a head loss model is used. The lower core itself requiring even more detail is also represented with head losses. We make full use of Code-Saturne's non conforming mesh possibilities to represent a complex geometry, being careful to retain a good mesh quality. Starting just under the lower core, the mesh is aligned with fuel rod assemblies, so that different types of assemblies can be represented through different head loss coefficients. These calculations yield steady-state or near steady-state results, which are compared to experimental data, and should be sufficient to yield realistic entry conditions for full core calculations at assembly width resolution, and beyond those mechanical strain calculations. We are also interested in more detailed flow conditions and fluctuations in the lower core area, so as to better quantify vibrational input. This requires a much higher resolution, which we limit

  2. Optimized surface-slab excited-state muffin-tin potential and surface core level shifts

    International Nuclear Information System (INIS)

    Rundgren, J.

    2003-01-01

    An optimized muffin-tin (MT) potential for surface slabs with preassigned surface core-level shifts (SCLS's) is presented. By using the MT radii as adjustable parameters the model is able to conserve the definition of the SCLS with respect to the bulk and concurrently to generate a potential that is continuous at the MT radii. The model is conceived for elastic electron scattering in a surface slab with exchange-correlation interaction described by the local density approximation. The model employs two data bases for the self-energy of the signal electron (after Hedin and Lundqvist or Sernelius). The potential model is discussed in detail with two surface structures Be(101-bar0), for which SCLS's are available, and Cu(111)p(2x2)Cs, in which the close-packed radii of the atoms are extremely different. It is considered plausible that tensor LEED based on an optimized MT potential can be used for determining SCLS's

  3. Development of a detailed core flow analysis code for prismatic fuel reactors

    International Nuclear Information System (INIS)

    Bennett, R.G.

    1990-01-01

    The development of a computer code for the analysis of the detailed flow of helium in prismatic fuel reactors is reported. The code, called BYPASS, solves, a finite difference control volume formulation of the compressible, steady state fluid flow in highly cross-connected flow paths typical of the Modular High-Temperature Gas Cooled Reactor (MHTGR). The discretization of the flow in a core region typically considers the main coolant flow paths, the bypass gap flow paths, and the crossflow connections between them. 16 refs., 5 figs

  4. Using subdivision surfaces and adaptive surface simplification algorithms for modeling chemical heterogeneities in geophysical flows

    Science.gov (United States)

    Schmalzl, JöRg; Loddoch, Alexander

    2003-09-01

    We present a new method for investigating the transport of an active chemical component in a convective flow. We apply a three-dimensional front tracking method using a triangular mesh. For the refinement of the mesh we use subdivision surfaces which have been developed over the last decade primarily in the field of computer graphics. We present two different subdivision schemes and discuss their applicability to problems related to fluid dynamics. For adaptive refinement we propose a weight function based on the length of triangle edge and the sum of the angles of the triangle formed with neighboring triangles. In order to remove excess triangles we apply an adaptive surface simplification method based on quadric error metrics. We test these schemes by advecting a blob of passive material in a steady state flow in which the total volume is well preserved over a long time. Since for time-dependent flows the number of triangles may increase exponentially in time we propose the use of a subdivision scheme with diffusive properties in order to remove the small scale features of the chemical field. By doing so we are able to follow the evolution of a heavy chemical component in a vigorously convecting field. This calculation is aimed at the fate of a heavy layer at the Earth's core-mantle boundary. Since the viscosity variation with temperature is of key importance we also present a calculation with a strongly temperature-dependent viscosity.

  5. Surface roughness influences on the behaviour of flow inside microchannels

    Science.gov (United States)

    Farias, M. H.; Castro, C. S.; Garcia, D. A.; Henrique, J. S.

    2018-03-01

    This work discusses influence of the surface roughness on the behavior of liquids flowing inside microchannels. By measuring the flow profile using the micro-PIV technique, the flow of water inside two rectangular microchannels of different wall roughness and in a circular smooth microchannel was studied. Comparisons were made among the experimental results, showing that a metrological approach concerning surface characteristics of microdevices is required to ensure reliability of the measurements for flow analyses in microfluidic processes.

  6. ASCOT-1, Thermohydraulics of Axisymmetric PWR Core with Homogeneous Flow During LOCA

    International Nuclear Information System (INIS)

    1978-01-01

    1 - Nature of the physical problem solved: ASCOT-1 is used to analyze the thermo-hydraulic behaviour in a PWR core during a loss-of-coolant accident. 2 - Method of solution: The core is assumed to be axisymmetric two-dimensional and the conservation laws are solved by the method of characteristics. For the temperature response of fuel in the annular regions into which the core is divided, the heat conduction equations are solved by an explicit method with averaged flow conditions. 3 - Restrictions on the complexity of the problem: Axisymmetric two-dimensional homogeneous flows

  7. Investigation on the Core Bypass Flow in a Very High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin

    2013-10-22

    Uncertainties associated with the core bypass flow are some of the key issues that directly influence the coolant mass flow distribution and magnitude, and thus the operational core temperature profiles, in the very high-temperature reactor (VHTR). Designers will attempt to configure the core geometry so the core cooling flow rate magnitude and distribution conform to the design values. The objective of this project is to study the bypass flow both experimentally and computationally. Researchers will develop experimental data using state-of-the-art particle image velocimetry in a small test facility. The team will attempt to obtain full field temperature distribution using racks of thermocouples. The experimental data are intended to benchmark computational fluid dynamics (CFD) codes by providing detailed information. These experimental data are urgently needed for validation of the CFD codes. The following are the project tasks: • Construct a small-scale bench-top experiment to resemble the bypass flow between the graphite blocks, varying parameters to address their impact on bypass flow. Wall roughness of the graphite block walls, spacing between the blocks, and temperature of the blocks are some of the parameters to be tested. • Perform CFD to evaluate pre- and post-test calculations and turbulence models, including sensitivity studies to achieve high accuracy. • Develop the state-of-the art large eddy simulation (LES) using appropriate subgrid modeling. • Develop models to be used in systems thermal hydraulics codes to account and estimate the bypass flows. These computer programs include, among others, RELAP3D, MELCOR, GAMMA, and GAS-NET. Actual core bypass flow rate may vary considerably from the design value. Although the uncertainty of the bypass flow rate is not known, some sources have stated that the bypass flow rates in the Fort St. Vrain reactor were between 8 and 25 percent of the total reactor mass flow rate. If bypass flow rates are on the

  8. Study and analysis on the flow induced vibration of the core barrel of PWR

    International Nuclear Information System (INIS)

    Yao Weida; Shi Guolin; Jiang Nanyan; Peng YongYong; Zhang Huijun; Wang Yufen; Xie Yongcheng; Guo Chunhua; Shen Qinping

    1989-01-01

    The deduction of the resemblance criterion and the design of the test model by applying flow-solid coupling theory are described. The model analysis of a core barrel both in the air and stationary water were performed in a 1:10 model, thus obtaining the dynamic characteristic. In a 1:5 reactor model with a hydraulic closed loop, the inner structure and support were modeled for performing hydraulic closed loop, the inner structure and support were modeled for performing hydraulic vibration test of the core barrel. The flow induced pulse pressure of the core barrel and corresponding response were obtained by using miniature pressure capsule, strain gauge and accelerometer. Power spectrum, correlation functions, transfer function and amplitudes under different flow velocities were calculated. The hydraulic vibration test shows that the core barrel will be in safety during its 30-year life time

  9. Viscous flows stretching and shrinking of surfaces

    CERN Document Server

    Mehmood, Ahmer

    2017-01-01

    This authored monograph provides a detailed discussion of the boundary layer flow due to a moving plate. The topical focus lies on the 2- and 3-dimensional case, considering axially symmetric and unsteady flows. The author derives a criterion for the self-similar and non-similar flow, and the turbulent flow due to a stretching or shrinking sheet is also discussed. The target audience primarily comprises research experts in the field of boundary layer flow, but the book will also be beneficial for graduate students.

  10. Deconvolution-based resolution enhancement of chemical ice core records obtained by continuous flow analysis

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Andersen, Katrine K.; Johnsen, Sigfus Johann

    2005-01-01

    Continuous flow analysis (CFA) has become a popular measuring technique for obtaining high-resolution chemical ice core records due to an attractive combination of measuring speed and resolution. However, when analyzing the deeper sections of ice cores or cores from low-accumulation areas...... of the data for high-resolution studies such as annual layer counting. The presented method uses deconvolution techniques and is robust to the presence of noise in the measurements. If integrated into the data processing, it requires no additional data collection. The method is applied to selected ice core...

  11. Surface flow in severe plastic deformation of metals by sliding

    International Nuclear Information System (INIS)

    Mahato, A; Yeung, H; Chandrasekar, S; Guo, Y

    2014-01-01

    An in situ study of flow in severe plastic deformation (SPD) of surfaces by sliding is described. The model system – a hard wedge sliding against a metal surface – is representative of surface conditioning processes typical of manufacturing, and sliding wear. By combining high speed imaging and image analysis, important characteristics of unconstrained plastic flow inherent to this system are highlighted. These characteristics include development of large plastic strains on the surface and in the subsurface by laminar type flow, unusual fluid-like flow with vortex formation and surface folding, and defect and particle generation. Preferred conditions, as well as undesirable regimes, for surface SPD are demarcated. Implications for surface conditioning in manufacturing, modeling of surface deformation and wear are discussed

  12. Calculation of pressure drop and flow redistribution in the LMFBR core

    International Nuclear Information System (INIS)

    Morgado, O.J.

    1984-01-01

    The flow redistribution through fuel assemblies of LMFBRs: for the correct calculation of mass flow rates and pressure drop, are studied. Using a quasi-static formulation of conservation equations of mass and energy, a computer program was developed to simulate any arbitrary number of flow channels, operating at different linear power levels. Therefore f flow channels, operating at different linear power levels. Therefore, it was possible to perform thermal transient calculations for the Clinch River reactor core. The results of the calculations agree with the data found in the literature and supply accurate information about flow redistribution, average temperature, and pressure drop in the core, when the reactor is operated at conditions from the designed flow conditions, as is always the case in a load changing operation, or during transients. (Autor) [pt

  13. A parallel solution-adaptive scheme for predicting multi-phase core flows in solid propellant rocket motors

    International Nuclear Information System (INIS)

    Sachdev, J.S.; Groth, C.P.T.; Gottlieb, J.J.

    2003-01-01

    The development of a parallel adaptive mesh refinement (AMR) scheme is described for solving the governing equations for multi-phase (gas-particle) core flows in solid propellant rocket motors (SRM). An Eulerian formulation is used to described the coupled motion between the gas and particle phases. A cell-centred upwind finite-volume discretization and the use of limited solution reconstruction, Riemann solver based flux functions for the gas and particle phases, and explicit multi-stage time-stepping allows for high solution accuracy and computational robustness. A Riemann problem is formulated for prescribing boundary data at the burning surface. Efficient and scalable parallel implementations are achieved with domain decomposition on distributed memory multiprocessor architectures. Numerical results are described to demonstrate the capabilities of the approach for predicting SRM core flows. (author)

  14. Calculation of the flow distribution for the new core of the RA-6 reactor

    International Nuclear Information System (INIS)

    Garcia, J.C.; Delmastro, Dario F.

    2007-01-01

    In this work the pressure drop, the flow distribution, effective cooling flow rate and the velocity in the subchannels that cool fuel plates for the new core of RA-6 research reactor were calculated. These calculations were performed for a flow of 340 m 3 /hr and water temperatures of 12 C degrees, of 35 C degrees and 42 C degrees. The flow distribution was calculated without considering either safety factors or geometric changes. All the calculations were performed considering the flow as isothermal. (author) [es

  15. New advection schemes for free surface flows

    International Nuclear Information System (INIS)

    Pavan, Sara

    2016-01-01

    The purpose of this thesis is to build higher order and less diffusive schemes for pollutant transport in shallow water flows or 3D free surface flows. We want robust schemes which respect the main mathematical properties of the advection equation with relatively low numerical diffusion and apply them to environmental industrial applications. Two techniques are tested in this work: a classical finite volume method and a residual distribution technique combined with a finite element method. For both methods we propose a decoupled approach since it is the most advantageous in terms of accuracy and CPU time. Concerning the first technique, a vertex-centred finite volume method is used to solve the augmented shallow water system where the numerical flux is computed through an Harten-Lax-Van Leer-Contact Riemann solver. Starting from this solution, a decoupled approach is formulated and is preferred since it allows to compute with a larger time step the advection of a tracer. This idea was inspired by Audusse, E. and Bristeau, M.O. [13]. The Monotonic Upwind Scheme for Conservation Law, combined with the decoupled approach, is then used for the second order extension in space. The wetting and drying problem is also analysed and a possible solution is presented. In the second case, the shallow water system is entirely solved using the finite element technique and the residual distribution method is applied to the solution of the tracer equation, focusing on the case of time-dependent problems. However, for consistency reasons the resolution of the continuity equation must be considered in the numerical discretization of the tracer. In order to get second order schemes for unsteady cases a predictor-corrector scheme is used in this work. A first order but less diffusive version of the predictor-corrector scheme is also introduced. Moreover, we also present a new locally semi-implicit version of the residual distribution method which, in addition to good properties in

  16. Computational fluid dynamic analysis of core bypass flow phenomena in a prismatic VHTR

    International Nuclear Information System (INIS)

    Sato, Hiroyuki; Johnson, Richard; Schultz, Richard

    2010-01-01

    The core bypass flow in a prismatic very high temperature reactor (VHTR) is an important design consideration and can have considerable impact on the condition of reactor core internals including fuels. The interstitial gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The occurrence of hot spots in the core and lower plenum and hot streaking in the lower plenum (regions of very hot gas flow) are affected by bypass flow. In the present study, three-dimensional computational fluid dynamic (CFD) calculations of a typical prismatic VHTR are conducted to better understand bypass flow phenomena and establish an evaluation method for the reactor core using the commercial CFD code FLUENT. Parametric calculations changing several factors in a one-twelfth sector of a fuel column are performed. The simulations show the impact of each factor on bypass flow and the resulting flow and temperature distributions in the prismatic core. Factors include inter-column gap-width, turbulence model, axial heat generation profile and geometry change from irradiation-induced shrinkage in the graphite block region. It is shown that bypass flow provides a significant cooling effect on the prismatic block and that the maximum fuel and coolant channel outlet temperatures increase with an increase in gap-width, especially when a peak radial factor is applied to the total heat generation rate. Also, the presence of bypass flow causes a large lateral temperature gradient in the block and also dramatically increases the variation in coolant channel outlet temperatures for a given block that may have repercussions on the structural integrity of the graphite, the neutronics and the potential for hot streaking and hot spots occurring in the lower plenum.

  17. A Level Set Discontinuous Galerkin Method for Free Surface Flows

    DEFF Research Database (Denmark)

    Grooss, Jesper; Hesthaven, Jan

    2006-01-01

    We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by embedding and represented by a levelset. We discuss the discretization of the flow equations and the level set equation...

  18. Local grid refinement for free-surface flow simulations

    NARCIS (Netherlands)

    van der Plas, Peter

    2017-01-01

    The principal goal of the current study is to explore and investigate the potential of local grid refinement for increasing the numerical efficiency of free-surface flow simulations in a practical context. In this thesis we propose a method for local grid refinement in the free-surface flow model

  19. Transient disturbance growth in flows over convex surfaces

    Science.gov (United States)

    Karp, Michael; Hack, M. J. Philipp

    2017-11-01

    Flows over curved surfaces occur in a wide range of applications including airfoils, compressor and turbine vanes as well as aerial, naval and ground vehicles. In most of these applications the surface has convex curvature, while concave surfaces are less common. Since monotonic boundary-layer flows over convex surfaces are exponentially stable, they have received considerably less attention than flows over concave walls which are destabilized by centrifugal forces. Non-modal mechanisms may nonetheless enable significant disturbance growth which can make the flow susceptible to secondary instabilities. A parametric investigation of the transient growth and secondary instability of flows over convex surfaces is performed. The specific conditions yielding the maximal transient growth and strongest instability are identified. The effect of wall-normal and spanwise inflection points on the instability process is discussed. Finally, the role and significance of additional parameters, such as the geometry and pressure gradient, is analyzed.

  20. Influence of slip-surface geometry on earth-flow deformation, Montaguto earth flow, southern Italy

    Science.gov (United States)

    Guerriero, L.; Coe, Jeffrey A.; Revellio, P.; Grelle, G.; Pinto, F.; Guadagno, F.

    2016-01-01

    We investigated relations between slip-surface geometry and deformational structures and hydrologic features at the Montaguto earth flow in southern Italy between 1954 and 2010. We used 25 boreholes, 15 static cone-penetration tests, and 22 shallow-seismic profiles to define the geometry of basal- and lateral-slip surfaces; and 9 multitemporal maps to quantify the spatial and temporal distribution of normal faults, thrust faults, back-tilted surfaces, strike-slip faults, flank ridges, folds, ponds, and springs. We infer that the slip surface is a repeating series of steeply sloping surfaces (risers) and gently sloping surfaces (treads). Stretching of earth-flow material created normal faults at risers, and shortening of earth-flow material created thrust faults, back-tilted surfaces, and ponds at treads. Individual pairs of risers and treads formed quasi-discrete kinematic zones within the earth flow that operated in unison to transmit pulses of sediment along the length of the flow. The locations of strike-slip faults, flank ridges, and folds were not controlled by basal-slip surface topography but were instead dependent on earth-flow volume and lateral changes in the direction of the earth-flow travel path. The earth-flow travel path was strongly influenced by inactive earth-flow deposits and pre-earth-flow drainages whose positions were determined by tectonic structures. The implications of our results that may be applicable to other earth flows are that structures with strikes normal to the direction of earth-flow motion (e.g., normal faults and thrust faults) can be used as a guide to the geometry of basal-slip surfaces, but that depths to the slip surface (i.e., the thickness of an earth flow) will vary as sediment pulses are transmitted through a flow.

  1. Liquid flow along a solid surface reversibly alters interfacial chemistry.

    Science.gov (United States)

    Lis, Dan; Backus, Ellen H G; Hunger, Johannes; Parekh, Sapun H; Bonn, Mischa

    2014-06-06

    In nature, aqueous solutions often move collectively along solid surfaces (for example, raindrops falling on the ground and rivers flowing through riverbeds). However, the influence of such motion on water-surface interfacial chemistry is unclear. In this work, we combine surface-specific sum frequency generation spectroscopy and microfluidics to show that at immersed calcium fluoride and fused silica surfaces, flow leads to a reversible modification of the surface charge and subsequent realignment of the interfacial water molecules. Obtaining equivalent effects under static conditions requires a substantial change in bulk solution pH (up to 2 pH units), demonstrating the coupling between flow and chemistry. These marked flow-induced variations in interfacial chemistry should substantially affect our understanding and modeling of chemical processes at immersed surfaces. Copyright © 2014, American Association for the Advancement of Science.

  2. CFD analysis of the effect of rolling motion on the flow distribution at the core inlet

    International Nuclear Information System (INIS)

    Yan, B.H.; Zhang, G.; Gu, H.Y.

    2012-01-01

    Highlights: ► The flow distribution at the core inlet in rolling motion is investigated. ► In rolling motion, the variation of flow distribution factor is not regular. ► The minimum flow distribution factor could be decreased by rolling motion. ► The effect of rolling motion diminishes with Reynolds number increasing. ► Effect of rolling motion in single loop operation is more significant. - Abstract: The flow distribution at the core inlet in rolling motion is investigated with software CFX12.0. The calculation results were in agreement with experimental data in steady state. As the increasing of rolling amplitude and the decreasing of rolling period, the effect of rolling motion on the flow distribution factor and the flowing behavior increases. In rolling motion, the variation of flow distribution factor is not regular. The rolling motion could decrease the minimum flow distribution factor. The effect of rolling motion on the coolant field and flow distribution diminishes with the Reynolds number increasing. The effect of rolling motion on the flow distribution in the case of single loop operation is more significant than that in the case of double loops operation.

  3. CoreFlow: A computational platform for integration, analysis and modeling of complex biological data

    DEFF Research Database (Denmark)

    Pasculescu, Adrian; Schoof, Erwin; Creixell, Pau

    2014-01-01

    between data generation, analysis and manuscript writing. CoreFlow is being released to the scientific community as an open-sourced software package complete with proteomics-specific examples, which include corrections for incomplete isotopic labeling of peptides (SILAC) or arginine-to-proline conversion......A major challenge in mass spectrometry and other large-scale applications is how to handle, integrate, and model the data that is produced. Given the speed at which technology advances and the need to keep pace with biological experiments, we designed a computational platform, CoreFlow, which...... provides programmers with a framework to manage data in real-time. It allows users to upload data into a relational database (MySQL), and to create custom scripts in high-level languages such as R, Python, or Perl for processing, correcting and modeling this data. CoreFlow organizes these scripts...

  4. Calculation of pressure drop and flow redistribution in the core of LMFBR type reactors

    International Nuclear Information System (INIS)

    Botelho, D.A.; Morgado, O.J.

    1985-01-01

    It is studied the flow redistribution through of fuel elements to the pressure drop calculation in the core of sodium cooled reactors. Using the quasi-static formulation of equations of the conservation of mass, energy and momentum, it was developed a computer program to flow redistribution calculations and pressure drop for different power levels and total flow simulating an arbitrary number of channels for sodium flowing . An optimization of the number of sufficient channels for calculations of this nature is done. The method is applied in studies of transients in the same reactor. (M.C.K.) [pt

  5. Flow with boiling in four-cusp channels simulating damaged core in PWR type reactors

    International Nuclear Information System (INIS)

    Esteves, M.M.

    1985-01-01

    The study of subcooled nucleate flow boiling in non-circular channels is of great importance to engineering applications in particular to Nuclear Engineering. In the present work, an experimental apparatus, consisting basically of a refrigeration system, running on refrigerant-12, has been developed. Preliminary tests were made with a circular tube. The main objective has been to analyse subcooled flow boiling in four-cusp channels simulating the flow conditions in a PWR core degraded by accident. Correlations were developed for the forced convection film coefficient for both single-phase and subcooled flow boiling. The incipience of boiling in such geometry has also been studied. (author) [pt

  6. Ice-sheet flow conditions deduced from mechanical tests of ice core

    DEFF Research Database (Denmark)

    Miyamoto, Atsushi; Narita, Hideki; Hondoh, Takeo

    1999-01-01

    Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate....... It was revealed that cloudy bands affect ice-deformation processes, but the details remain unclear. Udgivelsesdato: June......Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate......-core samples with basal planes parallel to the horizontal plane of the ice sheet. The ice-flow enhancement factors show a gradual increase with depth down to approximately 2000 m. These results can be interpreted in terms of an increase in the fourth-order Schmid factor. Below 2000 m depth, the flow...

  7. Investigation of Abnormal Heat Transfer and Flow in a VHTR Reactor Core

    Energy Technology Data Exchange (ETDEWEB)

    Kawaji, Masahiro [City College of New York, NY (United States); Valentin, Francisco I. [City College of New York, NY (United States); Artoun, Narbeh [City College of New York, NY (United States); Banerjee, Sanjoy [City College of New York, NY (United States); Sohal, Manohar [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schultz, Richard [Idaho National Lab. (INL), Idaho Falls, ID (United States); McEligot, Donald M. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-12-21

    The main objective of this project was to identify and characterize the conditions under which abnormal heat transfer phenomena would occur in a Very High Temperature Reactor (VHTR) with a prismatic core. High pressure/high temperature experiments have been conducted to obtain data that could be used for validation of VHTR design and safety analysis codes. The focus of these experiments was on the generation of benchmark data for design and off-design heat transfer for forced, mixed and natural circulation in a VHTR core. In particular, a flow laminarization phenomenon was intensely investigated since it could give rise to hot spots in the VHTR core.

  8. Investigation of Abnormal Heat Transfer and Flow in a VHTR Reactor Core

    International Nuclear Information System (INIS)

    Kawaji, Masahiro; Valentin, Francisco I.; Artoun, Narbeh; Banerjee, Sanjoy; Sohal, Manohar; Schultz, Richard; McEligot, Donald M.

    2015-01-01

    The main objective of this project was to identify and characterize the conditions under which abnormal heat transfer phenomena would occur in a Very High Temperature Reactor (VHTR) with a prismatic core. High pressure/high temperature experiments have been conducted to obtain data that could be used for validation of VHTR design and safety analysis codes. The focus of these experiments was on the generation of benchmark data for design and off-design heat transfer for forced, mixed and natural circulation in a VHTR core. In particular, a flow laminarization phenomenon was intensely investigated since it could give rise to hot spots in the VHTR core.

  9. 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.

  10. Effect of a Central Graphite Column on a Pebble Flow in a Pebble Bed Core

    International Nuclear Information System (INIS)

    In, W. K.; Lee, W. J.; Chang, J. H.

    2006-01-01

    A pebble bed reactor(PBR) uses coated fuel particles embedded in spherical graphite fuel pebbles. The fuel pebbles flow down through the core during an operation. The pebble bed core is configured as cylindrical or annular depending on the reactor power. It is well known that an annular core can increase a cores' thermal power. The annular inner core zone is typically filled with movable graphite balls or a fixed graphite column. The first problem with this conventional annular core is that it is difficult to maintain a boundary between the central graphite ball zone and the outer fuel zone. The second problem is that it is expensive to replace the central fixed graphite column after several tens of years of reactor operation. In order to resolve these problems, a PBR with a central graphite column in a low core is invented. This paper presents the effect of the central graphite column on a pebble flow by using the computational fluid dynamics(CFD) code, CFX-10

  11. On the computation of the turbulent flow near rough surface

    Science.gov (United States)

    Matveev, S. K.; Jaychibekov, N. Zh.; Shalabayeva, B. S.

    2018-05-01

    One of the problems in constructing mathematical models of turbulence is a description of the flows near a rough surface. An experimental study of such flows is also difficult because of the impossibility of measuring "inside" the roughness. The theoretical calculation is difficult because of the lack of equations describing the flow in this zone. In this paper, a new turbulence model based on the differential equation of turbulent viscosity balance was used to describe a turbulent flow near a rough surface. The difference between the new turbulence model and the previously known consists in the choice of constants and functions that determine the generation, dissipation and diffusion of viscosity.

  12. 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.)

  13. Effects of graphite surface roughness on bypass flow computations for an HTGR

    Energy Technology Data Exchange (ETDEWEB)

    Tung, Yu-Hsin, E-mail: touushin@gmail.com [Idaho National Laboratory, P.O. Box 1625, M.S. 3855, Idaho Falls, ID (United States); Johnson, Richard W., E-mail: Rich.Johnson@inl.gov [Idaho National Laboratory, P.O. Box 1625, M.S. 3855, Idaho Falls, ID (United States); Sato, Hiroyuki, E-mail: sato.hiroyuki09@jaea.go.jp [Idaho National Laboratory, P.O. Box 1625, M.S. 3855, Idaho Falls, ID (United States)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer CFD calculations are made of bypass flow between graphite blocks in HTGR. Black-Right-Pointing-Pointer Several turbulence models are employed to compare to friction and heat transfer correlations. Black-Right-Pointing-Pointer Parameters varied include bypass gap width and surface roughness. Black-Right-Pointing-Pointer Surface roughness causes increases in max fuel and coolant temperatures. Black-Right-Pointing-Pointer Surface roughness does not cause increase in outlet coolant temperature variation. - Abstract: Bypass flow in a prismatic high temperature gas reactor (HTGR) occurs between graphite blocks as they sit side by side in the core. Bypass flow is not intentionally designed to occur in the reactor, but is present because of tolerances in manufacture, imperfect installation and expansion and shrinkage of the blocks from heating and irradiation. It is desired to increase the knowledge of the effects of such flow; it has been suggested that it may be as much as 20% of the total helium coolant flow [INL Report 2007, INL/EXT-07-13289]. Computational fluid dynamic (CFD) simulations can provide estimates of the scale and impacts of bypass flow. Previous CFD calculations have examined the effects of bypass gap width, level and distribution of heat generation and effects of shrinkage. The present contribution examines the effects of graphite surface roughness on the bypass flow for different relative roughness factors for three gap widths. Such calculations should be validated using specific bypass flow measurements. While such experiments are currently underway for the specific reference prismatic HTGR design for the next generation nuclear plant (NGNP) program of the U.S. Dept. of Energy, the data are not yet available. To enhance confidence in the present calculations, wall shear stress and heat transfer results for several turbulence models and their associated wall treatments are first compared for steady flow in a

  14. Development of a detailed core flow analysis code for prismatic fuel reactors

    International Nuclear Information System (INIS)

    Bennett, R.G.

    1990-01-01

    The detailed analysis of the core flow distribution in prismatic fuel reactors is of interest for modular high-temperature gas-cooled reactor (MHTGR) design and safety analyses. Such analyses involve the steady-state flow of helium through highly cross-connected flow paths in and around the prismatic fuel elements. Several computer codes have been developed for this purpose. However, since they are proprietary codes, they are not generally available for independent MHTGR design confirmation. The previously developed codes do not consider the exchange or diversion of flow between individual bypass gaps with much detail. Such a capability could be important in the analysis of potential fuel block motion, such as occurred in the Fort St. Vrain reactor, or for the analysis of the conditions around a flow blockage or misloaded fuel block. This work develops a computer code with fairly general-purpose capabilities for modeling the flow in regions of prismatic fuel cores. The code, called BYPASS solves a finite difference control volume formulation of the compressible, steady-state fluid flow in highly cross-connected flow paths typical of the MHTGR

  15. Study of core flow distribution for small modular natural circulation lead or lead-alloy cooled fast reactors

    International Nuclear Information System (INIS)

    Chen, Zhao; Zhao, Pengcheng; Zhou, Guangming; Chen, Hongli

    2014-01-01

    Highlights: • A core flow distribution calculation code for natural circulation LFRs was developed. • The comparison study between the channel method and the CFD method was conducted. • The core flow distribution analysis and optimization design for a 10MW natural circulation LFR was conducted. - Abstract: Small modular natural circulation lead or lead-alloy cooled fast reactor (LFR) is a potential candidate for LFR development. It has many attractive advantages such as reduced capital costs and inherent safety. The core flow distribution calculation is an important issue for nuclear reactor design, which will provide important input parameters to thermal-hydraulic analysis and safety analysis. The core flow distribution calculation of a natural circulation LFR is different from that of a forced circulation reactor. In a forced circulation reactor, the core flow distribution can be controlled and adjusted by the pump power and the flow distributor, while in a natural circulation reactor, the core flow distribution is automatically adjusted according to the relationship between the local power and the local resistance feature. In this paper, a non-uniform heated parallel channel flow distribution calculation code was developed and the comparison study between the channel method and the CFD method was carried out to assess the exactness of the developed code. The core flow distribution analysis and optimization design for a 10MW natural circulation LFR was conducted using the developed code. A core flow distribution optimization design scheme for a 10MW natural circulation LFR was proposed according to the optimization analysis results

  16. Integral manifolding structure for fuel cell core having parallel gas flow

    Science.gov (United States)

    Herceg, Joseph E.

    1984-01-01

    Disclosed herein are manifolding means for directing the fuel and oxidant gases to parallel flow passageways in a fuel cell core. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte and interconnect wall consists respectively of anode and cathode materials layered on the opposite sides of electrolyte material, or on the opposite sides of interconnect material. A core wall projects beyond the open ends of the defined core passageways and is disposed approximately midway between and parallel to the adjacent overlaying and underlying interconnect walls to define manifold chambers therebetween on opposite sides of the wall. Each electrolyte wall defining the flow passageways is shaped to blend into and be connected to this wall in order to redirect the corresponding fuel and oxidant passageways to the respective manifold chambers either above or below this intermediate wall. Inlet and outlet connections are made to these separate manifold chambers respectively, for carrying the fuel and oxidant gases to the core, and for carrying their reaction products away from the core.

  17. CoreFlow: Enriching Bro security events using network traffic monitoring data

    NARCIS (Netherlands)

    Koning, R.; Buraglio, N.; de Laat, C.; Grosso, P.

    Attacks against network infrastructures can be detected by Intrusion Detection Systems (IDS). Still reaction to these events are often limited by the lack of larger contextual information in which they occurred. In this paper we present CoreFlow, a framework for the correlation and enrichment of IDS

  18. Simulant-material experimental investigation of flow dynamics in the CRBR Upper-Core Structure

    International Nuclear Information System (INIS)

    Wilhelm, D.; Starkovich, V.S.; Chapyak, E.J.

    1982-09-01

    The results of a simulant-material experimental investigation of flow dynamics in the Clinch River Breeder Reactor (CRBR) Upper Core Structure are described. The methodology used to design the experimental apparatus and select test conditions is detailed. Numerous comparisons between experimental data and SIMMER-II Code calculations are presented with both advantages and limitations of the SIMMER modeling features identified

  19. Core dynamics analysis for reactivity insertion and loss of coolant flow tests using the HTTR

    International Nuclear Information System (INIS)

    Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Takeda, Tetsuaki

    2007-01-01

    The High Temperature engineering Test Reactor (HTTR) is a graphite-moderated and a gas-cooled reactor with a thermal power of 30 MW and a reactor outlet coolant temperature of 950degC (SAITO, 1994). Safety demonstration tests using the HTTR are in progress to verify its inherent safety features and improve the safety technology and design methodology for High-Temperature Gas-cooled Reactors (HTGRs) (TACHIBANA 2002) (NAKAGAWA 2004). The reactivity insertion test is one of the safety demonstration tests for the HTTR. This test simulates the rapid increase in the reactor power by withdrawing the control rod without operating the reactor power control system. In addition, the loss of coolant flow tests has been conducted to simulate the rapid decrease in the reactor power by tripping one, two or all out of three gas circulators. The experimental results have revealed the inherent safety features of HTGRs, such as the negative reactivity feedback effect. The numerical analysis code, which was named ACCORD (TAKAMATSU 2006), was developed to analyze the reactor dynamics including the flow behavior in the HTTR core. We used a conventional method, namely, a one-dimensional flow channel model and reactor kinetics model with a single temperature coefficient, taking into account the temperature changes in the core. However, a slight difference between the analytical and experimental results was observed. Therefore, we have modified this code to use a model with four parallel channels and twenty temperature coefficients in the core. Furthermore, we added another analytical model of the core for calculating the heat conduction between the fuel channels and the core in the case of the loss of coolant flow tests. This paper describes the validation results for the newly developed code using the experimental results of the reactivity insertion test as well as the loss of coolant flow tests by tripping one or two out of three gas circulators. Finally, the pre-analytical result of

  20. Solid oxide fuel cell having monolithic cross flow core and manifolding

    International Nuclear Information System (INIS)

    Poeppel, R.B.; Dusek, J.T.

    1984-01-01

    This invention discloses a monolithic core construction having the flow passageways for the fuel and for the oxidant gases extended transverse to one another, whereby full face core manifolding can be achieved for these gases and their reaction products. The core construction provides that only anode material surround each fuel passageway and only cathode material surround each oxidant passageway, each anode and each cathode further sandwiching at spaced opposing sides electrolyte and interconnect materials to define electrolyte and interconnect walls. Webs of the cathode and anode material hold the electrolyte and interconnect walls spaced apart to define the flow passages. The composite anode and cathode wall structures are further alternately stacked on one another (with the separating electrolyte or interconnect material typically being a single common layer) whereby the fuel passageway and the oxidant passageways are disposed transverse to one another

  1. Applying CLSM to increment core surfaces for histometric analyses: A novel advance in quantitative wood anatomy

    OpenAIRE

    Wei Liang; Ingo Heinrich; Gerhard Helle; I. Dorado Liñán; T. Heinken

    2013-01-01

    A novel procedure has been developed to conduct cell structure measurements on increment core samples of conifers. The procedure combines readily available hardware and software equipment. The essential part of the procedure is the application of a confocal laser scanning microscope (CLSM) which captures images directly from increment cores surfaced with the advanced WSL core-microtome. Cell wall and lumen are displayed with a strong contrast due to the monochrome black and green nature of th...

  2. Flow Structure and Surface Topology on a UCAV Planform

    Science.gov (United States)

    Elkhoury, Michel; Yavuz, Metin; Rockwell, Donald

    2003-11-01

    Flow past a X-45 UCAV planform involves the complex generation and interaction of vortices, their breakdown and occurrence of surface separation and stall. A cinema technique of high-image-density particle image velocimetry, in conjunction with dye visualization, allows characterization of the time-averaged and instantaneous states of the flow, in terms of critical points of the near-surface streamlines. These features are related to patterns of surface normal vorticity and velocity fluctuation. Spectral analysis of the naturally occurring unsteadiness of the flow allows definition of the most effective frequencies for small-amplitude perturbation of the wing, which leads to substantial alterations of the aforementioned patterns of flow structure and topology adjacent to the surface.

  3. Measurement of two-phase flow at the core upper plenum interface under simulated reflood conditions

    International Nuclear Information System (INIS)

    Thomas, D.G.; Combs, S.K.; Bagwell, M.E.

    1980-01-01

    Objectives of the Instrument Development Loop program were to simulate flows at the core/upper plenum interface during the reflood phase of a LOCA and to develop instruments for measuring mass-flows at this interface. A tie plate drag body was developed and tested successfully, and the data obtained were shown to be equivalent to pressure drops. The tie-plate drag body gave useful measurements in pure downflow, and the drag/turbine combination correlates with mass flow for high upflow

  4. Flowing and freezing of molten core materials during unprotected loss of flow accidents in sodium cooled fast reactors

    International Nuclear Information System (INIS)

    Maschek, W.; Royl, P.

    1988-09-01

    Flowing and freezing of mobile core materials change the fissile material distribution and core-inventory under hypothetical accident conditions and determine the path to permanent shutdown of the neutronic events and the energetic potentials. The report classifies the bondary conditions for such flowing and freezing processes by going through the different situations under which these processes can occur in the scenario of the unprotected loss of flow (ULOF) accident. The classification is based on ULOF-accident simulations for a homogeneous reactor core concept of a 300 MWe LMFBR (e. g. SNR-300), but many boundary conditions are also characteristic for other core designs. A review of the relevant experiments is then made to correlate the available experimental information with these classified boundary conditions and to look at the resulting flowing and freezing processes. Boundary conditions that have been experimentally shown to be important are assigned high priorities. The data are specifically valued in relation to these boundary conditions of high priorities. The review includes the major experimental programs with published results. The discussion shows that the results from most clean condition tests for melt relocations are valuable for a better understanding of basic phenomena and analytical model development, but are not directly applicable to real accident conditions. The database for relevant boundary conditions from the ULOF scenario is limited and largely included in integral sequence tests from which quantitative information for modelling is difficult to obtain. Needs for additional investigations are identified. The suggestions are mainly restricted to investigations of the early phase of fuel removal. They are given with reference to candidate facilities and include relocations in the subassemblies and in the inter-subassembly gaps. Particular emphasis is put on the leading edge properties and possible driving forces to which more attention

  5. Free-surface viscous flow solution methods for ship hydrodynamics

    NARCIS (Netherlands)

    Wackers, J.; Koren, B.; Raven, H.C.; Ploeg, van der A.; Starke, A.R.; Deng, G.; Queutey, P.; Visonneau, M.; Hino, T.; Ohashi, K.

    2011-01-01

    The simulation of viscous free-surface water flow is a subject that has reached a certain maturity and is nowadays used in industrial applications, like the simulation of the flow around ships. While almost all methods used are based on the Navier-Stokes equations, the discretisation methods for the

  6. Deep layer-resolved core-level shifts in the beryllium surface

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    Core-level energy shifts for the beryllium surface region are calculated by means of a Green’s function technique within the tight-binding linear muffin-tin orbitals method. Both initial- and final-state effects in the core-ionization process are fully accounted for. Anomalously large energy shifts...

  7. 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)

  8. Numerical study on coolant flow distribution at the core inlet for an integral pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lin; Peng, Min Jun; Xia, Genglei; Lv, Xing; Li, Ren [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin (China)

    2017-02-15

    When an integral pressurized water reactor is operated under low power conditions, once-through steam generator group operation strategy is applied. However, group operation strategy will cause nonuniform coolant flow distribution at the core inlet and lower plenum. To help coolant flow mix more uniformly, a flow mixing chamber (FMC) has been designed. In this paper, computational fluid dynamics methods have been used to investigate the coolant distribution by the effect of FMC. Velocity and temperature characteristics under different low power conditions and optimized FMC configuration have been analyzed. The results illustrate that the FMC can help improve the nonuniform coolant temperature distribution at the core inlet effectively; at the same time, the FMC will induce more resistance in the downcomer and lower plenum.

  9. Direct numerical simulations of reacting flows with detailed chemistry using many-core/GPU acceleration

    KAUST Repository

    Herná ndez Pé rez, Francisco E.; Mukhadiyev, Nurzhan; Xu, Xiao; Sow, Aliou; Lee, Bok Jik; Sankaran, Ramanan; Im, Hong G.

    2018-01-01

    A new direct numerical simulation (DNS) code for multi-component gaseous reacting flows has been developed at KAUST, with the state-of-the-art programming model for next generation high performance computing platforms. The code, named KAUST Adaptive Reacting Flows Solver (KARFS), employs the MPI+X programming, and relies on Kokkos for “X” for performance portability to multi-core, many-core and GPUs, providing innovative software development while maintaining backward compatibility with established parallel models and legacy code. The capability and potential of KARFS to perform DNS of reacting flows with large, detailed reaction mechanisms is demonstrated with various model problems involving ignition and turbulent flame propagations with varying degrees of chemical complexities.

  10. Fundamental study on flow characteristics of disrupted core pool at a low energy level (Joint research)

    International Nuclear Information System (INIS)

    Morita, Koji; Liu, Ping; Matsumoto, Tatsuya; Fukuda, Kenji; Tobita, Yoshiharu; Yamano, Hidemasa; Sato, Ikken

    2009-09-01

    Dynamic behaviors of solid-particle dominant multiphase flows were investigated to model the mobility of core materials in a low-energy disrupted core of a liquid metal fast reactor. Two series of experiments were performed, those were dam-break experiments and bubble visualization experiments. Verification of fluid-dynamics models used in the fast reactor safety analysis code SIMMER-III was also conducted based on the numerical simulations of these experiments. The experimental analyses show that SIMMER-III can represent effects of solid particle interaction on multiphase flow behaviors by adjusting model parameters of the particle jamming model if the particles are immersed in liquid phase. Further improvement of SIMMER-III with more generalized models is necessary to appropriately simulate interactions between solid particles in a wider range of flow conditions. (author)

  11. Flow velocity calculation to avoid instability in a typical research reactor core

    International Nuclear Information System (INIS)

    Oliveira, Carlos Alberto de; Mattar Neto, Miguel

    2011-01-01

    Flow velocity through a research reactor core composed by MTR-type fuel elements is investigated. Core cooling capacity must be available at the same time that fuel-plate collapse must be avoided. Fuel plates do not rupture during plate collapse, but their lateral deflections can close flow channels and lead to plate over-heating. The critical flow velocity is a speed at which the plates collapse by static instability type failure. In this paper, critical velocity and coolant velocity are evaluated for a typical MTR-type flat plate fuel element. Miller's method is used for prediction of critical velocity. The coolant velocity is limited to 2/3 of the critical velocity, that is a currently used criterion. Fuel plate characteristics are based on the open pool Australian light water reactor. (author)

  12. Direct numerical simulations of reacting flows with detailed chemistry using many-core/GPU acceleration

    KAUST Repository

    Hernández Pérez, Francisco E.

    2018-03-29

    A new direct numerical simulation (DNS) code for multi-component gaseous reacting flows has been developed at KAUST, with the state-of-the-art programming model for next generation high performance computing platforms. The code, named KAUST Adaptive Reacting Flows Solver (KARFS), employs the MPI+X programming, and relies on Kokkos for “X” for performance portability to multi-core, many-core and GPUs, providing innovative software development while maintaining backward compatibility with established parallel models and legacy code. The capability and potential of KARFS to perform DNS of reacting flows with large, detailed reaction mechanisms is demonstrated with various model problems involving ignition and turbulent flame propagations with varying degrees of chemical complexities.

  13. Integrated Surface/subsurface flow modeling in PFLOTRAN

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Scott L [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    Understanding soil water, groundwater, and shallow surface water dynamics as an integrated hydrological system is critical for understanding the Earth’s critical zone, the thin outer layer at our planet’s surface where vegetation, soil, rock, and gases interact to regulate the environment. Computational tools that take this view of soil moisture and shallow surface flows as a single integrated system are typically referred to as integrated surface/subsurface hydrology models. We extend the open-source, highly parallel, subsurface flow and reactive transport simulator PFLOTRAN to accommodate surface flows. In contrast to most previous implementations, we do not represent a distinct surface system. Instead, the vertical gradient in hydraulic head at the land surface is neglected, which allows the surface flow system to be eliminated and incorporated directly into the subsurface system. This tight coupling approach leads to a robust capability and also greatly simplifies implementation in existing subsurface simulators such as PFLOTRAN. Successful comparisons to independent numerical solutions build confidence in the approximation and implementation. Example simulations of the Walker Branch and East Fork Poplar Creek watersheds near Oak Ridge, Tennessee demonstrate the robustness of the approach in geometrically complex applications. The lack of a robust integrated surface/subsurface hydrology capability had been a barrier to PFLOTRAN’s use in critical zone studies. This work addresses that capability gap, thus enabling PFLOTRAN as a community platform for building integrated models of the critical zone.

  14. Analysis of energy flow during playground surface impacts.

    Science.gov (United States)

    Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

    2013-10-01

    The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously obtained data from children performing an exercise involving freefalling with a fully extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downward. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods.

  15. The Influence of Slope Breaks on Lava Flow Surface Disruption

    Science.gov (United States)

    Glaze, Lori S.; Baloga, Stephen M.; Fagents, Sarah A.; Wright, Robert

    2014-01-01

    Changes in the underlying slope of a lava flow impart a significant fraction of rotational energy beyond the slope break. The eddies, circulation and vortices caused by this rotational energy can disrupt the flow surface, having a significant impact on heat loss and thus the distance the flow can travel. A basic mechanics model is used to compute the rotational energy caused by a slope change. The gain in rotational energy is deposited into an eddy of radius R whose energy is dissipated as it travels downstream. A model of eddy friction with the ambient lava is used to compute the time-rate of energy dissipation. The key parameter of the dissipation rate is shown to be rho R(sup 2/)mu, where ? is the lava density and mu is the viscosity, which can vary by orders of magnitude for different flows. The potential spatial disruption of the lava flow surface is investigated by introducing steady-state models for the main flow beyond the steepening slope break. One model applies to slow-moving flows with both gravity and pressure as the driving forces. The other model applies to fast-moving, low-viscosity, turbulent flows. These models provide the flow velocity that establishes the downstream transport distance of disrupting eddies before they dissipate. The potential influence of slope breaks is discussed in connection with field studies of lava flows from the 1801 Hualalai and 1823 Keaiwa Kilauea, Hawaii, and 2004 Etna eruptions.

  16. Reactor core flow measurements during plant start-up using non-intrusive flow meter CROSSFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Kanda, V.; Sharp, B.; Gurevich, A., E-mail: vkanda@amag-inc.com, E-mail: bsharp@amag-inc.com, E-mail: agurevich@amag-inc.com [Advanced Measurement & Analysis Group Inc., Ontario (Canada); Gurevich, Y., E-mail: yuri.gurevich@daystartech.ca [Daystar Technologies Inc., Ontario (Canada); Selvaratnarajah, S.; Lopez, A., E-mail: sselvaratnarajah@amag-inc.com, E-mail: alopez@amag-inc.com [Advanced Measurement & Analysis Group Inc., Ontario (Canada)

    2013-07-01

    For the first time, direct measurements of the total reactor coolant flow and the flow distribution between the inner reactor zone and the outer zone were conducted using the non-intrusive clamp on ultrasonic cross-correlation flow meter, CROSSFLOW, developed and manufactured by Advanced Measurement & Analysis Group Inc. (AMAG). The measurements were performed at Bruce Power A Unit 1 on the Pump Discharge piping of the Primary Heat Transport (PHT) system during start-up. This paper describes installation processes, hydraulic testing, uncertainty analysis and traceability of the measurements to certified standards. (author)

  17. Size-Dependent Specific Surface Area of Nanoporous Film Assembled by Core-Shell Iron Nanoclusters

    Directory of Open Access Journals (Sweden)

    Jiji Antony

    2006-01-01

    Full Text Available Nanoporous films of core-shell iron nanoclusters have improved possibilities for remediation, chemical reactivity rate, and environmentally favorable reaction pathways. Conventional methods often have difficulties to yield stable monodispersed core-shell nanoparticles. We produced core-shell nanoclusters by a cluster source that utilizes combination of Fe target sputtering along with gas aggregations in an inert atmosphere at 7∘C. Sizes of core-shell iron-iron oxide nanoclusters are observed with transmission electron microscopy (TEM. The specific surface areas of the porous films obtained from Brunauer-Emmett-Teller (BET process are size-dependent and compared with the calculated data.

  18. Evolution of - and Core-Dominated Lava Flows Using Scaling Analysis

    Science.gov (United States)

    Castruccio, A.; Rust, A.; Sparks, R. S.

    2010-12-01

    We investigated the front evolution of simple lava flows on a slope using scaling arguments. For the retarding force acting against gravity, we analyzed three different cases: a flow controlled by a Newtonian viscosity, a flow controlled by the yield strength of a diffusively growing crust and a flow controlled by its core yield strength. These models were tested using previously published data of front evolution and volume discharge of 10 lava flow eruptions from 6 different volcanoes. Our analysis suggests that for basaltic eruptions with high effusion rate and low crystal content, (Hawaiian eruptions), the best fit of the data is with a Newtonian viscosity. For basaltic eruptions with lower effusion rates (Etna eruptions) or long duration andesitic eruptions (Lonquimay eruption, Chile) the flow is controlled by the yield strength of a growing crust. Finally, for very high crystalline lavas (Colima, Santiaguito) the flow is controlled by its core yield strength. The order of magnitude of the viscosities from our analysis is in the same range as previous studies using field measurements on the same lavas. The yield strength values for the growing crust and core of the flow are similar and with an order of magnitude of 10^5 Pa. This number is similar to yield strength values found in lava domes by different authors. The consistency of yield strength ~10^5 Pa is because larger stresses cause fracturing of very crystalline magma, which drastically reduces its effective strength. Furthermore, we used a 2-D analysis of a Bingham fluid flow on a slope to conclude that, for lower yield strength values, the flow is controlled mainly by its plastic viscosity and the lava can be effectively modelled as Newtonian. Our analysis provides a simple tool to evaluate the main controlling forces in the evolution of a lava flow, as well as the magnitude of its rheological properties, for eruptions of different compositions and conditions and may be useful to predict the evolution of

  19. Activity of corrosion products in pool type reactors with ascending flow in the core

    International Nuclear Information System (INIS)

    Andrade e Silva, Graciete S. de; Queiroz Bogado Leite, Sergio de

    1995-01-01

    A model for the activity of corrosion products in the water of a pool type reactor with ascending flow is presented. The problem is described by a set of coupled differential equations relating the radioisotope concentrations in the core and pool circuits and taking into account two types of radioactive sources: i) those from radioactive species formed in the fuel cladding, control elements, reflector, etc, and afterwards released to the primary stream by corrosion (named reactor sources) and ii) those formed from non radioactive isotopes entering the primary stream by corrosion of the circuit components and being activated when passing through the core (named circuit sources). (author). 6 refs, 3 figs, 4 tabs

  20. Optimization of High-Resolution Continuous Flow Analysis for Transient Climate Signals in Ice Cores

    DEFF Research Database (Denmark)

    Bigler, Matthias; Svensson, Anders; Kettner, Ernesto

    2011-01-01

    Over the past two decades, continuous flow analysis (CFA) systems have been refined and widely used to measure aerosol constituents in polar and alpine ice cores in very high-depth resolution. Here we present a newly designed system consisting of sodium, ammonium, dust particles, and electrolytic...... meltwater conductivity detection modules. The system is optimized for high- resolution determination of transient signals in thin layers of deep polar ice cores. Based on standard measurements and by comparing sections of early Holocene and glacial ice from Greenland, we find that the new system features...

  1. A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster

    Science.gov (United States)

    McDonald, M.; Bayliss, M.; Benson, B. A.; Foley, R. J.; Ruel, J.; Sullivan, P.; Veilleux, S.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; hide

    2012-01-01

    In the cores of some galaxy clusters the hot intracluster plasma is dense enough that it should cool radiatively in the cluster s lifetime, leading to continuous "cooling flows" of gas sinking towards the cluster center, yet no such cooling flow has been observed. The low observed star formation rates and cool gas masses for these "cool core" clusters suggest that much of the cooling must be offset by astrophysical feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical, and infrared observations of the galaxy cluster SPT-CLJ2344-4243 at z = 0.596. These observations reveal an exceptionally luminous (L(sub 2-10 keV) = 8.2 10(exp 45) erg/s) galaxy cluster which hosts an extremely strong cooling flow (M(sub cool) = 3820 +/- 530 Stellar Mass/yr). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (740 +/- 160 Stellar Mass/ yr), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form via accretion of the intracluster medium, rather than the current picture of central galaxies assembling entirely via mergers.

  2. Investigation of two-phase flow instability under SMART-P core conditions

    International Nuclear Information System (INIS)

    Hwang, Dae Hyun; Lee, Chung Chan

    2005-01-01

    An integral-type advanced light water reactor, named SMART-P, is being continuously studied at KAERI. The reactor core consists of hundreds of closed-channel type fuel assemblies with vertical upward flows. The upper and lower parts of the fuel assembly channels are connected to the common heads. The constant pressure drop imposed on the channel is responsible for the occurrence of density wave oscillations under local boiling and/or natural circulation conditions. The fuel assembly channel with oscillatory flow is highly susceptible to experience the CHF which may cause the fuel failure due to a sudden increase of the cladding temperature. Thus, prevention of the flow instability is an important criterion for the SMART-P core design. Experimental and analytical studies have been conducted in order to investigate the onset of flow instability (OFI) under SMART core conditions. The parallel channel oscillations were observed in a high pressure water-loop test facility. A linear stability analysis model in the frequency-domain was developed for the prediction of the marginal stability boundary (MSB) in the parallel boiling channels

  3. Local mesh refinement for incompressible fluid flow with free surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Terasaka, H.; Kajiwara, H.; Ogura, K. [Tokyo Electric Power Company (Japan)] [and others

    1995-09-01

    A new local mesh refinement (LMR) technique has been developed and applied to incompressible fluid flows with free surface boundaries. The LMR method embeds patches of fine grid in arbitrary regions of interest. Hence, more accurate solutions can be obtained with a lower number of computational cells. This method is very suitable for the simulation of free surface movements because free surface flow problems generally require a finer computational grid to obtain adequate results. By using this technique, one can place finer grids only near the surfaces, and therefore greatly reduce the total number of cells and computational costs. This paper introduces LMR3D, a three-dimensional incompressible flow analysis code. Numerical examples calculated with the code demonstrate well the advantages of the LMR method.

  4. Heat Flow In Cylindrical Bodies During Laser Surface Transformation Hardening

    Science.gov (United States)

    Sandven, Ole A.

    1980-01-01

    A mathematical model for the transient heat flow in cylindrical specimens is presented. The model predicts the temperature distribution in the vicinity of a moving ring-shaped laser spot around the periphery of the outer surface of a cylinder, or the inner surface of a hollow cylinder. It can be used to predict the depth of case in laser surface transformation hardening. The validity of the model is tested against experimental results obtained on SAE 4140 steel.

  5. CoreFlow: a computational platform for integration, analysis and modeling of complex biological data.

    Science.gov (United States)

    Pasculescu, Adrian; Schoof, Erwin M; Creixell, Pau; Zheng, Yong; Olhovsky, Marina; Tian, Ruijun; So, Jonathan; Vanderlaan, Rachel D; Pawson, Tony; Linding, Rune; Colwill, Karen

    2014-04-04

    A major challenge in mass spectrometry and other large-scale applications is how to handle, integrate, and model the data that is produced. Given the speed at which technology advances and the need to keep pace with biological experiments, we designed a computational platform, CoreFlow, which provides programmers with a framework to manage data in real-time. It allows users to upload data into a relational database (MySQL), and to create custom scripts in high-level languages such as R, Python, or Perl for processing, correcting and modeling this data. CoreFlow organizes these scripts into project-specific pipelines, tracks interdependencies between related tasks, and enables the generation of summary reports as well as publication-quality images. As a result, the gap between experimental and computational components of a typical large-scale biology project is reduced, decreasing the time between data generation, analysis and manuscript writing. CoreFlow is being released to the scientific community as an open-sourced software package complete with proteomics-specific examples, which include corrections for incomplete isotopic labeling of peptides (SILAC) or arginine-to-proline conversion, and modeling of multiple/selected reaction monitoring (MRM/SRM) results. CoreFlow was purposely designed as an environment for programmers to rapidly perform data analysis. These analyses are assembled into project-specific workflows that are readily shared with biologists to guide the next stages of experimentation. Its simple yet powerful interface provides a structure where scripts can be written and tested virtually simultaneously to shorten the life cycle of code development for a particular task. The scripts are exposed at every step so that a user can quickly see the relationships between the data, the assumptions that have been made, and the manipulations that have been performed. Since the scripts use commonly available programming languages, they can easily be

  6. Structural dependence of the 5d-metal surface energies as deduced from surface core-level shift measurements

    International Nuclear Information System (INIS)

    Mrartensson, N.; Saalfeld, H.B.; Kuhlenbeck, H.; Neumann, M.

    1989-01-01

    Surface core-level shift measurements performed at the BESSY storage ring yield -0.41(2) eV for Os(0001) and 0.00(10) eV for Re(0001). An analysis of the surface shifts in the 5d transition series shows that the surface energy as a function of Z has a maximum at lower Z for the bcc phase than for the fcc-hcp phases, at W and between Re and Os, respectively

  7. Slit-surface electrospinning: a novel process developed for high-throughput fabrication of core-sheath fibers.

    Directory of Open Access Journals (Sweden)

    Xuri Yan

    Full Text Available In this work, we report on the development of slit-surface electrospinning--a process that co-localizes two solutions along a slit surface to spontaneously emit multiple core-sheath cone-jets at rates of up to 1 L/h. To the best of our knowledge, this is the first time that production of electrospun core-sheath fibers has been scaled to this magnitude. Fibers produced in this study were defect-free (i.e. non-beaded and core-sheath geometry was visually confirmed under scanning electron microscopy. The versatility of our system was demonstrated by fabrication of (1 fibers encapsulating a drug, (2 bicomponent fibers, (3 hollow fibers, and (4 fibers from a polymer that is not normally electrospinnable. Additionally, we demonstrate control of the process by modulating parameters such as flow rate, solution viscosity, and fixture design. The technological achievements demonstrated in this work significantly advance core-sheath electrospinning towards commercial and manufacturing viability.

  8. Cladding defects in hollow core fibers for surface mode suppression and improved birefringence

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Lyngso, J. K.; Lægsgaard, Jesper

    2014-01-01

    We demonstrate a novel polarization maintaining hollow-core photonic bandgap fiber geometry that reduces the impact of surface modes on fiber transmission. The cladding structure is modified with a row of partially collapsed holes to strip away unwanted surface modes. A theoretical investigation...... of the surface mode stripping is presented and compared to the measured performance of four 7-cells core fibers that were drawn with different collapse ratio of the defects. The varying pressure along the defect row in the cladding during drawing introduces an ellipticity of the core. This, combined...... with the presence of antiresonant features on the core wall, makes the fibers birefringent, with excellent polarization maintaining properties. (C) 2014 Optical Society of America...

  9. Backward flow in a surface tension driven micropump

    International Nuclear Information System (INIS)

    Ju, Jongil; Park, Joong Yull; Lee, Sang-Hoon; Kim, Kyung Chun; Kim, Hyundong; Berthier, Erwin; Beebe, David J

    2008-01-01

    A surface tension driven micropump harnessing the pressure difference generated by drops of different curvature radii proves to be a simple and attractive passive method to drive fluid flow in microdevices. Here we observed the appearance of backward flow when the initial sizes of the droplets at the inlet and outlet ports are similar. To explain this phenomenon several hypotheses have been investigated. Consideration of the inertia of the fluid in the channel revealed that it alone is insufficient to explain the observed backward flow. We discovered that rotational flow inside the outlet droplet could be a source of inertia, explaining the generation of the backward flow. In addition, we have experimentally determined that the ratio of the volumes of the initial outlet drop and inlet drop correlates with the occurrence of the backward flow. (note)

  10. Study on surface wave characteristics of free surface flow of liquid metal lithium for IFMIF

    International Nuclear Information System (INIS)

    Hoashi, Eiji; Sugiura, Hirokazu; Yoshihashi-Suzuki, Sachiko; Yamaoka, Nobuo; Horiike, Hiroshi; Kanemura, Takuji; Kondo, Hiroo

    2011-01-01

    The international fusion materials irradiation facility (IFMIF) presents an intense neutron source to develop fusion reactor materials. The free surface flow of a liquid metal Lithium (Li) is planned as a target irradiated by two deuteron beams to generate intense neutrons and it is thus important to obtain knowledge of the surface wave characteristic for the safety and the efficiency of system in the IFMIF. We have been studying on surface wave characteristics experimentally using the liquid metal Li circulation facility at Osaka University and numerically using computational fluid dynamics (CFD) code, FLUENT. This paper reports the results of the surface fluctuation, the wave height and the surface velocity in the free surface flow of the liquid metal Li examined experimentally and numerically. In the experiment, an electro-contact probe apparatus was used to obtain the surface fluctuation and the wave height, and a high speed video was used to measure the surface velocity. We resulted in knowledge of the surface wave growth mechanism. On the other hand, a CFD simulation was also conducted to obtain information on the relation of the free surface with the inner flow. In the simulation, the model included from a two-staged contraction nozzle to a flow channel with a free surface flow region and simulation results were compared with the experimental data. (author)

  11. Measurements of the near-surface flow over a hill

    Science.gov (United States)

    Vosper, S. B.; Mobbs, S. D.; Gardiner, B. A.

    2002-10-01

    The near-surface flow over a hill with moderate slope and height comparable with the boundary-layer depth is investigated through field measurements of the mean flow (at 2 m), surface pressure, and turbulent momentum flux divergence between 8 and 15 m. The measurements were made along an east-west transect across the hill Tighvein (height 458 m, approximate width 8 km) on the Isle of Arran, south-west Scotland, during two separate periods, each of around three-weeks duration. Radiosonde ascents are used to determine the variation of a Froude number, FL = U/NL, where U is the wind speed at the middle-layer height, hm, N is the mean Brunt-Väisälä frequency below this height and L is a hill length-scale. Measurements show that for moderately stratified flows (for which FL 0.25) a minimum in the hill-induced surface-pressure perturbation occurs across the summit and this is accompanied by a maximum in the near-surface wind speed. In the more strongly stratified case (FL 0.25) the pressure field is more asymmetric and the lee-slope flow is generally stronger than on the windward slope. Such a flow pattern is qualitatively consistent with that predicted by stratified linear boundary-layer and gravity-wave theories. The near-surface momentum budget is analysed by evaluating the dominant terms in a Bernoulli equation suitable for turbulent flow. Measurements during periods of westerly flow are used to evaluate the dominant terms, and the equation is shown to hold to a reasonable approximation on the upwind slope of the hill and also on the downwind slope, away from the summit. Immediately downwind of the summit, however, the Bernoulli equation does not hold. Possible reasons for this, such as non-separated sheltering and flow separation, are discussed.

  12. Experiments on graphite block gaps connected with leak flow in bottom-core structure of experimental very high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Kikuchi, Kenji; Futakawa, Masatoshi; Takizuka, Takakazu; Kaburaki, Hideo; Sanokawa, Konomo

    1984-01-01

    In order to minimize the leak flow rate of an experimental VHTR (a multi-purpose very high-temperature gas-cooled reactor), the graphite blocks are tightened to reduce the gap distance between blocks by core restrainers surrounded outside of the fixed reflectors of the bottom-core structure and seal elements are placed in the gaps. By using a 1/2.75-scale model of the bottom-core structure, the experiments on the following items have been carried out: a relationship between core restraint force and block gap, a relationship between core restraint force and inclined angle of the model, leak flow characteristics of seal elements etc. The conclusions derived from the experiments are as follows: (1) Core restraint force is significantly effective for decreasing the gap distance between hot plenum blocks, but ineffective for the gap between hot plenum block and fixed reflector. (2) Graphite seal element reduces the leak flow rate from the top surface of hot plenum block into plenum region to one-third. (author)

  13. Tidally-driven Surface Flow in a Georgia Estuarine Saltmarsh

    Science.gov (United States)

    Young, D.; Bruder, B. L.; Haas, K. A.; Webster, D. R.

    2016-02-01

    Estuarine saltmarshes are diverse, valuable, and productive ecosystems. Vegetation dampens wave and current energy, thereby allowing the estuaries to serve as a nursery habitat for shellfish and fish species. Tidally-driven flow transports nutrients into and out of the estuary, nourishing inshore and offshore vegetation and animals. The effects of vegetation on the marsh hydrodynamics and on the estuary creek and channel flow are, unfortunately, poorly understood, and the knowledge that does exist primarily originates from modeling studies. Field studies addressing marsh surface flows are limited due to the difficulty of accurately measuring the water surface elevation and acquiring concurrent velocity measurements in the dense marsh vegetation. This study partially bridges the gap between the model observations of marsh flow driven by water surface elevation gradients and flume studies of flow through vegetation. Three current meters and three pressure transducers were deployed for three days along a transect perpendicular to the main channel (Little Ogeechee River) in a saltmarsh adjacent to Rose Dhu Island (Savannah, Georgia, USA). The pressure transducer locations were surveyed daily with static GPS yielding highly accurate water surface elevation data. During flood and ebb tide, water surface elevation differences between the marsh and Little Ogeechee River were observed up to 15 cm and pressure gradients were observed up to 0.0017 m of water surface elevation drop per m of linear distance. The resulting channel-to-saltmarsh pressure gradients substantially affected tidal currents at all current meters. At one current meter, the velocity was nearly perpendicular to the Little Ogeechee River bank. The velocity at this location was effectively modeled as a balance between the pressure gradient and marsh vegetation-induced drag force using the Darcy-Weisbach/Lindner's equations developed for flow-through-vegetation analysis in open channel flow.

  14. Hydraulic investigation on free surface flow of windowless target

    International Nuclear Information System (INIS)

    Hu Chen; Gu Hanyang

    2015-01-01

    The formation and control of free surface are the most essential parts in the studies of windowless target in ACCELERATOR-DRIVEN sub-critical system (ADS). Water model experiments and 360° full scale three dimensional simulations were conducted. The experimental study demonstrates that the free surface is significantly affected by the inlet flow velocity and outlet pressure. The length of free surface decreases in the second order with the increase of inlet flow velocity, while it decreases linearly with the outlet pressure. The structure and feature of flow field were investigated. The results show that the free surface is vulnerable to the vortex movement. Transient simulations were performed with volume of fluid (VOF) method, large eddy simulation (LES) and the pressure implicit with splitting of operators (PISO) algorithm. The simulation results agree qualitatively well with the experimental data related to both free surface flow and flow field. These simulation models and methods are proved to be applicable in the hydraulic simulations of liquid heavy metal target. (authors)

  15. A High-Resolution Continuous Flow Analysis System for Polar Ice Cores

    DEFF Research Database (Denmark)

    Dallmayr, Remi; Goto-Azuma, Kumiko; Kjær, Helle Astrid

    2016-01-01

    of Polar Research (NIPR) in Tokyo. The system allows the continuous analysis of stable water isotopes and electrical conductivity, as well as the collection of discrete samples from both inner and outer parts of the core. This CFA system was designed to have sufficiently high temporal resolution to detect...... signals of abrupt climate change in deep polar ice cores. To test its performance, we used the system to analyze different climate intervals in ice drilled at the NEEM (North Greenland Eemian Ice Drilling) site, Greenland. The quality of our continuous measurement of stable water isotopes has been......In recent decades, the development of continuous flow analysis (CFA) technology for ice core analysis has enabled greater sample throughput and greater depth resolution compared with the classic discrete sampling technique. We developed the first Japanese CFA system at the National Institute...

  16. Fundamental study on flow characteristics of disrupted core pool at a low energy level (Joint research)

    International Nuclear Information System (INIS)

    Morita, Koji; Liu, Ping; Matsumoto, Tatsuya; Fukuda, Kenji; Tobita, Yoshiharu; Sato, Ikken

    2007-03-01

    Dynamic behaviors of solid particle beds in a liquid pool against pressure transients were investigated to model the mobility of core materials in a low-energy disrupted core of a liquid metal fast reactor. A series of experiments was performed with a particle bed of different heights, comprising different monotype solid particles, where variable initial pressures of the originally pressurized nitrogen gas were adopted as the pressure source. Computational simulations of the experiments were performed using SIMMER-III, a fast reactor safety analysis code. Experimental analyses using the SIMMER-III code show that physical models and method used in the code can reasonably represent the transient behaviors of multiphase flows with rich solid phase as observed in the experiments. The validation of several key models of SIMMER-III was also discussed for treating transient behaviors of the solid-particle phase in multiphase flows. (author)

  17. Vortex cores and vortex motion in superconductors with anisotropic Fermi surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Galvis, J.A. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Departamento de Ciencias Naturales, Facultad de ingeniería y Ciencias Básicas, Universidad Central, Bogotá (Colombia); National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Herrera, E.; Guillamón, I.; Vieira, S. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Unidad Asociada de Altos Campos Magnéticos y Bajas Temperaturas, UAM, CSIC, Madrid (Spain); Suderow, H., E-mail: hermann.suderow@uam.es [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Unidad Asociada de Altos Campos Magnéticos y Bajas Temperaturas, UAM, CSIC, Madrid (Spain)

    2017-02-15

    Highlights: • The observation of vortex cores is reviewed, with emphasis in new experiments. • Vortex cores are follow superconducting gap and Fermi surface shapes. • The vortex core shape influences vortex dynamics. - Abstract: Explaning static and dynamic properties of the vortex lattice in anisotropic superconductors requires a careful characterization of vortex cores. The vortex core contains Andreev bound states whose spatial extension depends on the anisotropy of the electronic band-structure and superconducting gap. This might have an impact on the anisotropy of the superconducting properties and on vortex dynamics. Here we briefly summarize basic concepts to understand anisotropic vortex cores and review vortex core imaging experiments. We further discuss moving vortex lattices and the influence of vortex core shape in vortex motion. We find vortex motion in highly tilted magnetic fields. We associate vortex motion to the vortex entry barrier and the screening currents at the surface. We find preferential vortex motion along the main axis of the vortex lattice. After travelling integers of the intervortex distance, we find that vortices move more slowly due to the washboard potential of the vortex lattice.

  18. Vortex cores and vortex motion in superconductors with anisotropic Fermi surfaces

    International Nuclear Information System (INIS)

    Galvis, J.A.; Herrera, E.; Guillamón, I.; Vieira, S.; Suderow, H.

    2017-01-01

    Highlights: • The observation of vortex cores is reviewed, with emphasis in new experiments. • Vortex cores are follow superconducting gap and Fermi surface shapes. • The vortex core shape influences vortex dynamics. - Abstract: Explaning static and dynamic properties of the vortex lattice in anisotropic superconductors requires a careful characterization of vortex cores. The vortex core contains Andreev bound states whose spatial extension depends on the anisotropy of the electronic band-structure and superconducting gap. This might have an impact on the anisotropy of the superconducting properties and on vortex dynamics. Here we briefly summarize basic concepts to understand anisotropic vortex cores and review vortex core imaging experiments. We further discuss moving vortex lattices and the influence of vortex core shape in vortex motion. We find vortex motion in highly tilted magnetic fields. We associate vortex motion to the vortex entry barrier and the screening currents at the surface. We find preferential vortex motion along the main axis of the vortex lattice. After travelling integers of the intervortex distance, we find that vortices move more slowly due to the washboard potential of the vortex lattice.

  19. Toward Understanding Tip Leakage Flows in Small Compressor Cores Including Stator Leakage Flow

    Science.gov (United States)

    Berdanier, Reid A.; Key, Nicole L.

    2017-01-01

    The focus of this work was to provide additional data to supplement the work reported in NASA/CR-2015-218868 (Berdanier and Key, 2015b). The aim of that project was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearances were studied with nominal tip clearance gaps of 1.5 percent, 3.0 percent, and 4.0 percent based on a constant annulus height. Overall compressor performance was previously investigated at four corrected speedlines (100 percent, 90 percent, 80 percent, and 68 percent) for each of the three tip clearance configurations. This study extends the previously published results to include detailed steady and time-resolved pressure data at two loading conditions, nominal loading (NL) and high loading (HL), on the 100 percent corrected speedline for the intermediate clearance level (3.0 percent). Steady detailed radial traverses of total pressure at the exit of each stator row are supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data were combined with existing three-component velocity measurements to identify a novel technique for calculating blockage in a multistage compressor. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100 percent corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements reveal new knowledge about the

  20. Dynamic surface-pressure instrumentation for rods in parallel flow

    International Nuclear Information System (INIS)

    Mulcahy, T.M.; Lawrence, W.

    1979-01-01

    Methods employed and experience gained in measuring random fluid boundary layer pressures on the surface of a small diameter cylindrical rod subject to dense, nonhomogeneous, turbulent, parallel flow in a relatively noise-contaminated flow loop are described. Emphasis is placed on identification of instrumentation problems; description of transducer construction, mounting, and waterproofing; and the pretest calibration required to achieve instrumentation capable of reliable data acquisition

  1. Dynamics and Instabilities of Free Surface and Vortex Flows

    DEFF Research Database (Denmark)

    Tophøj, Laust Emil Hjerrild

    2012-01-01

    This PhD thesis consists of two main parts. The first part describes the dynamics of an ideal fluid on a stationary free surface of a given shape. It turns out that one can formulate a set of self-contained equations of momentum conservation for the tangential flow, with no reference to the flow ......)]. Finally, an experimental work on elastic collisions of wet spheres is briefly discussed....

  2. Features and validation of discrete element method for simulating pebble flow in reactor core

    International Nuclear Information System (INIS)

    Xu Yong; Li Yanjie

    2005-01-01

    The core of a High-Temperature Gas-cooled Reactor (HTGR) is composed of big number of fuel pebbles, their kinetic behaviors are of great importance in estimating the path and residence time of individual pebble, the evolution of the mixing zone for the assessment of the efficiency of a reactor. Numerical method is highlighted in modern reactor design. In view of granular flow, the Discrete Element Model based on contact mechanics of spheres was briefly described. Two typical examples were presented to show the capability of the DEM method. The former is piling with glass/steel spheres, which provides validated evidences that the simulated angles of repose are in good coincidence with the experimental results. The later is particle discharge in a flat- bottomed silo, which shows the effects of material modulus and demonstrates several features. The two examples show the DEM method enables to predict the behaviors, such as the evolution of pebble profiles, streamlines etc., and provides sufficient information for pebble flow analysis and core design. In order to predict the cyclic pebble flow in a HTGR core precisely and efficiently, both model and code improvement are needed, together with rational specification of physical properties with proper measuring techniques. Strategic and methodological considerations were also discussed. (authors)

  3. Radionuclide transfer onto ground surface in surface water flow. 2. Undisturbed tuff rock

    International Nuclear Information System (INIS)

    Mukai, Masayuki; Takebe, Shinichi; Komiya, Tomokazu

    1994-09-01

    Radionuclide migration with ground surface water flow is considered to be one of path ways in the scenario for environmental migration of the radionuclide leaked from LLRW depository. To study the radionuclide migration demonstratively, a ground surface radionuclide migration test was carried out by simulating radioactive solution flowing on the sloped tuff rock surface. Tuff rock sample of 240 cm in length taken from the Shimokita district was used to test the transfer of 60 Co, 85 Sr and 137 Cs onto the sample surface from the flowing radioactive solution under restricted infiltration condition at flow rates of 25, 80, 160ml/min and duration of 56h. The concentration change of the radionuclides in effluent was nearly constant as a function of elapsed time during the experimental period, but decreased with lower flow rates. Among the three radionuclides, 137 Cs was greatly decreased its concentration to 30% of the inflow. Adsorbed distribution of the radionuclides concentration on the ground surface decreased gradually with the distance from the inlet, and showed greater gradient at lower flow rate. Analyzing the result by the migration model, where a vertical advection distribution and two-dimensional diffusion in surface water are adopted with a first order adsorption reaction, value of migration parameters was obtained relating to the radionuclide adsorption and the surface water flow, and the measured distribution could be well simulated by adopting the value to the model. By comparing the values with the case of loamy soil layer, all values of the migration parameters showed not so great difference between two samples for 60 Co and 85 Sr. For 137 Cs, reflecting a few larger value of adsorption to the tuff rock, larger ability to reduce the concentration of flowing radioactive solution could be indicated than that to the loamy soil surface by estimation for long flowed distance. (author)

  4. Near-surface flow of volcanic gases on Io

    International Nuclear Information System (INIS)

    Lee, S.W.; Thomas, P.C.

    1980-01-01

    Significant near-surface flow of gas several hundred kilometers from Pele (Plume 1) on Io is indicated by a series of bright, elongate albedo markings. Particles produced at small, local vents are apparently carried as much as 70 km farther 'downwind' from Pele. The gas densities and velocities necessary to suspend 0.1 to 10 micron particles at such a distance imply mass flow rates of 10 to the 7th - 10 to the 9th g/sec. Such flow rates are consistent with other estimates of mass transport by the plume. The large flow rates so far from the source allow an estimate of the rate of resurfacing of Io by lava flows and pyroclastics that is independent of estimates based on meteorite flux or on the amount of solids carried within the plumes themselves

  5. Flow of viscous fluid along an exponentially stretching curved surface

    Directory of Open Access Journals (Sweden)

    N.F. Okechi

    Full Text Available In this paper, we present the boundary layer analysis of flow induced by rapidly stretching curved surface with exponential velocity. The governing boundary value problem is reduced into self-similar form using a new similarity transformation. The resulting equations are solved numerically using shooting and Runge-Kutta methods. The numerical results depicts that the fluid velocity as well as the skin friction coefficient increases with the surface curvature, similar trend is also observed for the pressure. The dimensionless wall shear stress defined for this problem is greater than that of a linearly stretching curved surface, but becomes comparably less for a surface stretching with a power-law velocity. In addition, the result for the plane surface is a special case of this study when the radius of curvature of the surface is sufficiently large. The numerical investigations presented in terms of the graphs are interpreted with the help of underlying physics of the fluid flow and the consequences arising from the curved geometry. Keywords: Boundary layer flow, Curved surface, Exponential stretching, Curvature

  6. Spatial connectivity in a highly heterogeneous aquifer: From cores to preferential flow paths

    Science.gov (United States)

    Bianchi, M.; Zheng, C.; Wilson, C.; Tick, G.R.; Liu, Gaisheng; Gorelick, S.M.

    2011-01-01

    This study investigates connectivity in a small portion of the extremely heterogeneous aquifer at the Macrodispersion Experiment (MADE) site in Columbus, Mississippi. A total of 19 fully penetrating soil cores were collected from a rectangular grid of 4 m by 4 m. Detailed grain size analysis was performed on 5 cm segments of each core, yielding 1740 hydraulic conductivity (K) estimates. Three different geostatistical simulation methods were used to generate 3-D conditional realizations of the K field for the sampled block. Particle tracking calculations showed that the fastest particles, as represented by the first 5% to arrive, converge along preferential flow paths and exit the model domain within preferred areas. These 5% fastest flow paths accounted for about 40% of the flow. The distribution of preferential flow paths and particle exit locations is clearly influenced by the occurrence of clusters formed by interconnected cells with K equal to or greater than the 0.9 decile of the data distribution (10% of the volume). The fraction of particle paths within the high-K clusters ranges from 43% to 69%. In variogram-based K fields, some of the fastest paths are through media with lower K values, suggesting that transport connectivity may not require fully connected zones of relatively homogenous K. The high degree of flow and transport connectivity was confirmed by the values of two groups of connectivity indicators. In particular, the ratio between effective and geometric mean K (on average, about 2) and the ratio between the average arrival time and the arrival time of the fastest particles (on average, about 9) are consistent with flow and advective transport behavior characterized by channeling along preferential flow paths. ?? 2011 by the American Geophysical Union.

  7. Surface Runoff in Watershed Modeling—Turbulent or Laminar Flows?

    Directory of Open Access Journals (Sweden)

    Mark E. Grismer

    2016-05-01

    Full Text Available Determination of overland sheet flow depths, velocities and celerities across the hillslope in watershed modeling is important towards estimation of surface storage, travel times to streams and soil detachment rates. It requires careful characterization of the flow processes. Similarly, determination of the temporal variation of hillslope-riparian-stream hydrologic connectivity requires estimation of the shallow subsurface soil hydraulic conductivity and soil-water retention (i.e., drainable porosities parameters. Field rainfall and runoff simulation studies provide considerable information and insight into these processes; in particular, that sheet flows are likely laminar and that shallow hydraulic conductivities and storage can be determined from the plot studies. Here, using a 1 m by 2 m long runoff simulation flume, we found that for overland flow rates per unit width of roughly 30–60 mm2/s and bedslopes of 10%–66% with varying sand roughness depths that all flow depths were predicted by laminar flow equations alone and that equivalent Manning’s n values were depth dependent and quite small relative to those used in watershed modeling studies. Even for overland flow rates greater than those typically measured or modeled and using Manning’s n values of 0.30–0.35, often assumed in physical watershed model applications for relatively smooth surface conditions, the laminar flow velocities were 4–5 times greater, while the laminar flow depths were 4–5 times smaller. This observation suggests that travel times, surface storage volumes and surface shear stresses associated with erosion across the landscape would be poorly predicted using turbulent flow assumptions. Filling the flume with fine sand and conducting runoff studies, we were unable to produce sheet flow, but found that subsurface flows were onflow rate, soil depth and slope dependent and drainable porosities were only soil depth and slope dependent. Moreover, both the sand

  8. Flow profiling of a surface-acoustic-wave nanopump

    Science.gov (United States)

    Guttenberg, Z.; Rathgeber, A.; Keller, S.; Rädler, J. O.; Wixforth, A.; Kostur, M.; Schindler, M.; Talkner, P.

    2004-11-01

    The flow profile in a capillary gap and the pumping efficiency of an acoustic micropump employing surface acoustic waves is investigated both experimentally and theoretically. Ultrasonic surface waves on a piezoelectric substrate strongly couple to a thin liquid layer and generate a quadrupolar streaming pattern within the fluid. We use fluorescence correlation spectroscopy and fluorescence microscopy as complementary tools to investigate the resulting flow profile. The velocity was found to depend on the applied power approximately linearly and to decrease with the inverse third power of the distance from the ultrasound generator on the chip. The found properties reveal acoustic streaming as a promising tool for the controlled agitation during microarray hybridization.

  9. Eco-friendly aqueous core surface-modified nanocapsules.

    Science.gov (United States)

    Carbone, C; Musumeci, T; Lauro, M R; Puglisi, G

    2015-01-01

    In this work, positively charged nanocapsules have been developed for potential ocular delivery exploiting the deposition of PLA onto the droplet surface of a W/O nanoemulsion prepared by the reversed procedure of the PIT method. PLA in combination with different amounts of various oils and surfactants have been studied in order to select the best formulation for polymeric nanocapsule preparation. The traditional visual observation together with the Turbiscan(®) technology were exploited in order to identify the best combination of polymer/oil for nanocapsule preparation. Two different primary surfactants (Span(®) 60 and Span(®) 80) have been tested to select their influence on the field of existence of the nanoemulsion by the construction of the pseudoternary phase diagrams. Cationic hybrid NC have been prepared by the addition of a coating layer of DDAB. The physico-chemical and morphological properties of all the prepared nanocapsules have been evaluated and compared by PCS, DSC and AFM. Therefore, positively charged nanocapsules can be easily prepared by a simple eco-friendly technique that exploits biocompatible materials avoiding a large input of mechanical energy as a potential ocular delivery systems for hydrophilic compounds or gene materials. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Biomolecular Nano-Flow-Sensor to Measure Near-Surface Flow

    Directory of Open Access Journals (Sweden)

    Noji Hiroyuki

    2009-01-01

    Full Text Available Abstract We have proposed and experimentally demonstrated that the measurement of the near-surface flow at the interface between a liquid and solid using a 10 nm-sized biomolecular motor of F1-ATPase as a nano-flow-sensor. For this purpose, we developed a microfluidic test-bed chip to precisely control the liquid flow acting on the F1-ATPase. In order to visualize the rotation of F1-ATPase, several hundreds nanometer-sized particle was immobilized at the rotational axis of F1-ATPase to enhance the rotation to be detected by optical microscopy. The rotational motion of F1-ATPase, which was immobilized on an inner surface of the test-bed chip, was measured to obtain the correlation between the near-surface flow and the rotation speed of F1-ATPase. As a result, we obtained the relationship that the rotation speed of F1-ATPase was linearly decelerated with increasing flow velocity. The mechanism of the correlation between the rotation speed and the near-surface flow remains unclear, however the concept to use biomolecule as a nano-flow-sensor was proofed successfully. (See supplementary material 1 Electronic supplementary material The online version of this article (doi:10.1007/s11671-009-9479-3 contains supplementary material, which is available to authorized users. Click here for file

  11. Vortices generation in the reactive flow on the evaporative surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Cha Ryeom; Lee, Chang Jin [Konkuk University, Seoul (Korea, Republic of)

    2015-02-15

    Vortices generation and flow dynamics are investigated by a numerical calculation with LES methodology on the evaporative surface including chemical reactions. For simplicity, fuel is radially injected from the surface in order to decouple pyrolysis of solid fuel from the governing equation and consideration of heat transfer balance. Nevertheless its simple treatment of chemical reactions and fuel pyrolysis, numerical results captured very fundamental understandings in terms of averaged temperature, velocity profile, and mixture fraction distribution. Results showed that a well-defined turbulent velocity profile at the inlet becomes twisted and highly wrinkled in the downstream reaching the maximum velocity at far above the surface, where the flame is located. And the thickness of boundary layer increases in the downstream due to the enhanced interaction of axial flow and mass injection from the surface. Also, chemical reaction appears highly active and partially concentrated along the plane where flow condition is in stoichiometric. In particular, flame front locates at the surface where mixture fraction Z equals to 0.07. Flame front severely wrinkles in the downstream by the interaction with turbulences in the flow. Partial reactions on the flame front contribute to produce hot spots periodically in the downstream attaining the max temperature at the center of each spot. This may take the role of additional unsteady heat generations and pressure perturbations in the downstream. Future study will focus on the evolution of hot spots and pressure perturbations in the post chamber of lab scale hybrid rocket motors.

  12. On the Existence of the Logarithmic Surface Layer in the Inner Core of Hurricanes

    Science.gov (United States)

    2012-01-01

    characteristics of eyewall boundary layer of Hurricane Hugo (1989). Mon. Wea. Rev., 139, 1447-1462. Zhang, JA, Montgomery MT. 2012 Observational...the inner core of hurricanes Roger K. Smitha ∗and Michael T. Montgomeryb a Meteorological Institute, University of Munich, Munich, Germany b Dept. of...logarithmic surface layer”, or log layer, in the boundary layer of the rapidly-rotating core of a hurricane . One such study argues that boundary-layer

  13. Flow profiling of a surface acoustic wave nanopump

    OpenAIRE

    Guttenberg, Z.; Rathgeber, A.; Keller, S.; Rädler, J. O.; Wixforth, A.; Kostur, M.; Schindler, M.; Talkner, P.

    2004-01-01

    The flow profile in a capillary gap and the pumping efficiency of an acoustic micropump employing Surface Acoustic Waves is investigated both experimentally and theoretically. Such ultrasonic surface waves on a piezoelectric substrate strongly couple to a thin liquid layer and generate an internal streaming within the fluid. Such acoustic streaming can be used for controlled agitation during, e.g., microarray hybridization. We use fluorescence correlation spectroscopy and fluorescence microsc...

  14. Surface core level shifts of clean and oxygen covered Ir(111)

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, M; Cassese, D; Cavallin, A; Comin, R; Orlando, F; Postregna, L [Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Golfetto, E; Baraldi, A [Dipartimento di Fisica e CENMAT, Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Lizzit, S [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste (Italy)], E-mail: alessandro.baraldi@elettra.trieste.it

    2009-06-15

    We present the results of high resolution core level photoelectron spectroscopy employed to investigate the electronic structure of clean and oxygen covered Ir(111) surface. Ir 4f{sub 7/2} core level spectra are shown to be very sensitive to the local atomic environment. For the clean surface we detected two distinct components shifted by 550 meV, originated by surface and bulk atoms. The larger Gaussian width of the bulk component is explained as due to experimentally unresolved subsurface components. In order to determine the relevance of the phonon contribution we examined the thermal behaviour of the core level lineshape using the Hedin-Rosengren theory. From the phonon-induced spectral broadening we found the Debye temperature of bulk and surface atoms to be 298 and 181 K, respectively, which confirms the softening of the vibrational modes at the surface. Oxygen adsorption leads to the appearance of new surface core level components at -200 meV and +230 meV, which are interpreted as due to first-layer Ir atoms differently coordinated with oxygen. The coverage dependence of these components demonstrates that the oxygen saturation corresponds to 0.38 ML, in good agreement with recent density functional theory calculations.

  15. Heat flow at the proposed Appalachian Ultradeep Core Hole (ADCOH) Site: Tectonic implications

    Science.gov (United States)

    Costain, John K.; Decker, Edward R.

    The heat flow in northwestern South Carolina at the Appalachian Ultradeep Core Hole (ADCOH) site area is approximately 55 mW/m². This data supplements other data to the east in the Piedmont and Atlantic Coastal Plain provinces where heat flows > 55 mW/m² are characteristic of post- and late-synmetamorphic granitoids. Piedmont heat flow and heat generation data for granites, metagranites, and one Slate Belt site, in a zone approximately parallel to major structural Appalachian trends, define a linear relation. Tectonic truncation of heat-producing crust at a depth of about 8 km (a depth equal to the slope of the heat flow-heat production line) is proposed to explain the linear relation. Using the value of reduced heat flow estimated from this empirical relation, and assuming thicknesses of heat-producing crust defined by new ADCOH seismic data, the heat flow and heat production at the ADCOH site are consistent with a depth to the base of the Inner Piedmont crystalline allochthon of about 5.5 km. Seismic data at the ADCOH site confirm that the Inner Piedmont is tectonically truncated at about 5.5 km by the Blue Ridge master decollement. Temperatures at 10 km at the ADCOH site are predicted to be less than 200 °C.

  16. Parametric study of flow patterns behind the standing accretion shock wave for core-collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Iwakami, Wakana; Nagakura, Hiroki [Yukawa Institute for Theoretical Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Yamada, Shoichi, E-mail: wakana@heap.phys.waseda.ac.jp [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555 (Japan)

    2014-05-10

    In this study, we conduct three-dimensional hydrodynamic simulations systematically to investigate the flow patterns behind the accretion shock waves that are commonly formed in the post-bounce phase of core-collapse supernovae. Adding small perturbations to spherically symmetric, steady, shocked accretion flows, we compute the subsequent evolutions to find what flow pattern emerges as a consequence of hydrodynamical instabilities such as convection and standing accretion shock instability for different neutrino luminosities and mass accretion rates. Depending on these two controlling parameters, various flow patterns are indeed realized. We classify them into three basic patterns and two intermediate ones; the former includes sloshing motion (SL), spiral motion (SP), and multiple buoyant bubble formation (BB); the latter consists of spiral motion with buoyant-bubble formation (SPB) and spiral motion with pulsationally changing rotational velocities (SPP). Although the post-shock flow is highly chaotic, there is a clear trend in the pattern realization. The sloshing and spiral motions tend to be dominant for high accretion rates and low neutrino luminosities, and multiple buoyant bubbles prevail for low accretion rates and high neutrino luminosities. It is interesting that the dominant pattern is not always identical between the semi-nonlinear and nonlinear phases near the critical luminosity; the intermediate cases are realized in the latter case. Running several simulations with different random perturbations, we confirm that the realization of flow pattern is robust in most cases.

  17. Mechanics of fluid flow over compliant wrinkled polymeric surfaces

    Science.gov (United States)

    Raayai, Shabnam; McKinley, Gareth; Boyce, Mary

    2014-03-01

    Skin friction coefficients (based on frontal area) of sharks and dolphins are lower than birds, fish and swimming beetles. By either exploiting flow-induced changes in their flexible skin or microscale textures, dolphins and sharks can change the structure of the fluid flow around them and thus reduce viscous drag forces on their bodies. Inspired by this ability, investigators have tried using compliant walls and riblet-like textures as drag reduction methods in aircraft and marine industries and have been able to achieve reductions up to 19%. Here we investigate flow-structure interaction and wrinkling of soft polymer surfaces that can emulate shark riblets and dolphin's flexible skin. Wrinkling arises spontaneously as the result of mismatched deformation of a thin stiff coating bound to a thick soft elastic substrate. Wrinkles can be fabricated by controlling the ratio of the stiffness of the coating and substrate, the applied displacement and the thickness of the coating. In this work we will examine the evolution in the kinematic structures associated with steady viscous flow over the polymer wrinkled surfaces and in particular compare the skin friction with corresponding results for flow over non-textured and rigid surfaces.

  18. Development of the test facilities for the measurement of core flow and pressure distribution of SMART reactor

    International Nuclear Information System (INIS)

    Ko, Y.J.; Euh, D.J.; Youn, Y.J.; Chu, I.C.; Kwon, T.S.

    2011-01-01

    A design of SMART reactor has been developed, of which the primary system is composed of four internal circulation pumps, a core of 57 fuel assemblies, eight cassettes of steam generators, flow mixing head assemblies, and other internal structures. Since primary design features are very different from conventional reactors, the characteristics of flow and pressure distribution are expected to be different accordingly. In order to analyze the thermal margin and hydraulic design characteristics of SMART reactor, design quantification tests for flow and pressure distribution with a preservation of flow geometry are necessary. In the present study, the design feature of the test facility in order to investigate flow and pressure distribution, named “SCOP” is described. In order to preserve the flow distribution characteristics, the SCOP is linearly reduced with a scaling ratio of 1/5. The core flow rate of each fuel assembly is measured by a venturi meter attached in the lower part of the core simulator having a similarity of pressure drop for nominally scaled flow conditions. All the 57 core simulators and 8 S/G simulators are precisely calibrated in advance of assembling in test facilities. The major parameters in tests are pressures, differential pressures, and core flow distribution. (author)

  19. Moving least squares simulation of free surface flows

    DEFF Research Database (Denmark)

    Felter, C. L.; Walther, Jens Honore; Henriksen, Christian

    2014-01-01

    In this paper a Moving Least Squares method (MLS) for the simulation of 2D free surface flows is presented. The emphasis is on the governing equations, the boundary conditions, and the numerical implementation. The compressible viscous isothermal Navier–Stokes equations are taken as the starting ...

  20. Numerical simulations of viscoelastic flows with free surfaces

    DEFF Research Database (Denmark)

    Comminal, Raphaël; Spangenberg, Jon; Hattel, Jesper Henri

    2013-01-01

    We present a new methodology to simulate viscoelastic flows with free-surfaces. These simulations are motivated by the modelling of polymers manufacturing techniques, such as extrusion and injection moulding. One of the consequences of viscoelasticity is that polymeric materials have a “memory...

  1. Nitrogen Transformation and Removal in Horizontal Surface Flow ...

    African Journals Online (AJOL)

    The potential use of Constructed Mangrove Wetlands (CMWs) as a cheaper, effective and appropriate method for Nitrogen removal from domestic sewage of coastal zone in peri-urban cities was investigated from August 2007 to. September, 2008. Field investigations were made on horizontal surface flow constructed ...

  2. A surface-renewal model of cross-flow microfiltration

    Directory of Open Access Journals (Sweden)

    A. Hasan

    2013-03-01

    Full Text Available A mathematical model using classical cake-filtration theory and the surface-renewal concept is formulated for describing cross-flow microfiltration under dynamic and steady-state conditions. The model can predict the permeate flux and cake buildup in the filter. The three basic parameters of the model are the membrane resistance, specific cake resistance and rate of surface renewal. The model is able to correlate experimental permeate flow rate data in the microfiltration of fermentation broths in laboratory- and pilot-scale units with an average root-mean-square (RMS error of 4.6%. The experimental data are also compared against the critical-flux model of cross-flow microfiltration, which has average RMS errors of 6.3, 5.5 and 6.1% for the cases of cake filtration, intermediate blocking and complete blocking mechanisms, respectively.

  3. Benthic foraminiferal census data from Mobile Bay, Alabama--counts of surface samples and box cores

    Science.gov (United States)

    Richwine, Kathryn A.; Osterman, Lisa E.

    2012-01-01

    A study was undertaken in order to understand recent environmental change in Mobile Bay, Alabama. For this study a series of surface sediment and box core samples was collected. The surface benthic foraminiferal data provide the modern baseline conditions of the bay and can be used as a reference for changing paleoenvironmental parameters recorded in the box cores. The 14 sampling locations were chosen in the bay to cover the wide diversity of fluvial and marine-influenced environments on both sides of the shipping channel.

  4. Measurement of the complete core plasma flow across the LOC-SOC transition at ASDEX Upgrade

    Science.gov (United States)

    Lebschy, A.; McDermott, R. M.; Angioni, C.; Geiger, B.; Prisiazhniuk, D.; Cavedon, M.; Conway, G. D.; Dux, R.; Dunne, M. G.; Kappatou, A.; Pütterich, T.; Stroth, U.; Viezzer, E.; the ASDEX Upgrade Team

    2018-02-01

    A newly installed core charge exchange recombination spectroscopy (CXRS) diagnostic at ASDEX Upgrade (AUG) enables the evaluation of the core poloidal rotation (upol ) through the inboard-outboard asymmetry of the toroidal rotation with an accuracy of 0.5 to 1 km s-1 . Using this technique, the total plasma flow has been measured in Ohmic L-mode plasmas across the transition from the linear to saturated ohmic confinement (LOC-SOC) regimes. The core poloidal rotation of the plasma around mid-radius is found to be always in the ion diamagnetic direction, in disagreement with neoclassical (NC) predictions. The edge rotation is found to be electron-directed and consistent with NC codes. This measurement provides as well the missing ingredient to evaluate the core E×B velocity (uE×B ) from data only, which can then be compared to measurements of the perpendicular velocity of the turbulent fluctuations (u\\perp ) to gain information on the turbulent phase velocity (vph ). The non neoclassical upol from CXRS leads to good agreement between uE×B and u\\perp indicating that vph is small and at similar values as found with gyrokinetic simulations. Moreover, the data shows a shift of vph in the ion-diamagnetic direction at the edge after the transition from LOC to SOC consistent with a change in the dominant turbulence regime. The upgrade of the core CXRS system provides as well a deeper insight into the intrinsic rotation. This paper shows that the reversal of the core toroidal rotation occurs clearly after the LOC-SOC transition and concomitant with the peaking of the electron density.

  5. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    State-of-the-art in network coding for wireless, meshed networks typically considers two problems separately. First, the problem of providing reliability for a single session. Second, the problem of opportunistic combination of flows by using minimalistic coding, i.e., by XORing packets from diff...

  6. Integral methods for shallow free-surface flows with separation

    DEFF Research Database (Denmark)

    Watanabe, S.; Putkaradze, V.; Bohr, Tomas

    2003-01-01

    eddy and separated flow. Assuming a variable radial velocity profile as in Karman-Pohlhausen's method, we obtain a system of two ordinary differential equations for stationary states that can smoothly go through the jump. Solutions of the system are in good agreement with experiments. For the flow down...... an inclined plane we take a similar approach and derive a simple model in which the velocity profile is not restricted to a parabolic or self-similar form. Two types of solutions with large surface distortions are found: solitary, kink-like propagating fronts, obtained when the flow rate is suddenly changed......, and stationary jumps, obtained, for instance, behind a sluice gate. We then include time dependence in the model to study the stability of these waves. This allows us to distinguish between sub- and supercritical flows by calculating dispersion relations for wavelengths of the order of the width of the layer....

  7. Incompressible flows of superfluid films on multiply-connected surfaces

    International Nuclear Information System (INIS)

    Corrada-Emmanuel, A.

    1989-01-01

    The theory of Riemann surfaces is applied to the problem of constructing quantized vortex flows in closed surfaces of arbitrary but finite genus. An in principle procedure for obtaining the lowest energy flow is presented. It is shown that quantized vortices in non-zero genus surfaces are, in general, not isomorphic to a Coulomb gas. This failure has a geometrical origin: the appearance in non-zero genus surfaces of closed curves that are not the boundary of any area. A theorem of Riemann is applied to the genus one surface, the torus, to show quantitatively how to construct the quantized vortices. Because of the breakdown in the isomorphism between quantized vortices and charges, a novel effect is possible: the violation of Earnshaw's theorem. On a torus a single vortex can be placed in local stable equilibrium. The uniform flows around the holes of the torus also lead to a new result: a non-vortex mechanism for the destruction of superfluidity in the film. An explicit formula is derived showing this effect by considering the response of a helium film to a rotation of the torus. The author predicts that torii of dissimilar proportions will exhibit different superfluid densities at the same temperature

  8. VALIDATION OF NUMERICAL METHODS TO CALCULATE BYPASS FLOW IN A PRISMATIC GAS-COOLED REACTOR CORE

    Directory of Open Access Journals (Sweden)

    NAM-IL TAK

    2013-11-01

    Full Text Available For thermo-fluid and safety analyses of a High Temperature Gas-cooled Reactor (HTGR, intensive efforts are in progress in the developments of the GAMMA+ code of Korea Atomic Energy Research Institute (KAERI and the AGREE code of the University of Michigan (U of M. One of the important requirements for GAMMA+ and AGREE is an accurate modeling capability of a bypass flow in a prismatic core. Recently, a series of air experiments were performed at Seoul National University (SNU in order to understand bypass flow behavior and generate an experimental database for the validation of computer codes. The main objective of the present work is to validate the GAMMA+ and AGREE codes using the experimental data published by SNU. The numerical results of the two codes were compared with the measured data. A good agreement was found between the calculations and the measurement. It was concluded that GAMMA+ and AGREE can reliably simulate the bypass flow behavior in a prismatic core.

  9. Ring waves as a mass transport mechanism in air-driven core-annular flows.

    Science.gov (United States)

    Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

    2012-12-01

    Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

  10. Experimental investigation of the vibration response of a flexible tube due to simulated reactor core, cross and annular exit flows

    International Nuclear Information System (INIS)

    Haslinger, K.H.; Martin, M.L.; Higgins, W.H.; Rossano, F.V.

    1989-01-01

    Instrumentation tubes in pressurized nuclear reactors have experienced wear due to excessive flow-induced vibrations. Experiments to identify the predominant flow excitation mechanism at a particular plant, and to develop a sleeve design to remedy the wear problem are reported. An instrumented flow visualization model enabled simulation of a wide range of individual or combined reactor core flow, cross flow and thimble flow conditions. The instrumentation scheme adopted for these experiments used proximity displacement transducers and a force transducer to measure respectively tube motion and contact/impact forces at the wear region. Extensive testing of the original, in-plant configuration identified the normal core flow as the primary source of excitation. Shielding the In-Core-Instrumentation thimble tube from the normal core flow curtailed vibration amplitudes; however, thimble flow excitation then became more pronounced. Various outlet nozzle configurations were investigated. An internal cavity combined with radial outlet slots became the optimum solution for the problem. The paper presents typical test data in the form of orbital tube motion, spectrum analysis and time history collages. The effectiveness of shielding the instrumentation tube from the flow is demonstrated. (author)

  11. CURVATURE-DRIVEN MOLECULAR FLOW ON MEMBRANE SURFACE.

    Science.gov (United States)

    Mikucki, Michael; Zhou, Y C

    2017-01-01

    This work presents a mathematical model for the localization of multiple species of diffusion molecules on membrane surfaces. Morphological change of bilayer membrane in vivo is generally modulated by proteins. Most of these modulations are associated with the localization of related proteins in the crowded lipid environments. We start with the energetic description of the distributions of molecules on curved membrane surface, and define the spontaneous curvature of bilayer membrane as a function of the molecule concentrations on membrane surfaces. A drift-diffusion equation governs the gradient flow of the surface molecule concentrations. We recast the energetic formulation and the related governing equations by using an Eulerian phase field description to define membrane morphology. Computational simulations with the proposed mathematical model and related numerical techniques predict (i) the molecular localization on static membrane surfaces at locations with preferred mean curvatures, and (ii) the generation of preferred mean curvature which in turn drives the molecular localization.

  12. Investigation of aluminum surface cleaning using cavitating fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Ralys, Aurimas; Striška, Vytautas; Mokšin, Vadim [Vilnius Gediminas Technical University, Faculty of Mechanics, Department of Machine Engineering, J. Basanavičiaus str.28, 03224, Vilnius (Lithuania)

    2013-12-16

    This paper investigates efficiency of specially designed atomizer used to spray water and cavitate microbubbles in water flow. Surface cleaning system was used to clean machined (grinded) aluminum surface from abrasive particles. It is established that cleaning efficiency depends on diameter of the diffuser, water pressure and distance between nozzle and metal surface. It is obtained that the best cleaning efficiency (100%) is achieved at pressure 36 bar, when diameter of diffuser is 0.4 mm and distance between nozzle and surface is 1 mm. It is also established that satisfactory cleaning efficiency (80%) is achieved not only when atomizer is placed closer to metal surface, but also at larger (120 mm) distances.

  13. Spatial characteristics of secondary flow in a turbulent boundary layer over longitudinal surface roughness

    Science.gov (United States)

    Hwang, Hyeon Gyu; Lee, Jae Hwa

    2017-11-01

    Direct numerical simulations of turbulent boundary layers (TBLs) over spanwise heterogeneous surface roughness are performed to investigate the characteristics of secondary flow. The longitudinal surface roughness, which features lateral change in bed elevation, is described by immersed boundary method. The Reynolds number based on the momentum thickness is varied in the range of Reθ = 300-900. As the TBLs over the roughness elements spatially develop in the streamwise direction, a secondary flow emerges in a form of counter-rotating vortex pair. As the spanwise spacing between the roughness elements and roughness width vary, it is shown that the size of the secondary flow is determined by the valley width between the roughness elements. In addition, the strength of the secondary flow is mostly affected by the spanwise distance between the cores of the secondary flow. Analysis of the Reynolds-averaged turbulent kinetic energy transport equation reveals that the energy redistribution terms in the TBLs over-the ridge type roughness play an important role to derive low-momentum pathways with upward motion over the roughness crest, contrary to the previous observation with the strip-type 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).

  14. Mathematical modelling of powder material motion and transportation in high-temperature flow core during plasma coatings application

    Science.gov (United States)

    Bogdanovich, V. I.; Giorbelidze, M. G.

    2018-03-01

    A problem of mathematical modelling of powder material motion and transportation in gas thermal flow core has been addressed. Undertaken studies indicate significant impact on dynamics of motion of sprayed particles of phenomenological law for drag coefficient and accounting momentum loss of a plasma jet upon acceleration of these particles and their diameter. It is determined that at great dispersion of spraying particles, they reach detail surface at different velocity and significant particles separation takes place at spraying spot. According to the results of mathematical modelling, requirements for admissible dispersion of diameters of particles used for spraying have been formulated. Research has also allowed reducing separation of particles at the spraying spot due to the selection of the method of powder feed to the anode channel of the plasma torch.

  15. Core microstructure, morphology and chain arrangement of block copolymer self-assemblies as investigated by thermal field-flow fractionation.

    Science.gov (United States)

    Muza, U L; Greyling, G; Pasch, H

    2018-05-28

    The self-assembly of block copolymers (BCPs), as a result of solvent selectivity for one block, has recently received significant attention due to novel applications of BCPs in pharmaceuticals, biomedicine, cosmetics, electronics and nanotechnology. The correlation of BCP microstructure and the structure of the resulting self-assemblies requires advanced analytical methods. However, traditional bulk characterization techniques are limited in the quest of providing detailed information regarding molar mass (M w ), hydrodynamic size (D h ), chemical composition, and morphology for these self-assemblies. In the present study, thermal field-flow fractionation (ThFFF) is utilised to investigate the impact of core microstructure on the resultant solution properties of vesicles prepared from polystyrene-polybutadiene block copolymers (PS-b-PBd) with 1.2- and 1.4-polybutadiene blocks, respectively. As compared to investigations on the impact of the corona microstructure, the impact of core microstructure on micellar properties has largely been neglected in previous work. In N,N-dimethylacetamide (DMAc) these BCPs form vesicles having PS shells and PBd cores. D h , M w , aggregation number, and critical micelle concentration of these micelles are shown to be sensitive to the core microstructure, therefore, demonstrating the potential of microstructural differences to be used for providing tuneable pathways to specific self-assemblies. It is shown that micelles prepared from BCPs of similar PS and PBd block sizes are successfully separated by ThFFF. It is further demonstrated in this study that PS-b-PBd vesicles and PS homopolymers of identical surface chemistry (PS) and comparable D h in DMAc, can be separated by ThFFF. Copyright © 2018. Published by Elsevier B.V.

  16. Analysis of resonance oscillation of the neutron flow in a BWR-core

    International Nuclear Information System (INIS)

    Storm, J.

    1987-09-01

    This is a thesis which has been made within the institution of automatic control in Lund. Two programs, 'Blackie' and 'Test' have been written in Fortran. These two programs are to be used for the evaluation of ASEA-ATOMs resonance test in different nuclear reactors. In these tests the condition of the reactor becomes more and more unstable because the coolant flow decreases at the same time as the power gradually increases. This leads to resonance in the neutron flow. This flow is measured by detectors placed in different parts of the reactor core. 'Blackie' receives and stores the values sampled by the detectors. The same program also carries out a Fourier analysis. Amplitudes and phase angles from the different oscillations are calculated. These results are then used as inputs for 'Test'. 'Test' is a plotting program. It draws the reactor and plots arrows where the detectors are situated. The size and direction of the arrows are measurements of the amplitudes and phase angles of the neutron flow oscillations. From these arrow diagrams you can come to conclusions about the oscillations in the neutron flow and how the affect the reactor. (author)

  17. The effect of carbon nanotube chirality on the spiral flow of copper atoms in their cores

    International Nuclear Information System (INIS)

    Lim, M.C.G.; Zhong, Z.W.

    2012-01-01

    The effect of carbon nanotube (CNT) chirality on the flow of copper atoms along its core has been investigated using molecular dynamics simulations. The investigation is conducted using CNTs of different chirality, and different flow conditions such as temperatures, bias voltages and the initial positions of the copper atoms. The results show that the atoms flow in a spiral fashion along the CNT channels. The effect is most evident in the CNT channel with zigzag CNTs. The movement of the copper atoms is more erratic when the temperature is increased at a low biased voltage, regardless of the types of channel used. The initial positions of the copper atoms affect the way they converge as they move downstream along the channel. A bias voltage of 4 V favours the initiation of a spiral flow, especially when the position of the copper atoms is far from the central axis of the channel. -- Highlights: ► We model the transportation of copper atoms in armchair and zigzag CNT channels. ► The spiral flow of copper atoms occurs in a semiconductor–semiconductor CNT. ► The compact copper mass is predicted to occur at 673 K with a 4 V bias voltage.

  18. A new model for turbidity current behavior based on integration of flow monitoring and precision coring in a submarine canyon

    Science.gov (United States)

    Symons, William O.; Sumner, Esther J.; Paull, Charles K.; Cartigny, Matthieu J.B.; Xu, Jingping; Maier, Katherine L.; Lorenson, Thomas; Talling, Peter J.

    2017-01-01

    Submarine turbidity currents create some of the largest sediment accumulations on Earth, yet there are few direct measurements of these flows. Instead, most of our understanding of turbidity currents results from analyzing their deposits in the sedimentary record. However, the lack of direct flow measurements means that there is considerable debate regarding how to interpret flow properties from ancient deposits. This novel study combines detailed flow monitoring with unusually precisely located cores at different heights, and multiple locations, within the Monterey submarine canyon, offshore California, USA. Dating demonstrates that the cores include the time interval that flows were monitored in the canyon, albeit individual layers cannot be tied to specific flows. There is good correlation between grain sizes collected by traps within the flow and grain sizes measured in cores from similar heights on the canyon walls. Synthesis of flow and deposit data suggests that turbidity currents sourced from the upper reaches of Monterey Canyon comprise three flow phases. Initially, a thin (38–50 m) powerful flow in the upper canyon can transport, tilt, and break the most proximal moorings and deposit chaotic sands and gravel on the canyon floor. The initially thin flow front then thickens and deposits interbedded sands and silty muds on the canyon walls as much as 62 m above the canyon floor. Finally, the flow thickens along its length, thus lofting silty mud and depositing it at greater altitudes than the previous deposits and in excess of 70 m altitude.

  19. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  20. Aerobic and Anaerobic Bacterial Isolates on the Surface and Core of Tonsils from Patients with Chronic Tonsillitis

    Directory of Open Access Journals (Sweden)

    Meera Niranjan Khadilkar

    2017-08-01

    Full Text Available Introduction Controversy regarding treatment of tonsillitis based on throat culture report still persists. If surface culture is a determinant of bacteriology of the core, then rational therapy could be aimed at organisms cultured by surface swab. Materials and Methods A Cross-sectional study was conducted on 100 patients of chronic tonsillitis who underwent tonsillectomy. Tonsil surface and core swabs were studied for aerobic and anaerobic growth. Result Eighty seven percent patients had aerobic growth on tonsil surface and ninety percent in tonsil core. Staphylococcus aureus was the commonest aerobic bacteria isolated. Anaerobic growth was present in 47% patients on tonsil surface, and 48% in core. Porphyromonas sp. was the commonest anaerobic bacterium isolated. Discussion There was no statistically significant difference between aerobic and anaerobic bacteria found in tonsil surface and core.  Conclusion Throat swabs adequately represent core pathogen, and are dependable in detecting bacteriology of chronic tonsillitis.

  1. Interaction of sigma 70 with Escherichia coli RNA polymerase core enzyme studied by surface plasmon resonance.

    Science.gov (United States)

    Ferguson, A L; Hughes, A D; Tufail, U; Baumann, C G; Scott, D J; Hoggett, J G

    2000-09-22

    The interaction between the core form of bacterial RNA polymerases and sigma factors is essential for specific promoter recognition, and for coordinating the expression of different sets of genes in response to varying cellular needs. The interaction between Escherichia coli core RNA polymerase and sigma 70 has been investigated by surface plasmon resonance. The His-tagged form of sigma 70 factor was immobilised on a Ni2+-NTA chip for monitoring its interaction with core polymerase. The binding constant for the interaction was found to be 1.9x10(-7) M, and the dissociation rate constant for release of sigma from core, in the absence of DNA or transcription, was 4x10(-3) s(-1), corresponding to a half-life of about 200 s.

  2. Characterizing developing adverse pressure gradient flows subject to surface roughness

    Science.gov (United States)

    Brzek, Brian; Chao, Donald; Turan, Özden; Castillo, Luciano

    2010-04-01

    An experimental study was conducted to examine the effects of surface roughness and adverse pressure gradient (APG) on the development of a turbulent boundary layer. Hot-wire anemometry measurements were carried out using single and X-wire probes in all regions of a developing APG flow in an open return wind tunnel test section. The same experimental conditions (i.e., T ∞, U ref, and C p) were maintained for smooth, k + = 0, and rough, k + = 41-60, surfaces with Reynolds number based on momentum thickness, 3,000 carefully designed such that the x-dependence in the flow field was known. Despite this fact, only a very small region of the boundary layer showed a balance of the various terms in the integrated boundary layer equation. The skin friction computed from this technique showed up to a 58% increase due to the surface roughness. Various equilibrium parameters were studied and the effect of roughness was investigated. The generated flow was not in equilibrium according to the Clauser (J Aero Sci 21:91-108, 1954) definition due to its developing nature. After a development region, the flow reached the equilibrium condition as defined by Castillo and George (2001), where Λ = const, is the pressure gradient parameter. Moreover, it was found that this equilibrium condition can be used to classify developing APG flows. Furthermore, the Zagarola and Smits (J Fluid Mech 373:33-79, 1998a) scaling of the mean velocity deficit, U ∞δ*/δ, can also be used as a criteria to classify developing APG flows which supports the equilibrium condition of Castillo and George (2001). With this information a ‘full APG region’ was defined.

  3. Free surface flow with moving rigid bodies. Part 1. Computational flow model

    International Nuclear Information System (INIS)

    Gubanov, O.I.; Mironova, L.A.; Kocabiyik, S.

    2005-01-01

    This paper was motivated by the study of Hirt and Sicilian, where the 'differential form' of the governing equations for the inviscid fluid flow (FAVOR equations) were obtained. We utilize mainly generalized differentiation to extend the Reynolds transport theorem over a control volume containing fluid interface for deriving the 'integral form' of governing equations for the incompressible viscous flow problems. This is done following the work by Farassat and the use of generalized function theory made this derivation straightforward, systematic and rigorous. The resulting equations are discretized by a finite-volume method using a staggered grid, after making use of the coarse-scale approximation. The resulting governing equations are valid for a class of flows including free surface flows with arbitrarily moving bodies and are consistent with Hirt and Sicilian's formulation in the inviscid fluid flow case. (author)

  4. Flow Boiling on a Downward-Facing Inclined Plane Wall of Core Catcher

    International Nuclear Information System (INIS)

    Kim, Hyoung Tak; Bang, Kwang Hyun; Suh, Jung Soo

    2013-01-01

    In order to investigate boiling behavior on downward-facing inclined heated wall prior to the CHF condition, an experiment was carried out with 1.2 m long rectangular channel, inclined by 10 .deg. from the horizontal plane. High speed video images showed that the bubbles were sliding along the heated wall, continuing to grow and combining with the bubbles growing at their nucleation sites in the downstream. These large bubbles continued to slide along the heated wall and formed elongated slug bubbles. Under this slug bubble thin liquid film layer on the heated wall was observed and this liquid film prevents the wall from dryout. The length, velocity and frequency of slug bubbles sliding on the heated wall were measured as a function of wall heat flux and these parameters were used to develop wall boiling model for inclined, downward-facing heated wall. One approach to achieve coolable state of molten core in a PWR-like reactor cavity during a severe accident is to retain the core melt on a so-called core catcher residing on the reactor cavity floor after its relocation from the reactor pressure vessel. The core melt retained in the core catcher is cooled by water coolant flowing in an inclined cooling channel underneath as well as the water pool overlaid on the melt layer. Two-phase flow boiling with downward-facing heated wall such as this core catcher cooling channel has drawn a special attention because this orientation of heated wall may reach boiling crisis at lower heat flux than that of a vertical or upward-facing heated wall. Nishikawa and Fujita, Howard and Mudawar, Qiu and Dhir have conducted experiments to study the effect of heater orientation on boiling heat transfer and CHF. SULTAN experiment was conducted to study inclined large-scale structure coolability by water in boiling natural convection. In this paper, high-speed visualization of boiling behavior on downward-facing heated wall inclined by 10 .deg. is presented and wall boiling model for the

  5. Characterization of interfacial waves and pressure drop in horizontal oil-water core-annular flows

    Science.gov (United States)

    Tripathi, Sumit; Tabor, Rico F.; Singh, Ramesh; Bhattacharya, Amitabh

    2017-08-01

    We study the transportation of highly viscous furnace-oil in a horizontal pipe as core-annular flow (CAF) using experiments. Pressure drop and high-speed images of the fully developed CAF are recorded for a wide range of flow rate combinations. The height profiles (with respect to the centerline of the pipe) of the upper and lower interfaces of the core are obtained using a high-speed camera and image analysis. Time series of the interface height are used to calculate the average holdup of the oil phase, speed of the interface, and the power spectra of the interface profile. We find that the ratio of the effective velocity of the annular fluid to the core velocity, α , shows a large scatter. Using the average value of this ratio (α =0.74 ) yields a good estimate of the measured holdup for the whole range of flow rate ratios, mainly due to the low sensitivity of the holdup ratio to the velocity ratio. Dimensional analysis implies that, if the thickness of the annular fluid is much smaller than the pipe radius, then, for the given range of parameters in our experiments, the non-dimensional interface shape, as well as the non-dimensional wall shear stress, can depend only on the shear Reynolds number and the velocity ratio. Our experimental data show that, for both lower and upper interfaces, the normalized power spectrum of the interface height has a strong dependence on the shear Reynolds number. Specifically, for low shear Reynolds numbers, interfacial modes with large wavelengths dominate, while, for large shear Reynolds numbers, interfacial modes with small wavelengths dominate. Normalized variance of the interface height is higher at lower shear Reynolds numbers and tends to a constant with increasing shear Reynolds number. Surprisingly, our experimental data also show that the effective wall shear stress is, to a large extent, proportional to the square of the core velocity. Using the implied scalings for the holdup ratio and wall shear stress, we can derive

  6. Ultrasonic density detector for vessel and reactor core two-phase flow measurements

    International Nuclear Information System (INIS)

    Arave, A.E.

    1979-01-01

    A local ultrasonic density (LUD) detector has been developed by EG and G Idaho, Inc., at the Idaho National Engineering Laboratory for the Loss-of-Fluid Test (LOFT) reactor vessel and core two-phase flow density measurements. The principle of operating the sensor is the change in propagation time of a torsional ultrasonic wave in a metal transmission line as a function of the density of the surrounding media. A theoretical physics model is presented which represents the total propagation time as a function of the sensor modulus of elasticity and polar moment of inertia

  7. Thermal-hydraulic analysis of PWR core including intermediate flow mixers with the THYC code

    International Nuclear Information System (INIS)

    Mur, J.; Meignin, J.C.

    1997-07-01

    Departure from nucleate boiling (DNB) is one of the major limiting factors of pressurized water reactors (PWRs). Safety requires that occurrence of DNB should be precluded under normal or incidental operating conditions. The thermal-hydraulic THYC code developed by EDF is described. The code is devoted to heat and mass transfer in nuclear components. Critical Heat Flux (CHF) is predicted from local thermal-hydraulic parameters such as pressure, mass flow rate, and quality. A three stage methodology to evaluate thermal margins in order to perform standard core design is described. (K.A.)

  8. Thermal-hydraulic analysis of PWR core including intermediate flow mixers with the THYC code

    Energy Technology Data Exchange (ETDEWEB)

    Mur, J. [Electricite de France (EDF), 78 - Chatou (France); Meignin, J.C. [Electricite de France (EDF), 69 - Villeurbanne (France)

    1997-07-01

    Departure from nucleate boiling (DNB) is one of the major limiting factors of pressurized water reactors (PWRs). Safety requires that occurrence of DNB should be precluded under normal or incidental operating conditions. The thermal-hydraulic THYC code developed by EDF is described. The code is devoted to heat and mass transfer in nuclear components. Critical Heat Flux (CHF) is predicted from local thermal-hydraulic parameters such as pressure, mass flow rate, and quality. A three stage methodology to evaluate thermal margins in order to perform standard core design is described. (K.A.) 8 refs.

  9. New sol–gel refractory coatings on chemically-bonded sand cores for foundry applications to improve casting surface quality

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Poulsen, T.; Stage, R.K.

    2011-01-01

    Foundry refractory coatings protect bonded sand cores and moulds from producing defective castings during the casting process by providing a barrier between the core and the liquid metal. In this study, new sol–gel refractory coating on phenolic urethane cold box (PUCB) core was examined. The coa......Foundry refractory coatings protect bonded sand cores and moulds from producing defective castings during the casting process by providing a barrier between the core and the liquid metal. In this study, new sol–gel refractory coating on phenolic urethane cold box (PUCB) core was examined......–gel coated cores have better surface quality than those from uncoated cores and comparable surface quality with the commercial coatings. Therefore, the new sol–gel coating has a potential application in the foundry industry for improving the surface finish of castings thereby reducing the cost of fettling...

  10. Characterization of groundwater flow for near surface disposal facilities

    International Nuclear Information System (INIS)

    2001-02-01

    The main objective of this report is to provide a description of the site investigation techniques and modelling approaches that can be used to characterise the flow of subsurface water at near surface disposal facilities in relation to the various development stages of the repositories. As one of the main goals of defining groundwater flow is to establish the possible contaminant migration, certain aspects related to groundwater transport are also described. Secondary objectives are to discuss the implications of various groundwater conditions with regard to the performance of the isolation systems

  11. Asteroseismic measurement of surface-to-core rotation in a main-sequence star*

    Directory of Open Access Journals (Sweden)

    Kurtz Donald W.

    2015-01-01

    Full Text Available We have discovered rotationally split core g-mode triplets and surface p-mode triplets and quintuplets in a terminal age main-sequence A star, KIC 11145123, that shows both δ Sct p-mode pulsations and γ Dor g-mode pulsations. This gives the first robust determination of the rotation of the deep core and surface of a main-sequence star, essentially model-independently. We find its rotation to be nearly uniform with a period near 100 d, but we show with high confidence that the surface rotates slightly faster than the core. A strong angular momentum transfer mechanism must be operating to produce the nearly rigid rotation, and a mechanism other than viscosity must be operating to produce a more rapidly rotating surface than core. Our asteroseismic result, along with previous asteroseismic constraints on internal rotation in some B stars, and measurements of internal rotation in some subgiant, giant and white dwarf stars, has made angular momentum transport in stars throughout their lifetimes an observational science.

  12. Preparation and recognition of surface molecularly imprinted core-shell microbeads for protein in aqueous solutions

    International Nuclear Information System (INIS)

    Lu Yan; Yan Changling; Gao Shuyan

    2009-01-01

    In this paper, a surface molecular imprinting technique was reported for preparing core-shell microbeads of protein imprinting, and bovine hemoglobin or bovine serum albumin were used as model proteins for studying the imprinted core-shell microbeads. 3-Aminophenylboronic acid (APBA) was polymerized onto the surface of polystyrene microbead in the presence of the protein templates to create protein-imprinted core-shell microbeads. The various samples were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) methods. The effect of pH on rebinding of the template hemoglobin, the specific binding and selective recognition were studied for the imprinted microbeads. The results show that the bovine hemoglobin-imprinted core-shell microbeads were successfully created. The shell was a sort of imprinted thin films with porous structure and larger surface areas. The imprinted microbeads have good selectivity for templates and high stability. Due to the recognition sites locating at or closing to the surface, these imprinted microbeads have good property of mass-transport. Unfortunately, the imprint technology was not successfully applied to imprinting bovine serum albumin (BSA).

  13. Preparation and recognition of surface molecularly imprinted core-shell microbeads for protein in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yan, E-mail: yanlu2001@sohu.com [College of Chemistry and Environmental Science, Henan Normal University, 46 Jlanshe Road, Xinxiang 453007 (China); Yan Changling; Gao Shuyan [College of Chemistry and Environmental Science, Henan Normal University, 46 Jlanshe Road, Xinxiang 453007 (China)

    2009-04-01

    In this paper, a surface molecular imprinting technique was reported for preparing core-shell microbeads of protein imprinting, and bovine hemoglobin or bovine serum albumin were used as model proteins for studying the imprinted core-shell microbeads. 3-Aminophenylboronic acid (APBA) was polymerized onto the surface of polystyrene microbead in the presence of the protein templates to create protein-imprinted core-shell microbeads. The various samples were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) methods. The effect of pH on rebinding of the template hemoglobin, the specific binding and selective recognition were studied for the imprinted microbeads. The results show that the bovine hemoglobin-imprinted core-shell microbeads were successfully created. The shell was a sort of imprinted thin films with porous structure and larger surface areas. The imprinted microbeads have good selectivity for templates and high stability. Due to the recognition sites locating at or closing to the surface, these imprinted microbeads have good property of mass-transport. Unfortunately, the imprint technology was not successfully applied to imprinting bovine serum albumin (BSA).

  14. Surface and Flow Field Measurements on the FAITH Hill Model

    Science.gov (United States)

    Bell, James H.; Heineck, James T.; Zilliac, Gregory; Mehta, Rabindra D.; Long, Kurtis R.

    2012-01-01

    A series of experimental tests, using both qualitative and quantitative techniques, were conducted to characterize both surface and off-surface flow characteristics of an axisymmetric, modified-cosine-shaped, wall-mounted hill named "FAITH" (Fundamental Aero Investigates The Hill). Two separate models were employed: a 6" high, 18" base diameter machined aluminum model that was used for wind tunnel tests and a smaller scale (2" high, 6" base diameter) sintered nylon version that was used in the water channel facility. Wind tunnel and water channel tests were conducted at mean test section speeds of 165 fps (Reynolds Number based on height = 500,000) and 0.1 fps (Reynolds Number of 1000), respectively. The ratio of model height to boundary later height was approximately 3 for both tests. Qualitative techniques that were employed to characterize the complex flow included surface oil flow visualization for the wind tunnel tests, and dye injection for the water channel tests. Quantitative techniques that were employed to characterize the flow included Cobra Probe to determine point-wise steady and unsteady 3D velocities, Particle Image Velocimetry (PIV) to determine 3D velocities and turbulence statistics along specified planes, Pressure Sensitive Paint (PSP) to determine mean surface pressures, and Fringe Imaging Skin Friction (FISF) to determine surface skin friction (magnitude and direction). This initial report summarizes the experimental set-up, techniques used, data acquired and describes some details of the dataset that is being constructed for use by other researchers, especially the CFD community. Subsequent reports will discuss the data and their interpretation in more detail

  15. Production circulator fabrication and testing for core flow test loop. Final report, Phase III

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    The performance testing of two production helium circulators utilizing gas film lubrication is described. These two centrifugal-type circulators plus an identical circulator prototype will be arranged in series to provide the helium flow requirements for the Core Flow Test Loop which is part of the Gas-Cooled Fast Breeder Reactor Program (GCFR) at the Oak Ridge National Laboratory. This report presents the results of the Phase III performance and supplemental tests, which were carried out by MTI during the period of December 18, 1980 through March 19, 1981. Specific test procedures are outlined and described, as are individual tests for measuring the performance of the circulators. Test data and run descriptions are presented.

  16. NASA Glenn Research Center, Propulsion Systems Laboratory: Plan to Measure Engine Core Flow Water Vapor Content

    Science.gov (United States)

    Oliver, Michael

    2014-01-01

    This presentation will be made at the 92nd AIAA Turbine Engine Testing Working Group (TETWoG), a semi-annual technical meeting of turbine engine testing professionals. The objective is to describe an effort by NASA to measure the water vapor content on the core airflow in a full scale turbine engine ice crystal icing test and to open a discussion with colleagues how to accurately conduct the measurement based on any previous collective experience with the procedure, instruments and nature of engine icing testing within the group. The presentation lays out the schematics of the location in the flow path from which the sample will be drawn, the plumbing to get it from the engine flow path to the sensor and several different water vapor measurement technologies that will be used: Tunable diode laser and infrared spectroscopy.

  17. Production circulator fabrication and testing for core flow test loop. Final report, Phase III

    International Nuclear Information System (INIS)

    1981-05-01

    The performance testing of two production helium circulators utilizing gas film lubrication is described. These two centrifugal-type circulators plus an identical circulator prototype will be arranged in series to provide the helium flow requirements for the Core Flow Test Loop which is part of the Gas-Cooled Fast Breeder Reactor Program (GCFR) at the Oak Ridge National Laboratory. This report presents the results of the Phase III performance and supplemental tests, which were carried out by MTI during the period of December 18, 1980 through March 19, 1981. Specific test procedures are outlined and described, as are individual tests for measuring the performance of the circulators. Test data and run descriptions are presented

  18. A flow test for calibrating 177 core tubes of 1/5-scale reactor flow model for Yonggwang nuclear units 3 and 4

    International Nuclear Information System (INIS)

    Lee, Byung Jin; Jang, Ho Cheol; Cheong, Jong Sik; Kuh, Jung Eui

    1990-01-01

    A flow test was performed to find out the hydraulic characteristics of every one of 177 core tubes, representing a fuel assembly respectively, as a preparatory step of 1/5 scale reactor flow model test for Yonggwang Nuclear Units (hereafter YGN) 3 and 4. The axial hydraulic resistance of the fuel assembly was simulated in the square core tube with six orifice plates positioned along the tube length; core support structure below each fuel assembly was done in the core upstream geometry section of the test loop. For each core tube the pressure differentials across the inlet, exit orifice plate and overall tube length were measured, along with the flow rates and temperatures of the test fluid. The measured pressure drops were converted to pressure loss or flow metering coefficients. The metering coefficient of the inlet orifice plate was sensitive to the configuration and location of the upstream geometry. The hydraulic resistance of the core tubes were reasonably coincided with a target value and consistent. The polynomial curve fits of the calibrated coefficients for the 177 core tubes were obtained with reasonable data scatters

  19. Compositional variation within thick (>10 m) flow units of Mauna Kea Volcano cored by the Hawaii Scientific Drilling Project

    Science.gov (United States)

    Huang, Shichun; Vollinger, Michael J.; Frey, Frederick A.; Rhodes, J. Michael; Zhang, Qun

    2016-07-01

    Geochemical analyses of stratigraphic sequences of lava flows are necessary to understand how a volcano works. Typically one sample from each lava flow is collected and studied with the assumption that this sample is representative of the flow composition. This assumption may not be valid. The thickness of flows ranges from 100 m. Geochemical heterogeneity in thin flows may be created by interaction with the surficial environment whereas magmatic processes occurring during emplacement may create geochemical heterogeneities in thick flows. The Hawaii Scientific Drilling Project (HSDP) cored ∼3.3 km of basalt erupted at Mauna Kea Volcano. In order to determine geochemical heterogeneities in a flow, multiple samples from four thick (9.3-98.4 m) HSDP flow units were analyzed for major and trace elements. We found that major element abundances in three submarine flow units are controlled by the varying proportion of olivine, the primary phenocryst phase in these samples. Post-magmatic alteration of a subaerial flow led to loss of SiO2, CaO, Na2O, K2O and P2O5, and as a consequence, contents of immobile elements, such as Fe2O3 and Al2O3, increase. The mobility of SiO2 is important because Mauma Kea shield lavas divide into two groups that differ in SiO2 content. Post-magmatic mobility of SiO2 adds complexity to determining if these groups reflect differences in source or process. The most mobile elements during post-magmatic subaerial and submarine alteration are K and Rb, and Ba, Sr and U were also mobile, but their abundances are not highly correlated with K and Rb. The Ba/Th ratio has been used to document an important role for a plagioclase-rich source component for basalt from the Galapagos, Iceland and Hawaii. Although Ba/Th is anomalously high in Hawaiian basalt, variation in Ba abundance within a single flow shows that it is not a reliable indicator of a deep source component. In contrast, ratios involving elements that are typically immobile, such as La/Nb, La

  20. A waveless free surface flow past a submerged triangular obstacle in presence of surface tension

    Directory of Open Access Journals (Sweden)

    Hakima Sekhri

    2016-07-01

    Full Text Available We consider the Free surface flows passing a submerged triangular obstacle at the bottom of a channel. The problem is characterized by a nonlinear boundary condition on the surface of unknown configuration. The analytical exact solutions for these problems are not known. Following Dias and Vanden Broeck [6], we computed numerically the solutions via a series truncation method. These solutions depend on two parameters: the Weber number $\\alpha$ characterizing the strength of the surface tension and the angle $\\beta$ at the base characterizing the shape of the apex. Although free surface flows with surface tension admit capillary waves, it is found that solution exist only for values of the Weber number greater than $\\alpha_0$ for different configurations of the triangular obstacle.

  1. Turbulent flow over an interactive alternating land-water surface

    Science.gov (United States)

    Van Heerwaarden, C.; Mellado, J. P.

    2014-12-01

    The alternating land-water surface is a challenging surface to represent accurately in weather and climate models, but it is of great importance for the surface energy balance in polar regions. The complexity of this surface lies in the fact that secondary circulations, which form at the boundary of water and land, interact strongly with the surface energy balance. Due to its large heat capacity, the water temperature adapts slowly to the flow, thus the properties of the atmosphere determine the uptake of energy from the water. In order to study this complex system in a simpler way, retaining only the most essential physics, we have simplified the full surface energy balance including radiation. We have derived a boundary condition that mimics the full balance and can be formulated as a so-called Robin boundary condition: a linear combination of Dirichlet (fixed temperature) and Neumann (fixed temperature gradient) ones. By spatially varying the coefficients, we are able to express land and water using this boundary condition. We have done a series of direct numerical simulations in which we generate artificial land-water patterns from noise created from a Gaussian spectrum centered around a dominant wave number. This method creates realistic random patterns, but we are still in control of the length scales. We show that the system can manifest itself in three regimes: micro-, meso- and macro-scale. In the micro-scale, we find perfect mixing of the near-surface atmosphere that results in identical air properties over water and land. In the meso-scale, secondary circulations alter the heat exchange considerably by advecting air between land and water. In addition, they bring the surface temperature of the land closer to that of the air, thereby modulating the energy loss due to outgoing longwave radiation. In the macro-scale regime, the flow over land and water become independent of each other and only the large scale forcings determine the energy balance.

  2. 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.

  3. Heat Transfer Enhancement in Turbulent Flows by Blocked Surfaces

    Directory of Open Access Journals (Sweden)

    Onur YEMENİCİ

    2013-04-01

    Full Text Available In this study, the heat transfer analyses over flat and blocked surfaces were carried out in turbulent flow under the influence of the block height. A constant-temperature hot wire anemometer was used to the velocity and turbulent intensity measurements, while temperature values were measured by copper-constantan thermocouples. The average Stanton numbers for block heights of 15 and 25 mm were higher than those of flat surface by %38 and %84, respectively. The results showed that the presence of the blocks increased the heat transfer and the enhancement rose with block heights

  4. Flow and heat transfer regimes during quenching of hot surfaces

    International Nuclear Information System (INIS)

    Barnea, Y.; Elias, E.

    1993-05-01

    Reflooding experiments have been performed to study flow and heat transfer regimes in a heated annular vertical channel under supercooled inlet conditions. A gamma densitometer was employed to determine the void fraction as a function of the distance from the quench front. Surface heat fluxes were determined by fast measurements of the temperature spatial distribution. Two quench front is shown to lie in the transition boiling region which spreads into the dry and wet segments of the heated surface. (authors) 5 refs, 3 figs

  5. Measuring surface flow velocity with smartphones: potential for citizen observatories

    Science.gov (United States)

    Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

    2014-05-01

    Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

  6. Surface Plasmon Scattering in Exposed Core Optical Fiber for Enhanced Resolution Refractive Index Sensing.

    Science.gov (United States)

    Klantsataya, Elizaveta; François, Alexandre; Ebendorff-Heidepriem, Heike; Hoffmann, Peter; Monro, Tanya M

    2015-09-29

    Refractometric sensors based on optical excitation of surface plasmons on the side of an optical fiber is an established sensing architecture that has enabled laboratory demonstrations of cost effective portable devices for biological and chemical applications. Here we report a Surface Plasmon Resonance (SPR) configuration realized in an Exposed Core Microstructured Optical Fiber (ECF) capable of optimizing both sensitivity and resolution. To the best of our knowledge, this is the first demonstration of fabrication of a rough metal coating suitable for spectral interrogation of scattered plasmonic wave using chemical electroless plating technique on a 10 μm diameter exposed core of the ECF. Performance of the sensor in terms of its refractive index sensitivity and full width at half maximum (FWHM) of SPR response is compared to that achieved with an unstructured bare core fiber with 140 μm core diameter. The experimental improvement in FWHM, and therefore the detection limit, is found to be a factor of two (75 nm for ECF in comparison to 150 nm for the large core fiber). Refractive index sensitivity of 1800 nm/RIU was achieved for both fibers in the sensing range of aqueous environment (1.33-1.37) suitable for biosensing applications.

  7. Operation manual for the core flow test loop zone power-supply controller

    Energy Technology Data Exchange (ETDEWEB)

    Harper, R.E.

    1981-11-01

    The core flow test loop, which is part of the Gas-Cooled Fast Breeder Reactor Program (GCFR) at ORNL, is a high-pressure, high-temperature, out-of-reactor helium circulation system that is being constructed to permit study of the performance at steady-state and transient conditions of simulated segments of core assemblies for a GCFR demonstration plant. The simulated core segments, which are divided into zones, contain electrical heating elements to simulate the heat generated by fission. To control the power which is applied to a zone, a novel multitapped transformer and zone power control system have been designed and built which satisfy stringent design criteria. The controller can match power output to demand to within better than +-1% over a 900:1 dynamic range and perform full-power transients within 1 s. The power is applied in such a way as to minimize the electromagnetic interference at the bandwidth of the loop instrumentation, and the controller incorporates several error detection techniques, making it inherently fail-safe. The operation manual describes the specifications, operating instructions, error detection capabilities, error recovery, troubleshooting, calibration and QA procedures, and maintenance requirements. Also included are sections on the theory of operation, circuitry description, and a complete set of schematics.

  8. Mass Redistribution in the Core and Time-varying Gravity at the Earth's Surface

    Science.gov (United States)

    Kuang, Wei-Jia; Chao, Benjamin F.; Fang, Ming

    2003-01-01

    The Earth's liquid outer core is in convection, as suggested by the existence of the geomagnetic field in much of the Earth's history. One consequence of the convection is the redistribution of mass resulting from relative motion among fluid parcels with slightly different densities. This time dependent mass redistribution inside the core produces a small perturbation on the gravity field of the Earth. With our numerical dynamo solutions, we find that the mass redistribution (and the resultant gravity field) symmetric about the equator is much stronger than that anti-symmetric about the equator. In particular, J(sub 2) component is the strongest. In addition, the gravity field variation increases with the Rayleigh number that measures the driving force for the geodynamo in the core. With reasonable scaling from the current dynamo solutions, we could expect that at the surface of the Earth, the J(sub 2) variation from the core is on the order of l0(exp -16)/year relative to the mean (i.e. spherically symmetric) gravity field of the Earth. The possible shielding effect due to core-mantle boundary pressure variation loading is likely much smaller and is therefore negligible. Our results suggest that time-varying gravity field perturbation due to core mass redistribution may be measured with modem space geodetic observations, which will result a new means of detecting dynamical processes in the Earth's deep interior.

  9. Evaluation of advanced two-phase flow instrumentation in SCTF Core-1

    International Nuclear Information System (INIS)

    Iwamura, Takamichi; Sobajima, Makoto; Osakabe, Masahiro; Ohnuki, Akira; Abe, Yutaka; Sudo, Yukio; Adachi, Hiromichi

    1984-03-01

    In the Slab Core Test Facility (SCTF) Core-I, advanced two-phase flow instruments have been provided by the USNRC to measure the thermohydraulic behavior in the primary system including pressure vessel during the end of blowdown, refill and reflood phases of a postulated loss-of-coolant accident in a pressurized water reactor. The advanced instruments are turbine meters, drag disks, γ-densitometers, spool pieces, liquid level detectors (LLD), fluid distribution grids (FDG), impedance probes (flag, prong and string probes), film probes, and video optical probes. This report presents evaluated results of the data from these instruments. Some instruments are quantitatively evaluated by comparing with the data from the conventional instruments or the other advanced instruments. Main conclusions are as follows: (1) The spool pieces and the γ-densitometers work well and provide satisfactory results; (2) Some of the turbine meters, the impedance probes and the film probes give partially reasonable results, but still more improvements are required; (3) Most of the LLDs, the FDGs, the impedance probes, and the film probes do not work well due to a hard cable corrosion, and (4) The video optical probes give clear image of the flow pattern. (author)

  10. Applying CFD in the Analysis of Heavy-Oil Transportation in Curved Pipes Using Core-Flow Technique

    Directory of Open Access Journals (Sweden)

    S Conceição

    2017-06-01

    Full Text Available Multiphase flow of oil, gas and water occurs in the petroleum industry from the reservoir to the processing units. The occurrence of heavy oils in the world is increasing significantly and points to the need for greater investment in the reservoirs exploitation and, consequently, to the development of new technologies for the production and transport of this oil. Therefore, it is interesting improve techniques to ensure an increase in energy efficiency in the transport of this oil. The core-flow technique is one of the most advantageous methods of lifting and transporting of oil. The core-flow technique does not alter the oil viscosity, but change the flow pattern and thus, reducing friction during heavy oil transportation. This flow pattern is characterized by a fine water pellicle that is formed close to the inner wall of the pipe, aging as lubricant of the oil flowing in the core of the pipe. In this sense, the objective of this paper is to study the isothermal flow of heavy oil in curved pipelines, employing the core-flow technique. A three-dimensional, transient and isothermal mathematical model that considers the mixture and k-e  turbulence models to address the gas-water-heavy oil three-phase flow in the pipe was applied for analysis. Simulations with different flow patterns of the involved phases (oil-gas-water have been done, in order to optimize the transport of heavy oils. Results of pressure and volumetric fraction distribution of the involved phases are presented and analyzed. It was verified that the oil core lubricated by a fine water layer flowing in the pipe considerably decreases pressure drop.

  11. Evidence of stochastic region near a rational surface in core plasmas of LHD

    International Nuclear Information System (INIS)

    Ida, K.; Tamura, N.; Tuchiya, H.

    2010-11-01

    Clear evidence of stochastization of the magnetic surfaces near a rational surface is observed in the core plasma with weak magnetic shear in the Large Helical Device (LHD) by applying heat pulses driven by modulated electron cyclotron heating (MECH). The stochastization of the magnetic surfaces is confirmed by the observation of flattening of electron temperature (T e ) profiles and very fast propagation of the heat pulse, which is in contrast to the slow heat pulse propagation observed in the T e flat region of the nested magnetic island. (author)

  12. 3D surface reconstruction using optical flow for medical imaging

    International Nuclear Information System (INIS)

    Weng, Nan; Yang, Yee-Hong; Pierson, R.

    1996-01-01

    The recovery of a 3D model from a sequence of 2D images is very useful in medical image analysis. Image sequences obtained from the relative motion between the object and the camera or the scanner contain more 3D information than a single image. Methods to visualize the computed tomograms can be divided into two approaches: the surface rendering approach and the volume rendering approach. A new surface rendering method using optical flow is proposed. Optical flow is the apparent motion in the image plane produced by the projection of the real 3D motion onto 2D image. In this paper, the object remains stationary while the scanner undergoes translational motion. The 3D motion of an object can be recovered from the optical flow field using additional constraints. By extracting the surface information from 3D motion, it is possible to get an accurate 3D model of the object. Both synthetic and real image sequences have been used to illustrate the feasibility of the proposed method. The experimental results suggest that the proposed method is suitable for the reconstruction of 3D models from ultrasound medical images as well as other computed tomograms

  13. Building waste management core indicators through Spatial Material Flow Analysis: Net recovery and transport intensity indexes

    Energy Technology Data Exchange (ETDEWEB)

    Font Vivanco, David, E-mail: font@cml.leidenuniv.nl [Institut de Ciencia i Tecnologia Ambientals (ICTA), Departament d' Enginyeria Quimica, Universitat Autonoma de Barcelona (UAB), 08193 Bellaterra, Barcelona (Spain); Institute of Environmental Sciences (CML), Leiden University, P.O. Box 9518, 2300 RA Leiden (Netherlands); Puig Ventosa, Ignasi [ENT Environment and Management, Carrer Sant Joan 39, First Floor, 08800 Vilanova i la Geltru, Barcelona (Spain); Gabarrell Durany, Xavier [Institut de Ciencia i Tecnologia Ambientals (ICTA), Departament d' Enginyeria Quimica, Universitat Autonoma de Barcelona (UAB), 08193 Bellaterra, Barcelona (Spain)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Sustainability and proximity principles have a key role in waste management. Black-Right-Pointing-Pointer Core indicators are needed in order to quantify and evaluate them. Black-Right-Pointing-Pointer A systematic, step-by-step approach is developed in this study for their development. Black-Right-Pointing-Pointer Transport may play a significant role in terms of environmental and economic costs. Black-Right-Pointing-Pointer Policy action is required in order to advance in the consecution of these principles. - Abstract: In this paper, the material and spatial characterization of the flows within a municipal solid waste (MSW) management system are combined through a Network-Based Spatial Material Flow Analysis. Using this information, two core indicators are developed for the bio-waste fraction, the Net Recovery Index (NRI) and the Transport Intensity Index (TII), which are aimed at assessing progress towards policy-related sustainable MSW management strategies and objectives. The NRI approaches the capacity of a MSW management system for converting waste into resources through a systematic metabolic approach, whereas the TII addresses efficiency in terms of the transport requirements to manage a specific waste flow throughout the entire MSW management life cycle. Therefore, both indicators could be useful in assessing key MSW management policy strategies, such as the consecution of higher recycling levels (sustainability principle) or the minimization of transport by locating treatment facilities closer to generation sources (proximity principle). To apply this methodological approach, the bio-waste management system of the region of Catalonia (Spain) has been chosen as a case study. Results show the adequacy of both indicators for identifying those points within the system with higher capacity to compromise its environmental, economic and social performance and therefore establishing clear targets for policy

  14. Building waste management core indicators through Spatial Material Flow Analysis: Net recovery and transport intensity indexes

    International Nuclear Information System (INIS)

    Font Vivanco, David; Puig Ventosa, Ignasi; Gabarrell Durany, Xavier

    2012-01-01

    Highlights: ► Sustainability and proximity principles have a key role in waste management. ► Core indicators are needed in order to quantify and evaluate them. ► A systematic, step-by-step approach is developed in this study for their development. ► Transport may play a significant role in terms of environmental and economic costs. ► Policy action is required in order to advance in the consecution of these principles. - Abstract: In this paper, the material and spatial characterization of the flows within a municipal solid waste (MSW) management system are combined through a Network-Based Spatial Material Flow Analysis. Using this information, two core indicators are developed for the bio-waste fraction, the Net Recovery Index (NRI) and the Transport Intensity Index (TII), which are aimed at assessing progress towards policy-related sustainable MSW management strategies and objectives. The NRI approaches the capacity of a MSW management system for converting waste into resources through a systematic metabolic approach, whereas the TII addresses efficiency in terms of the transport requirements to manage a specific waste flow throughout the entire MSW management life cycle. Therefore, both indicators could be useful in assessing key MSW management policy strategies, such as the consecution of higher recycling levels (sustainability principle) or the minimization of transport by locating treatment facilities closer to generation sources (proximity principle). To apply this methodological approach, the bio-waste management system of the region of Catalonia (Spain) has been chosen as a case study. Results show the adequacy of both indicators for identifying those points within the system with higher capacity to compromise its environmental, economic and social performance and therefore establishing clear targets for policy prioritization. Moreover, this methodological approach permits scenario building, which could be useful in assessing the outcomes of

  15. Self-consistent Green’s-function technique for bulk and surface impurity calculations: Surface core-level shifts by complete screening

    DEFF Research Database (Denmark)

    Aldén, M.; Abrikosov, I. A.; Johansson, B.

    1994-01-01

    of the frozen-core and atomic-sphere approximation but, in addition, includes the dipole contribution to the intersphere potential. Within the concept of complete screening, we identify the surface core-level binding-energy shift with the surface segregation energy of a core-ionized atom and use the Green......'s-function impurity technique in a comprehensive study of the surface core-level shifts (SCLS) of the 4d and 5d transition metals. In those cases, where observed data refer to single crystals, we obtain good agreement with experiment, whereas the calculations typically underestimate the measured shift obtained from...

  16. Evaluation of effective coolant flow rate in advanced design of the small scale VHTR core

    International Nuclear Information System (INIS)

    Fumizawa, Motoo; Suzuki, Kunihiko; Murakami, Tomoyuki.

    1988-02-01

    This report describes the evaluation of effective coolant flow rate in the advanced design of the small scale VHTR core. The analytical design study was carried out after the 2nd stage of detailed design in order to reduce the cost of construction. The summary of the analytical results are as follows: (1) Crossflow loss coefficient of flange type fuel block having 0.1 mm of sealing gap is about 100 times higher than that of dowel type block adopted in the 2nd stage of detailed design. (2) In case that coolant channel outer diameter is 52 mm and hydraulic diameter is 6 mm, the effective coolant flow rates using flange and dowel type fuel blocks are 80 % and 70 % respectively. Because the crossflow loss coefficients of dowel type are lower than that of flange type. (3) The effective coolant flow rate, when crossflow loss coefficients are distributed along with the axial direction, agrees well with that using mean value of crossflow loss coefficient i.e. 5 x 10 11 m -4 . (author)

  17. Building waste management core indicators through Spatial Material Flow Analysis: net recovery and transport intensity indexes.

    Science.gov (United States)

    Font Vivanco, David; Puig Ventosa, Ignasi; Gabarrell Durany, Xavier

    2012-12-01

    In this paper, the material and spatial characterization of the flows within a municipal solid waste (MSW) management system are combined through a Network-Based Spatial Material Flow Analysis. Using this information, two core indicators are developed for the bio-waste fraction, the Net Recovery Index (NRI) and the Transport Intensity Index (TII), which are aimed at assessing progress towards policy-related sustainable MSW management strategies and objectives. The NRI approaches the capacity of a MSW management system for converting waste into resources through a systematic metabolic approach, whereas the TII addresses efficiency in terms of the transport requirements to manage a specific waste flow throughout the entire MSW management life cycle. Therefore, both indicators could be useful in assessing key MSW management policy strategies, such as the consecution of higher recycling levels (sustainability principle) or the minimization of transport by locating treatment facilities closer to generation sources (proximity principle). To apply this methodological approach, the bio-waste management system of the region of Catalonia (Spain) has been chosen as a case study. Results show the adequacy of both indicators for identifying those points within the system with higher capacity to compromise its environmental, economic and social performance and therefore establishing clear targets for policy prioritization. Moreover, this methodological approach permits scenario building, which could be useful in assessing the outcomes of hypothetical scenarios, thus proving its adequacy for strategic planning. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. On the flow magnitude and field-flow alignment at Earth's core surface

    DEFF Research Database (Denmark)

    Finlay, Chris; Amit, H.

    ,with results differing from reference values by less than 8%.Application to a high quality geomagnetic field model based on satelliteobservations (the xCHAOS model in epoch 2004.0) leads to a flowmagnitude estimate of 11 - 14 km / yr, in accordance with previousestimates. When applied to the historical...

  19. Application of the extended Kalman filtering for the estimation of core coolant flow rate in pressurized water reactors

    International Nuclear Information System (INIS)

    Shieh, D.J.; Upadhyaya, B.R.

    1986-01-01

    In-core neutron detector and core-exit temperature signals in a pressurized water reactor (PWR) satisfy the condition of observability of the core dynamic system, and can be used to estimate nonmeasurable state variables and model parameters. The extension of the Kalman filtering technique is very useful for direct parameter estimation. This approach is applied to the determination of core coolant mass flow rate in PWRs and is evaluated using in-core measurements at the Loss-of-Fluid Test (LOFT) reactor. The influence of model uncertainties on the estimation accuracy was studied using the ambiguity function analysis. A sequential discretization method was developed to achieve faster convergence to the true value, avoiding model discretization at each sample point. The performance of the extended Kalman filter and the computational innovations were evaluated using a reduced order core dynamic model of the LOFT reactor and random data simulation. The technique was then applied to the determination of LOFT core coolant flow rate from operational data at 100% and 65% flow conditions

  20. Strippable core-shell polymer emulsion for decontamination of radioactive surface contamination

    International Nuclear Information System (INIS)

    Hwang, Ho-Sang; Seo, Bum-Kyoung; Lee, Kune-Woo

    2011-01-01

    In this study, the core-shell composite polymer for decontamination from the surface contamination was synthesized by the method of emulsion polymerization and blends of polymers. The strippable polymer emulsion is composed of the poly(styrene-ethyl acrylate) [poly(St-EA)] composite polymer, poly(vinyl alcohol) (PVA) and polyvinylpyrrolidone (PVP). The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS) as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SDS) as an emulsifier using ammonium persulfate (APS) as an initiator. Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by FT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Decontamination factors of the strippable polymeric emulsion were evaluated with the polymer blend contents. (author)

  1. Replication of Annual Cycles in Mn in Hudson River Cores: Mn Peaks During High Water Flow

    Science.gov (United States)

    Abbott, D. H.; Hutson, D.; Marrero, A. M.; Block, K. A.; Chang, C.; Cai, Y.

    2017-12-01

    Using the results from an ITRAX, XRF scanner, we previously reported apparent annual cycles in Mn in a single, high sedimentation rate Hudson River core, LWB1-8, taken off Yonkers, NY (Carlson et al., 2016). We replicated these results in three more high sedimentation rate cores and found stratigraphic markers that verify our inferences about the annual nature of the Mn cycles. The three new cores are LWB4-5 taken off Peekskill, NY, and LWB3-44 and LWB3-25, both taken in Haverstraw Bay. The cores are from water depths of 7-9 meters and all have high magnetic susceptibilities (typically > 30 cgs units) in their upper 1 to 2 meters. The high susceptibilities are primarily produced by magnetite from modern industrial combustion. One core, LWB1-8, has reconnaissance Cs dates that verify the annual nature of the cycles. More Cs dates are expected before the meeting. We developed several new methods of verifying the annual nature of our layer counts. The first is looking at the grain size distribution and age of layers with unusually high Mn peaks. Peaks in Si, Ni and Ti and peaks in percentage of coarse material typically accompany the peaks in Mn. Some are visible as yellow sandy layers. The five highest peaks in Mn in LWB1-8 have layer counted ages that correspond (within 1 year in the top meter and within 2 years in the bottom meter) to 1996, 1948, 1913, 1857 and 1790. The latter three events are the three largest historical spring freshets on the Hudson. 1996 is a year of unusually high flow rate during the spring freshet. Based on our work and previous work on Mn cycling in rivers, we infer that the peaks in Mn are produced by extreme erosional events that erode sediment and release pore water Mn into the water column. The other methods of testing our chronology involve marine storms that increase Ca and Sr and a search for fragments of the Peekskill meteorite that fell in October 1992. More information on the latter will be available by the meeting.

  2. Entropy flow and generation in radiative transfer between surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.M.; Basu, S. [Georgia Institute of Technolgy, Atlanta, GA (United States). George W. Woodruff School of Mechanical Engineering

    2007-02-15

    Entropy of radiation has been used to derive the laws of blackbody radiation and determine the maximum efficiency of solar energy conversion. Along with the advancement in thermophotovoltaic technologies and nanoscale heat radiation, there is an urgent need to determine the entropy flow and generation in radiative transfer between nonideal surfaces when multiple reflections are significant. This paper investigates entropy flow and generation when incoherent multiple reflections are included, without considering the effects of interference and photon tunneling. The concept of partial equilibrium is applied to interpret the monochromatic radiation temperature of thermal radiation, T{sub l}(l,{omega}), which is dependent on both wavelength l and direction {omega}. The entropy flux and generation can thus be evaluated for nonideal surfaces. It is shown that several approximate expressions found in the literature can result in significant errors in entropy analysis even for diffuse-gray surfaces. The present study advances the thermodynamics of nonequilibrium thermal radiation and will have a significant impact on the future development of thermophotovoltaic and other radiative energy conversion devices. (author)

  3. Gases Emission From Surface Layers of Sand Moulds and Cores Stored Under the Humid Air Conditions

    Directory of Open Access Journals (Sweden)

    Kaźnica N.

    2017-12-01

    Full Text Available A large number of defects of castings made in sand moulds is caused by gases. There are several sources of gases: gases emitted from moulds, cores or protective coatings during pouring and casting solidification; water in moulding sands; moisture adsorbed from surroundings due to atmospheric conditions changes. In investigations of gas volumetric emissions of moulding sands amounts of gases emitted from moulding sand were determined - up to now - in dependence of the applied binders, sand grains, protective coatings or alloys used for moulds pouring. The results of investigating gas volumetric emissions of thin-walled sand cores poured with liquid metal are presented in the hereby paper. They correspond to the surface layer in the mould work part, which is decisive for the surface quality of the obtained castings. In addition, cores were stored under conditions of a high air humidity, where due to large differences in humidity, the moisture - from surroundings - was adsorbed into the surface layer of the sand mould. Due to that, it was possible to asses the influence of the adsorbed moisture on the gas volumetric emission from moulds and cores surface layers by means of the new method of investigating the gas emission kinetics from thin moulding sand layers heated by liquid metal. The results of investigations of kinetics of the gas emission from moulding sands with furan and alkyd resins as well as with hydrated sodium silicate (water glass are presented. Kinetics of gases emissions from these kinds of moulding sands poured with Al-Si alloy were compared.

  4. Examination of the effect of blowing on the near-surface flow structure over a dimpled surface

    Science.gov (United States)

    Borchetta, C. G.; Martin, A.; Bailey, S. C. C.

    2018-03-01

    The near surface flow over a dimpled surface with flow injection through it was documented using time-resolved particle image velocimetry. The instantaneous flow structure, time-averaged statistics, and results from snapshot proper orthogonal decomposition were used to examine the coherent structures forming near the dimpled surface. In particular, the modifications made to the flow structures by the addition of flow injection through the surface were studied. It was observed that without flow injection, inclined flow structures with alternating vorticity from neighboring dimples are generated by the dimples and advect downstream. This behavior is coupled with fluid becoming entrained inside the dimples, recirculating and ejecting away from the surface. When flow injection was introduced through the surface, the flow structures became more disorganized, but some of the features of the semi-periodic structures observed without flow injection were preserved. The structures with flow injection appear in multiple wall-normal layers, formed from vortical structures shed from upstream dimples, with a corresponding increase in the size of the advecting structures. As a result of the more complex flow field observed with flow injection, there was an increase in turbulent kinetic energy and Reynolds shear stress, with the Reynolds shear stress representing an increase in vertical transport of momentum by sweeping and ejecting motions that were not present without flow injection.

  5. Behaviour of steel pipe exposed to fouling by heavy oil during core-annular flow; Comportamento de tubo de aco exposto a sujeira de oleo pesado durante escoamento nucleo-anular

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Adriana; Bannwart, Antonio C. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Petroleo

    2004-07-01

    The use of water-assisted technologies such as core-annular flow to the pipelines of viscous oils has been proposed as an attractive alternative for production and transportation of heavy crudes in both onshore and offshore scenarios. Usually, core-annular flow can be created by injecting a relatively small water flow rate laterally in the pipe, so as to form a thin water annulus surrounding the viscous oil, which is pumped through the center. The reduction in friction losses obtained thanks to lubrication by water is significant, since the pressure drop in a steady state core flow becomes comparable to water flow only. For a complete assessment of core flow technology, however, unwanted effects associated with possible oil adhesion onto the pipe wall should be investigated, since these may cause severe fouling of the wall and pressure drop increase. It has been observed that oil adhesion on metallic surfaces may occur for certain types of crude and oilphilic pipe materials. In this work we present results of pressure drop monitoring during 35 hour-operation of a heavy oil-water core annular flow in a 26.08 mm. i.d. horizontal steel pipe. The oil used is described in terms of its main components and the results of static wet ability tests are also presented for comparison (author)

  6. One Core Phase Shifting Transformer for Control of the Power Flow Distribution in Electric Networks

    Directory of Open Access Journals (Sweden)

    Golub I.V.

    2016-08-01

    Full Text Available This paper presents the variant of phase shifting transformer that is made, unlike from traditional technology, on the basis of only one magnetic core. The paper describes the methodology related to the analysis of operation modes of device and its components. Additionally it presents a mathematical model of device with determines the relationship between input and output electric quantities as well as own longitudinal and transverse parameters of an equivalent circuit of phase shifting transformer (PST. Proposed configuration of PST is interesting from an economic and operational consideration; enable continuous control of power flow distribution in electric networks as a result of regulation a phase shift angle between input and output voltages of device.

  7. Application of Intel Many Integrated Core (MIC) accelerators to the Pleim-Xiu land surface scheme

    Science.gov (United States)

    Huang, Melin; Huang, Bormin; Huang, Allen H.

    2015-10-01

    The land-surface model (LSM) is one physics process in the weather research and forecast (WRF) model. The LSM includes atmospheric information from the surface layer scheme, radiative forcing from the radiation scheme, and precipitation forcing from the microphysics and convective schemes, together with internal information on the land's state variables and land-surface properties. The LSM is to provide heat and moisture fluxes over land points and sea-ice points. The Pleim-Xiu (PX) scheme is one LSM. The PX LSM features three pathways for moisture fluxes: evapotranspiration, soil evaporation, and evaporation from wet canopies. To accelerate the computation process of this scheme, we employ Intel Xeon Phi Many Integrated Core (MIC) Architecture as it is a multiprocessor computer structure with merits of efficient parallelization and vectorization essentials. Our results show that the MIC-based optimization of this scheme running on Xeon Phi coprocessor 7120P improves the performance by 2.3x and 11.7x as compared to the original code respectively running on one CPU socket (eight cores) and on one CPU core with Intel Xeon E5-2670.

  8. Denali Ice Core Record of North Pacific Sea Surface Temperatures and Marine Primary Productivity

    Science.gov (United States)

    Polashenski, D.; Osterberg, E. C.; Kreutz, K. J.; Winski, D.; Wake, C. P.; Ferris, D. G.; Introne, D.; Campbell, S. W.

    2016-12-01

    Chemical analyses of precipitation preserved in glacial ice cores provide a unique opportunity to study changes in atmospheric circulation patterns and ocean surface conditions through time. In this study, we aim to investigate changes in both the physical and biological parameters of the north-central Pacific Ocean and Bering Sea over the twentieth century using the deuterium excess (d-excess) and methanesulfonic acid (MSA) records from the Mt. Hunter ice cores drilled in Denali National Park, Alaska. These parallel, 208 m-long ice cores were drilled to bedrock during the 2013 field season on the Mt. Hunter plateau (63° N, 151° W, 3,900 m above sea level) by a collaborative research team consisting of members from Dartmouth College and the Universities of Maine and New Hampshire. The cores were sampled on a continuous melter system at Dartmouth College and analyzed for the concentrations major ions (Dionex IC) and trace metals (Element2 ICPMS), and for stable water isotope ratios (Picarro). The depth-age scale has been accurately dated to 400 AD using annual layer counting of several chemical species and further validated using known historical volcanic eruptions and the Cesium-137 spike associated with nuclear weapons testing in 1963. We use HYSPLIT back trajectory modeling to identify likely source areas of moisture and aerosol MSA being transported to the core site. Satellite imagery allows for a direct comparison between chlorophyll a concentrations in these source areas and MSA concentrations in the core record. Preliminary analysis of chlorophyll a and MSA concentrations, both derived almost exclusively from marine biota, suggest that the Mt. Hunter ice cores reflect changes in North Pacific and Bering Sea marine primary productivity. Analysis of the water isotope and MSA data in conjunction with climate reanalysis products shows significant correlations (psea surface temperatures in the Bering Sea and North Central Pacific. These findings, coupled with

  9. Development of Sodium Two Phase Flow Model for Kalimer Core Analysis

    International Nuclear Information System (INIS)

    Chang, W.P.; Hahn, Dohee

    2002-01-01

    An algorithm for sodium boiling is developed in order to extend the applicability of SSC-K, which is a main system analysis code for the KALIMER (Korea Advanced LIquid Metal Reactor) conceptual design. As the capability of the current SSC-K version is limited to simulation of only a single-phase sodium flow, its applicable range should not be enough to assess the fuel integrity under some of HCDA (Hypothetical Core Disruptive Accident) initiating events where sodium boiling is anticipated. The two-phase flow model similar to that used for the light water system is known to be no more effective directly to liquid metal reactors, because the phenomena observed between two reactor coolant systems are definitely different. The developing algorithm is based on a multiple-bubble slug ejection model, which allows a finite number of bubbles in a channel at any time. The present work is a continuous effort following the former study to confirm a qualitative acceptance on the model. Since the model has been applied only to the active fuel region in the former study, a part of its qualification seems to have already been demonstrated. For its application to the whole KALIMER core channel, however, the model needs to be examined the applicability to the fuel regions other than the active fuel. The present study primarily focuses on that point. In a result, although the model may be improved in a sense through the present study over the previous modeling, a clear limitation is also confirmed with the validity of the model. The further development, therefore, is required for this model to achieve its goal by resolving such limitations. (authors)

  10. Effect of non-equilibrium flow chemistry and surface catalysis on surface heating to AFE

    Science.gov (United States)

    Stewart, David A.; Henline, William D.; Chen, Yih-Kanq

    1991-01-01

    The effect of nonequilibrium flow chemistry on the surface temperature distribution over the forebody heat shield on the Aeroassisted Flight Experiment (AFE) vehicle was investigated using a reacting boundary-layer code. Computations were performed by using boundary-layer-edge properties determined from global iterations between the boundary-layer code and flow field solutions from a viscous shock layer (VSL) and a full Navier-Stokes solution. Surface temperature distribution over the AFE heat shield was calculated for two flight conditions during a nominal AFE trajectory. This study indicates that the surface temperature distribution is sensitive to the nonequilibrium chemistry in the shock layer. Heating distributions over the AFE forebody calculated using nonequilibrium edge properties were similar to values calculated using the VSL program.

  11. Experimental investigation of flow dynamics in the SNR-upper-core structure

    International Nuclear Information System (INIS)

    Meyer, L.

    1985-03-01

    This report describes the results of a simulant-material experimental investigation of flow dynamics in the upper-core (UCS) during a HCDA of a LMFBR. The experiments were designed to verify some of the thermal-hydraulic models in SIMMER-II. Four different liquids were used to simulate the flashing U0 2 ; and numerous parameter variations were made regarding initial pressure, temperature, and configurations of the test apparatus. The experiments showed the large effect of the heat transfer in the UCS and the relatively small effect of friction. The reduction in final kinetic energy by the presence of the UCS is shown as a function of the initial pressure and the temperature difference between core and UCS. Calculations with SIMMER-II for the wide range of experiments produced results for the kinetic energy within a factor of 2 of the experimental results without changing the crucial input parameters. The minimum droplet size during the flashing process and the structure-side heat transfer coefficient were determined to be the crucial and most sensitive parameters. This reflects deficiencies in modeling of both the flashing process and the transient heat conduction in the structure. (orig./HP) [de

  12. In-core fuel element temperature and flow measurment of HFETR

    International Nuclear Information System (INIS)

    Chen Daolong; Jiang Pei

    1988-02-01

    The HFETR in-core fuel element temperature-flow measurement facility and its measurement system are expounded. The applications of the instrumented fuel element to stationary and transient states measurements during the lift of power, the operation test of all lifetime at first load, and the deepening burn-up test at second load are described. The method of determination of the hot point temperature under the fin is discussed. The error analysis is made. The fuel element out-of-pile water deprivation test is described. The development of this measurement facility and succesful application have made important contribution to high power and deep burn-up safe operation at two load, in-core fuel element irradiation, and varied investigation of HFETR. After operation at two loads, the integrated power of this instrumented fuel element arrives at 90.88 MWd, its maximum point burn-up is about 64.9%, so that the economy of fuel use of HFETR is raised very much

  13. Alkyl-terminated Si(111) surfaces: A high-resolution, core level photoelectron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Terry, J.; Linford, M.R.; Wigren, C.; Cao, R.; Pianetta, P.; Chidsey, C.E. [Stanford University, Stanford, California 94309 (United States)

    1999-01-01

    The bonding of alkyl monolayers to Si(111) surfaces has been studied with high-resolution core level photoelectron spectroscopy (PES). Two very different wet-chemical methods have been used to prepare the alkyl monolayers: (i) Olefin insertion into the H{endash}Si bond of the H{endash}Si(111) surface, and (ii) replacement of Cl on the Cl{endash}Si(111) surface by an alkyl group from an alkyllithium reagent. In both cases, PES has revealed a C 1s component shifted to lower binding energy and a Si 2p component shifted to higher binding energy. Both components are attributed to the presence of a C{endash}Si bond at the interface. Along with photoelectron diffraction data [Appl. Phys. Lett. {bold 71}, 1056, (1997)], these data are used to show that these two synthetic methods can be used to functionalize the Si(111) surface. {copyright} {ital 1999 American Institute of Physics.}

  14. Flux surface shaping effects on tokamak edge turbulence and flows

    International Nuclear Information System (INIS)

    Kendl, A.; Scott, B.D.

    2004-01-01

    The influence of shaping of magnetic flux surfaces in tokamaks on gyro-fluid edge turbulence is studied numerically. Magnetic field shaping in tokamaks is mainly due to elongation, triangularity, shift and the presence of a divertor X-point. A series of tokamak configurations with varying elongation 1 ≤ κ ≥ 2 and triangularity 0 ≤ δ ≤ 0.4, and an actual ASDEX Upgrade divertor configuration are obtained with the equilibrium code HELENA and implemented into the gyro-fluid turbulence code GEM. The study finds minimal impact on the zonal flow physics itself, but strong impact on the turbulence and transport. (authors)

  15. Flux surface shaping effects on tokamak edge turbulence and flows

    Energy Technology Data Exchange (ETDEWEB)

    Kendl, A. [Innsbruck Univ., Institut fuer Theoretische Physik, Association EURATOM (Austria); Scott, B.D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei Muenchen (Germany)

    2004-07-01

    The influence of shaping of magnetic flux surfaces in tokamaks on gyro-fluid edge turbulence is studied numerically. Magnetic field shaping in tokamaks is mainly due to elongation, triangularity, shift and the presence of a divertor X-point. A series of tokamak configurations with varying elongation 1 {<=} {kappa} {>=} 2 and triangularity 0 {<=} {delta} {<=} 0.4, and an actual ASDEX Upgrade divertor configuration are obtained with the equilibrium code HELENA and implemented into the gyro-fluid turbulence code GEM. The study finds minimal impact on the zonal flow physics itself, but strong impact on the turbulence and transport. (authors)

  16. DIVERGENT HORIZONTAL SUB-SURFACE FLOWS WITHIN ACTIVE REGION 11158

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Kiran; Tripathy, S. C.; Hill, F., E-mail: kjain@nso.edu, E-mail: stripathy@nso.edu, E-mail: fhill@nso.edu [National Solar Observatory, 950 N Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-07-20

    We measure the horizontal subsurface flow in a fast emerging active region (AR; NOAA 11158) using the ring-diagram technique and the Helioseismic and Magnetic Imager high spatial resolution Dopplergrams. This AR had a complex magnetic structure and displayed significant changes in morphology during its disk passage. Over a period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of the total velocity is found to follow the trend of magnetic field strength. We further analyze regions of individual magnetic polarity within AR 11158 and find that the horizontal velocity components in these sub-regions have significant variation with time and depth. The leading and trailing polarity regions move faster than the mixed-polarity region. Furthermore, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the AR. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layers around major flares. It is suggested that the re-organization of magnetic fields during flares, combined with the sunspot rotation, decreases the magnitude of horizontal flows or that the flow kinetic energy has been converted into the energy released by flares. After the decline in flare activity and sunspot rotation, the flows tend to follow the pattern of magnetic activity. We also observe less variation in the velocity components near the surface but these tend to increase with depth, further demonstrating that the deeper layers are more affected by the topology of ARs.

  17. Correlations of Surface Deformation and 3D Flow Field in a Compliant Wall Turbulent Channel Flow.

    Science.gov (United States)

    Wang, Jin; Zhang, Cao; Katz, Joseph

    2015-11-01

    This study focuses on the correlations between surface deformation and flow features, including velocity, vorticity and pressure, in a turbulent channel flow over a flat, compliant Polydimethylsiloxane (PDMS) wall. The channel centerline velocity is 2.5 m/s, and the friction Reynolds number is 2.3x103. Analysis is based on simultaneous measurements of the time resolved 3D velocity and surface deformation using tomographic PIV and Mach-Zehnder Interferometry. The volumetric pressure distribution is calculated plane by plane by spatially integrating the material acceleration using virtual boundary, omni-directional method. Conditional sampling based on local high/low pressure and deformation events reveals the primary flow structures causing the deformation. High pressure peaks appear at the interface between sweep and ejection, whereas the negative deformations peaks (dent) appear upstream, under the sweeps. The persistent phase lag between flow and deformations are presumably caused by internal damping within the PDMS. Some of the low pressure peaks and strong ejections are located under the head of hairpin vortices, and accordingly, are associated with positive deformation (bump). Others bumps and dents are correlated with some spanwise offset large inclined quasi-streamwise vortices that are not necessarily associated with hairpins. Sponsored by ONR.

  18. Fuel assembly outlet temperature profile influence on core by-pass flow and power distribution determination in WWER -440 reactors

    International Nuclear Information System (INIS)

    Petenyi, V.; Klucarova, K.; Remis, J.

    2003-01-01

    The in core instrumentation of the WWER-440 reactors consists of the thermocouple system and the system of self powered detectors (SPD). The thermocouple systems are positioned about 50 cm above the fuel bundle upper flow-mixing grid. The usual assumption is that, the coolant is well mixed in the Tc location, i.e. the temperature is constant through the flow cross-section area. The present evaluations by using the FLUENT 5.5.14 code reveal that, this assumption is not fulfilled. There exists a temperature profile that depends on fuel assembly geometry and on inner power profile of the fuel assembly. The paper presents the estimation of this effect and its influence on the core power distribution and the core by-pass flow determination. Comparison with measurements in Mochovce NPP will also be a part of this presentation (Authors)

  19. Topological Fluid Mechanics with Applications to Free Surfaces and Axisymmetric Flows

    DEFF Research Database (Denmark)

    Brøns, Morten

    1996-01-01

    Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow.......Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow....

  20. Turbulence modeling and surface heat transfer in a stagnation flow region

    Science.gov (United States)

    Wang, C. R.; Yeh, F. C.

    1987-01-01

    Analysis for the turbulent flow field and the effect of freestream turbulence on the surface heat transfer rate of a stagnation flow is presented. The emphasis is on modeling and its augmentation of surface heat transfer rate. The flow field considered is the region near the forward stagnation point of a circular cylinder in a uniform turbulent mean flow.

  1. Increase of body surface temperature and blood flow by theanine

    International Nuclear Information System (INIS)

    Hasegawa, Takeo; Noguchi, Kenichi; Ando, Satoshi

    2002-01-01

    Suntheanine (Taiyo Kagaku Co.: Theanine) is the trade name for L-theanine which is a unique amino acid found almost solely in tea plants, responsible for the exotictaste of green tea. We investigated the effects of relate to relaxation, improves the taste of processed foods, radiation sensitization, and increase of body surface temperature in vivo study. The results of the present study confirmed, (1) Suntheanine is incorporated into the brain and induces the emission of α -waves an induced of relaxation. (2) Body surface temperature and blood flow on skin were increased after administration of Suntheanine. (3) There was effects of radiation sensitization in whole body irradiation of X-rays after Suntheanine IP injection on C3H mice. (4) Acute toxicity, subacute toxicity and mutagen testconfirm the safety Suntheanine in this study

  2. Non-integrability of geodesic flow on certain algebraic surfaces

    International Nuclear Information System (INIS)

    Waters, T.J.

    2012-01-01

    This Letter addresses an open problem recently posed by V. Kozlov: a rigorous proof of the non-integrability of the geodesic flow on the cubic surface xyz=1. We prove this is the case using the Morales–Ramis theorem and Kovacic algorithm. We also consider some consequences and extensions of this result. -- Highlights: ► The behaviour of geodesics on surfaces defined by algebraic expressions is studied. ► The non-integrability of the geodesic equations is rigorously proved using differential Galois theory. ► Morales–Ramis theory and Kovacic's algorithm is used and the normal variational equation is of Fuchsian type. ► Some extensions and limitations are discussed.

  3. SIPSON--simulation of interaction between pipe flow and surface overland flow in networks.

    Science.gov (United States)

    Djordjević, S; Prodanović, D; Maksimović, C; Ivetić, M; Savić, D

    2005-01-01

    The new simulation model, named SIPSON, based on the Preissmann finite difference method and the conjugate gradient method, is presented in the paper. This model simulates conditions when the hydraulic capacity of a sewer system is exceeded, pipe flow is pressurized, the water flows out from the piped system to the streets, and the inlets cannot capture all the runoff. In the mathematical model, buried structures and pipelines, together with surface channels, make a horizontally and vertically looped network involving a complex interaction of flows. In this paper, special internal boundary conditions related to equivalent inlets are discussed. Procedures are described for the simulation of manhole cover loss, basement flooding, the representation of street geometry, and the distribution of runoff hydrographs between surface and underground networks. All these procedures are built into the simulation model. Relevant issues are illustrated on a set of examples, focusing on specific parameters and comparison with field measurements of flooding of the Motilal ki Chal catchment (Indore, India). Satisfactory agreement of observed and simulated hydrographs and maximum surface flooding levels is obtained. It is concluded that the presented approach is an improvement compared to the standard "virtual reservoir" approach commonly applied in most of the models.

  4. Evaluation method for core thermohydraulics during natural circulation in fast reactors numerical predictions of inter-wrapper flow

    International Nuclear Information System (INIS)

    Kamide, H.; Kimura, N.; Miyakoshi, H.; Nagasawa, K.

    2001-01-01

    Decay heat removal using natural circulation is one of the important functions for the safety of fast reactors. As a decay heat removal system, direct reactor auxiliary cooling system has been selected in current designs of fast reactors. In this design, dumped heat exchanger provides cold sodium and it covers the reactor core outlet. The cold sodium can penetrate into the gap region between the subassemblies. This gap flow is referred as inter-wrapper flow (IWF). A numerical estimation method for such natural circulation phenomena in a reactor core has been developed, which models each subassembly as a rectangular duct with gap region between the subassemblies and also the upper plenum in a reactor vessel. This numerical simulation method was verified based on experimental data of a sodium test using 7- subassembly core model and also a water test which simulates IWF using the 1/12 sector model of a reactor core. We applied the estimation method to the natural circulation in a 600 MW class fast reactor. The temperature in the core strongly depended on IWF, flow redistribution in the core, and inter-subassembly heat transfer. It is desired for prediction methods on the natural circulation to simulate these phenomena. (author)

  5. Contribution to the physical validation of computer programs for reactor cores flows

    International Nuclear Information System (INIS)

    Bourgeois, Pierre

    1998-01-01

    A κ-ε turbulence model was implemented in the FLICA computer code which is devoted to thermal-hydraulic analysis of nuclear reactor cores flows. Foreseen applications concern single-phase flows in rod bundles. First-moment closure principles are reminded. Low Reynolds wall effects are accounted for by a two-layer approach. A computational method for the distance from the wall must have been developed to do so. Two two-layer κ-ε models are proposed and studied: the classical isotropic version, based on the Boussinesq's hypothesis, and an original anisotropic version which supposes a non-linear relation between Reynolds stresses and mean deformation rate. The second one permits the treatment of anisotropy, which is encountered in non-circular ducts in general, and in rod bundles in particular. Turbulent solver is linearized implicit, based on a finite volume method - VF9 scheme for the viscous part, upwind scheme for passive scalar for the convective part, centered scheme for the source terms. Several numerical simulations on 2D and 3D configurations were conducted (validation standard test, industrial application). (author) [fr

  6. Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles.

    Science.gov (United States)

    Dzimitrowicz, Anna; Jamroz, Piotr; Nyk, Marcin; Pohl, Pawel

    2016-04-06

    A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO₃ solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system.

  7. 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.

  8. Predictive model for convective flows induced by surface reactivity contrast

    Science.gov (United States)

    Davidson, Scott M.; Lammertink, Rob G. H.; Mani, Ali

    2018-05-01

    Concentration gradients in a fluid adjacent to a reactive surface due to contrast in surface reactivity generate convective flows. These flows result from contributions by electro- and diffusio-osmotic phenomena. In this study, we have analyzed reactive patterns that release and consume protons, analogous to bimetallic catalytic conversion of peroxide. Similar systems have typically been studied using either scaling analysis to predict trends or costly numerical simulation. Here, we present a simple analytical model, bridging the gap in quantitative understanding between scaling relations and simulations, to predict the induced potentials and consequent velocities in such systems without the use of any fitting parameters. Our model is tested against direct numerical solutions to the coupled Poisson, Nernst-Planck, and Stokes equations. Predicted slip velocities from the model and simulations agree to within a factor of ≈2 over a multiple order-of-magnitude change in the input parameters. Our analysis can be used to predict enhancement of mass transport and the resulting impact on overall catalytic conversion, and is also applicable to predicting the speed of catalytic nanomotors.

  9. Localized reactive flow in carbonate rocks: Core-flood experiments and network simulations

    Science.gov (United States)

    Wang, Haoyue; Bernabé, Yves; Mok, Ulrich; Evans, Brian

    2016-11-01

    We conducted four core-flood experiments on samples of a micritic, reef limestone from Abu Dhabi under conditions of constant flow rate. The pore fluid was water in equilibrium with CO2, which, because of its lowered pH, is chemically reactive with the limestone. Flow rates were between 0.03 and 0.1 mL/min. The difference between up and downstream pore pressures dropped to final values ≪1 MPa over periods of 3-18 h. Scanning electron microscope and microtomography imaging of the starting material showed that the limestone is mostly calcite and lacks connected macroporosity and that the prevailing pores are few microns large. During each experiment, a wormhole formed by localized dissolution, an observation consistent with the decreases in pressure head between the up and downstream reservoirs. Moreover, we numerically modeled the changes in permeability during the experiments. We devised a network approach that separated the pore space into competing subnetworks of pipes. Thus, the problem was framed as a competition of flow of the reactive fluid among the adversary subnetworks. The precondition for localization within certain time is that the leading subnetwork rapidly becomes more transmissible than its competitors. This novel model successfully simulated features of the shape of the wormhole as it grew from few to about 100 µm, matched the pressure history patterns, and yielded the correct order of magnitude of the breakthrough time. Finally, we systematically studied the impact of changing the statistical parameters of the subnetworks. Larger mean radius and spatial correlation of the leading subnetwork led to faster localization.

  10. Continuous vs. pulsating flow boiling. Part 2: Statistical comparison using response surface methodology

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2016-01-01

    Response surface methodology is used to investigate an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The flow pulsations are introduced by a flow modulating expansion device and compared with the baseline continuous flow provided by a stepper...

  11. Analysis of two-phase flow and boiling heat transfer in inclined channel of core-catcher

    International Nuclear Information System (INIS)

    Tahara, M.; Suzuki, Y.; Abe, N.; Kurita, T.; Hamazaki, R.; Kojima, Y.

    2008-01-01

    Passive Corium Cooling System (CCS) provides a function of ex-vessel debris cooling and molten core stabilization during a severe accident. CCS features inclined cooling channels arranged axi-symmetrically below the core-catcher basin. In order to estimate the coolability of the inclined cooling channel, it is indispensable to identify the flow pattern of the two-phase flow in the cooling channel. Several former studies for the two-phase flow pattern in the inclined channel are referred. Taitel and Dukler (1976) developed a prediction method of the flow pattern transition in horizontal and near horizontal tubes. Barnea et al. (1980) showed the flow pattern map of upward flow with 10 degrees inclination. Sakaguti et al. (1996) observed the two-phase flow patterns in the horizontal pipe connected with slightly upward pipe, in which the flow pattern in the pipe with a bending part was expressed by the combination of a basic flow pattern and some auxiliary flow patterns. Then we investigated these studies In order to identify the flow patterns observed in the inclined cooling channel of CCS. Furthermore we experimentally observed the flow patterns in the inclined cooling channel with various inlet conditions. As a result of the investigation and observation, typical flow patterns in the inclined cooling channel were identified. Two typical flow patterns were observed depending on the steam flow rate, one of which is 'elongated bubble 'flow, and the other is 'churn with collapsing backward and upward slug 'flow The flow and heat transfer in the inclined channel of CCS is analyzed by using a two-phase analysis code employing two-fluid model in which the constitutive equations for the two-phase flow in inclined channels are incorporated. That is, drift flux parameter for each of the elongated bubble flow, and the churn with collapsing backward and upward slug flow are incorporated to the two-phase analysis code, which are based on the rising velocity of the long bubble in

  12. Influence of ecologically friendly cores on surface quality of castings based on magnesium alloys

    Directory of Open Access Journals (Sweden)

    P. Lichý

    2014-07-01

    Full Text Available Constructional materials as Al - alloys can be replaced by other materials with high strength to low mass density ratio, e.g. Mg-alloys. In order to pre-casting of holes and cavities cores based on pure inorganic salt can be applied due to easy cleaning of even geometrically complex pre-cast holes. This technology is applied mainly for gravity and low-pressure casting technology. This contribution is aimed at studying of mutual interaction of the Mg-alloy and the salt core. Experiments were focused on surface quality; macro- and microstructure of testing casting samples determination. Metallographic analysis and scanning electron microscope (SEM with X-ray energy-dispersion superficial and spot microanalysis (EDAX were employed.

  13. Hollow-Core Photonic Crystal Fibers for Surface-Enhanced Raman Scattering Probes

    Directory of Open Access Journals (Sweden)

    Xuan Yang

    2011-01-01

    Full Text Available Photonic crystal fiber (PCF sensors based on surface-enhanced Raman scattering (SERS have become increasingly attractive in chemical and biological detections due to the molecular specificity, high sensitivity, and flexibility. In this paper, we review the development of PCF SERS sensors with emphasis on our recent work on SERS sensors utilizing hollow-core photonic crystal fibers (HCPCFs. Specifically, we discuss and compare various HCPCF SERS sensors, including the liquid-filled HCPCF and liquid-core photonic crystal fibers (LCPCFs. We experimentally demonstrate and theoretically analyze the high sensitivity of the HCPCF SERS sensors. Various molecules including Rhodamine B, Rhodamine 6G, human insulin, and tryptophan have been tested to show the excellent performance of these fiber sensors.

  14. Surface studies of water isotopes in Antarctica for quantitative interpretation of deep ice core data

    Science.gov (United States)

    Landais, Amaelle; Casado, Mathieu; Prié, Frédéric; Magand, Olivier; Arnaud, Laurent; Ekaykin, Alexey; Petit, Jean-Robert; Picard, Ghislain; Fily, Michel; Minster, Bénédicte; Touzeau, Alexandra; Goursaud, Sentia; Masson-Delmotte, Valérie; Jouzel, Jean; Orsi, Anaïs

    2017-07-01

    Polar ice cores are unique climate archives. Indeed, most of them have a continuous stratigraphy and present high temporal resolution of many climate variables in a single archive. While water isotopic records (δD or δ18O) in ice cores are often taken as references for past atmospheric temperature variations, their relationship to temperature is associated with a large uncertainty. Several reasons are invoked to explain the limitation of such an approach; in particular, post-deposition effects are important in East Antarctica because of the low accumulation rates. The strong influence of post-deposition processes highlights the need for surface polar research programs in addition to deep drilling programs. We present here new results on water isotopes from several recent surface programs, mostly over East Antarctica. Together with previously published data, the new data presented in this study have several implications for the climatic reconstructions based on ice core isotopic data: (1) The spatial relationship between surface mean temperature and mean snow isotopic composition over the first meters in depth can be explained quite straightforwardly using simple isotopic models tuned to d-excess vs. δ18O evolution in transects on the East Antarctic sector. The observed spatial slopes are significantly higher (∼ 0.7-0.8‰·°C-1 for δ18O vs. temperature) than seasonal slopes inferred from precipitation data at Vostok and Dome C (0.35 to 0.46‰·°C-1). We explain these differences by changes in condensation versus surface temperature between summer and winter in the central East Antarctic plateau, where the inversion layer vanishes in summer. (2) Post-deposition effects linked to exchanges between the snow surface and the atmospheric water vapor lead to an evolution of δ18O in the surface snow, even in the absence of any precipitation event. This evolution preserves the positive correlation between the δ18O of snow and surface temperature, but is

  15. Modelling of a free-surface ferrofluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Habera, M., E-mail: habera@karlin.mff.cuni.cz; Hron, J., E-mail: hron@karlin.mff.cuni.cz

    2017-06-01

    The Cauchy's stress tensor of a ferrofluid exposed to an external magnetic field is subject to additional magnetic terms. For a linearly magnetizable medium, the terms result in interfacial magnetic force acting on the ferrofluid boundaries. This force changes the characteristics of many free-surface ferrofluid phenomena. The aim of this work is to implement this force into the incompressible Navier-Stokes equations and propose a numerical method to solve them. The interface of ferrofluid is tracked with the use of the characteristic level-set method and additional reinitialization step assures conservation of its volume. Incompressible Navier-Stokes equations are formulated for a divergence-free velocity fields while discrete interfacial forces are treated with continuous surface force model. Velocity-pressure coupling is implemented via the projection method. To predict the magnetic force effect quantitatively, Maxwell's equations for magnetostatics are solved in each time step. Finite element method is utilized for the spatial discretization. At the end of the work, equilibrium droplet shape are compared to known experimental results. - Highlights: • Incompressible Navier-Stokes equations are formulated for the problem of free-surface ferrofluid flow. • Computed equilibrium ferrofluid droplet shape is compared to known experimental result. • Magnetic field substantially changes the dynamics of ferrofluid dripping process.

  16. Frost Growth and Densification in Laminar Flow Over Flat Surfaces

    Science.gov (United States)

    Kandula, Max

    2011-01-01

    One-dimensional frost growth and densification in laminar flow over flat surfaces has been theoretically investigated. Improved representations of frost density and effective thermal conductivity applicable to a wide range of frost circumstances have been incorporated. The validity of the proposed model considering heat and mass diffusion in the frost layer is tested by a comparison of the predictions with data from various investigators for frost parameters including frost thickness, frost surface temperature, frost density and heat flux. The test conditions cover a range of wall temperature, air humidity ratio, air velocity, and air temperature, and the effect of these variables on the frost parameters has been exemplified. Satisfactory agreement is achieved between the model predictions and the various test data considered. The prevailing uncertainties concerning the role air velocity and air temperature on frost development have been elucidated. It is concluded that that for flat surfaces increases in air velocity have no appreciable effect on frost thickness but contribute to significant frost densification, while increase in air temperatures results in a slight increase the frost thickness and appreciable frost densification.

  17. BWR core response to fluctuations in coolant flow and pressure, with implications on noise diagnosis and stability monitoring

    International Nuclear Information System (INIS)

    Blomstrand, J.H.; Andersson, S.A.

    1982-01-01

    Reactor dynamic tests, utilizing sinuosidal oscillations in pressure and recirculation flow, have been conducted in operating BWRs in Sweden and Finland. Test data recorded, as well as recordings of process noise, have been analyzed in terms of dynamic core properties. The results obtained show good qualitative agreement with model predictions of BWR core dynamics. Model studies can often support interpretation of dynamic information obtained from operating plants. Comparisons between model studies, dynamic tests and process noise may also provide improved understanding of test results and noise patterns; in this way it can be demonstrated that some neutron flux noise is caused by noise in coolant flow and steam flow. From reactor test data nd noise recordings, core stability parameters have been evaluated by a number of methods. These have been found to provide essentially the same results. The cores investigated were found to be very stable under normal operating conditions. In special operating points, outside the normal operating range, higher decay ratios may occur. The experience indicates that for BWR cores, operated at decay ratios above quarter damping, the stability parameters may be identified from the oscillatory behavior of the autocorrelation in the time domain of the neutron flux noise

  18. Role of wall-attached structures in the interface of the quiescent core region in turbulent pipe flow

    Science.gov (United States)

    Yang, Jongmin; Hwang, Jinyul; Sung, Hyung Jin

    2017-11-01

    The effects of low- and high-speed structures on the interface of the quiescent core region are explored using direct numerical simulation data of turbulent pipe flow. The quiescent core region is a uniform momentum zone located at the center of the pipe flow, which contains the highest streamwise momentum with a low level of turbulence. The interface of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. In the vicinity of the interface of the quiescent core region, the streamwise velocity changes abruptly. The abrupt jump in velocity causes an increase of the velocity gradient. The interface of the quiescent core region is similar to the laminar superlayer in turbulent/non-turbulent interface. The interface of the quiescent core region contains the low- and high-speed structures. They can be classified into wall-attached and detached structures depending on the distance between the structures and the wall. The influence of the detached structures accounted for most of the number of detected structures is negligible due to its small volume. Conversely, the wall-attached structures adjacent to the interface have a huge influence on the statistical amount of the interface, such as entrainment characteristics. This work was supported by the Creative Research Initiatives (No. 2017-013369) program of the National Research Foundation of Korea (MSIP).

  19. Mineral and chemical composition of rock core and surface gas composition in Horonobe Underground Research Laboratory project. Phase 1

    International Nuclear Information System (INIS)

    Hiraga, Naoto; Ishii, Eiichi

    2008-02-01

    The following three kinds of analyses were conducted for the 1st phase of the Horonobe Underground Research Laboratory Project. Mineral composition analysis of core sample. Whole rock chemical composition analysis of core sample. Surface gas composition analysis. This document summarizes the results of these analyses. (author)

  20. DNS of flows over superhydrophobic surfaces with small texture

    Science.gov (United States)

    Fairhall, Chris; Garcia-Mayoral, Ricardo

    2015-11-01

    We present results from direct numerical simulations of turbulent flows over superhydrophobic surfaces with small texture sizes, comparable to those of practical application. Textures studied with DNS are usually much larger, as the cost of the simulations would otherwise be prohibitive. For this reason, a multi-block code that allows for finer resolution near the walls has been developed. We focus particularly on the pressure distribution at the wall. This distribution can cause the deformation of the gas pockets, which can ultimately lead to their loss and that of the drag reduction effect. The layout of the texture causes stagnation pressures which can contribute substantially to the wall pressure signal (Seo et al. JFM, under review). We study a range of different textures and their influence on these pressures.

  1. Core fracture analysis applied to ground water flow systems: Chickamauga Group, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Bittner, E.; Dreier, R.B.

    1989-01-01

    The objective of this study is to correlate hydrologic properties with detailed geologic fabrics and to investigate the influence of a complex geologic setting on ground water systems. The Chickamauga Group (CH) located in Bethel Valley on the DOE Oak Ridge Reservation is comprised of limestones and interbedded shales. Five core holes (CH 1-5), oriented across strike, provide a cross section of the CH and were mapped for fracture density, orientation and cross-cutting relationships as well as lithologic variations. Correlation of structural and lithologic features with downhole geophysical logs and hydraulic conductivity values shows a relationship between lithology, fracture density and increased permeability in an otherwise low-permeability environment. Structures identified as influential in enhancing hydraulic conductivity include contractional bedding plane and tectonic stylolites and extensional fractures. Three sets of extensional fractures are indicated by cross-cutting relationships and various degrees of veining. Hydraulic conductivity values (K) for the five wells indicate two ground water flow systems in the valley. A shallow system (up to 150 feet deep) shows a range in K from 10E-4 centimeters per second to 10E-6 centimeters per second. Shallow horizons show more open fractures than are observed at depth, and these fractures appear to control the enhanced K in the shallow system. A subhorizontal interface that is not defined by pre-existing structures or a stratigraphic horizon separates the two flow systems. The deeper system ranges in K values from 10E-9 centimeters per second to 10E-5 centimeters per second. The higher K values at depth correspond to increased fracture density at lithologic contacts, zones of tectonic stylolitization and partially veined extension fractures. 11 refs., 11 figs., 2 tabs

  2. CFD analysis of flow distribution of reactor core and temperature rise of coolant in fuel assembly for VVER reactor

    International Nuclear Information System (INIS)

    Du Daiquan; Zeng Xiaokang; Xiong Wanyu; Yang Xiaoqiang

    2015-01-01

    Flow field of VVER-1000 reactor core was investigated by using computational fluid dynamics code CFX, and the temperature rise of coolant in hot assembly was calculated. The results show that the maximum value of flow distribution factor is 1.12 and the minimum value is 0.92. The average value of flow distribution factor in hot assembly is 0.97. The temperature rise in hot assembly is higher than current warning limit value ΔT t under the deviated operation condition. The results can provide reference for setting ΔT t during the operation of nuclear power plant. (authors)

  3. Localized surface plasmon mediated energy transfer in the vicinity of core-shell nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Shishodia, Manmohan Singh, E-mail: manmohan@gbu.ac.in; Juneja, Soniya [Department of Applied Physics, School of Vocational Studies and Applied Sciences, Gautam Buddha University, Greater Noida 201308 (India)

    2016-05-28

    Multipole spectral expansion based theory of energy transfer interactions between a donor and an acceptor molecule in the vicinity of a core-shell (nanoshell or core@shell) based plasmonic nanostructure is developed. In view of the diverse applications and rich plasmonic features such as tuning capability of surface plasmon (SP) frequencies, greater sensitivity to the change of dielectric environment, controllable redirection of electromagnetic radiation, closed form expressions for Energy Transfer Rate Enhancement Factor (ETREF) near core-shell particle are reported. The dependence of ETREF on different parameters is established through fitting equations, perceived to be of key importance for developing appropriate designs. The theoretical approach developed in the present work is capable of treating higher order multipoles, which, in turn, are also shown to play a crucial role in the present context. Moreover, closed form expressions derived in the present work can directly be used as formula, e.g., for designing SP based biosensors and estimating energy exchange between proteins and excitonic interactions in quantum dots.

  4. Why is Facebook so successful? Psychophysiological measures describe a core flow state while using Facebook.

    Science.gov (United States)

    Mauri, Maurizio; Cipresso, Pietro; Balgera, Anna; Villamira, Marco; Riva, Giuseppe

    2011-12-01

    People are more and more using social networking sites (SNSs) like Facebook and MySpace to engage with others. The use of SNSs can have both positive and negative effect on the individual; however, the increasing use of SNSs might reveal that people look for SNSs because they have a positive experience when they use them. Few studies have tried to identify which particular aspects of the social networking experience make SNSs so successful. In this study we focus on the affective experience evoked by SNSs. In particular, we explore whether the use of SNSs elicits a specific psychophysiological pattern. Specifically, we recorded skin conductance, blood volume pulse, electroencephalogram, electromyography, respiratory activity, and pupil dilation in 30 healthy subjects during a 3-minute exposure to (a) a slide show of natural panoramas (relaxation condition), (b) the subject's personal Facebook account, and (c) a Stroop and mathematical task (stress condition). Statistical analysis of the psychophysiological data and pupil dilation indicates that the Facebook experience was significantly different from stress and relaxation on many linear and spectral indices of somatic activity. Moreover, the biological signals revealed that Facebook use can evoke a psychophysiological state characterized by high positive valence and high arousal (Core Flow State). These findings support the hypothesis that the successful spread of SNSs might be associated with a specific positive affective state experienced by users when they use their SNSs account.

  5. Towards an integrated petrophysical tool for multiphase flow properties of core samples

    Energy Technology Data Exchange (ETDEWEB)

    Lenormand, R. [Institut Francais du Petrole, Rueil Malmaison (France)

    1997-08-01

    This paper describes the first use of an Integrated Petrophysical Tool (IPT) on reservoir rock samples. The IPT simultaneously measures the following petrophysical properties: (1) Complete capillary pressure cycle: primary drainage, spontaneous and forced imbibitions, secondary drainage (the cycle leads to the wettability of the core by using the USBM index); End-points and parts of the relative permeability curves; Formation factor and resistivity index. The IPT is based on the steady-state injection of one fluid through the sample placed in a Hassler cell. The experiment leading to the whole Pc cycle on two reservoir sandstones consists of about 30 steps at various oil or water flow rates. It takes about four weeks and is operated at room conditions. Relative permeabilities are in line with standard steady-state measurements. Capillary pressures are in accordance with standard centrifuge measurements. There is no comparison for the resistivity index, but the results are in agreement with literature data. However, the accurate determination of saturation remains the main difficulty and some improvements are proposed. In conclusion, the Integrated Petrophysical Tool is as accurate as standard methods and has the advantage of providing the various parameters on the same sample and during a single experiment. The FIT is easy to use and can be automated. In addition, it can be operated in reservoir conditions.

  6. Interactions of solitary waves and compression/expansion waves in core-annular flows

    Science.gov (United States)

    Maiden, Michelle; Anderson, Dalton; El, Gennady; Franco, Nevil; Hoefer, Mark

    2017-11-01

    The nonlinear hydrodynamics of an initial step leads to the formation of rarefaction waves and dispersive shock waves in dispersive media. Another hallmark of these media is the soliton, a localized traveling wave whose speed is amplitude dependent. Although compression/expansion waves and solitons have been well-studied individually, there has been no mathematical description of their interaction. In this talk, the interaction of solitons and shock/rarefaction waves for interfacial waves in viscous, miscible core-annular flows are modeled mathematically and explored experimentally. If the interior fluid is continuously injected, a deformable conduit forms whose interfacial dynamics are well-described by a scalar, dispersive nonlinear partial differential equation. The main focus is on interactions of solitons with dispersive shock waves and rarefaction waves. Theory predicts that a soliton can either be transmitted through or trapped by the extended hydrodynamic state. The notion of reciprocity is introduced whereby a soliton interacts with a shock wave in a reciprocal or dual fashion as with the rarefaction. Soliton reciprocity, trapping, and transmission are observed experimentally and are found to agree with the modulation theory and numerical simulations. This work was partially supported by NSF CAREER DMS-1255422 (M.A.H.) and NSF GRFP (M.D.M.).

  7. 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.

  8. A Prototype Flux-Plate Heat-Flow Sensor for Venus Surface Heat-Flow Determinations

    Science.gov (United States)

    Morgan, Paul; Reyes, Celso; Smrekar, Suzanne E.

    2005-01-01

    Venus is the most Earth-like planet in the Solar System in terms of size, and the densities of the two planets are almost identical when selfcompression of the two planets is taken into account. Venus is the closest planet to Earth, and the simplest interpretation of their similar densities is that their bulk compositions are almost identical. Models of the thermal evolution of Venus predict interior temperatures very similar to those indicated for the regions of Earth subject to solid-state convection, but even global analyses of the coarse Pioneer Venus elevation data suggest Venus does not lose heat by the same primary heat loss mechanism as Earth, i.e., seafloor spreading. The comparative paucity of impact craters on Venus has been interpreted as evidence for relatively recent resurfacing of the planet associated with widespread volcanic and tectonic activity. The difference in the gross tectonic styles of Venus and Earth, and the origins of some of the enigmatic volcano-tectonic features on Venus, such as the coronae, appear to be intrinsically related to Venus heat loss mechanism(s). An important parameter in understanding Venus geological evolution, therefore, is its present surface heat flow. Before the complications of survival in the hostile Venus surface environment were tackled, a prototype fluxplate heat-flow sensor was built and tested for use under synthetic stable terrestrial surface conditions. The design parameters for this prototype were that it should operate on a conforming (sand) surface, with a small, self-contained power and recording system, capable of operating without servicing for at least several days. The precision and accuracy of the system should be < 5 mW/sq m. Additional information is included in the original extended abstract.

  9. Measurement of two-phase flow variables in a BWR by analysis of in-core neutron detector noise signals

    International Nuclear Information System (INIS)

    Stekelenburg, A.J.C.; Hagen, T.H.J.J. van der

    1996-01-01

    In this paper, the state of the art of the measurement of two-phase flow variables in a boiling water reactor (BWR) by analysis of in-core neutron detector noise signals is given. It is concluded that the neutronic processes involved in neutron noise are quite well understood, but that little is known about the density fluctuations in two-phase flow which are the main cause of the neutron noise. For this reason, the neutron noise measurements, like the well known two-detector velocity measurements, are still difficult to interpret. By analyzing neutron noise measurements in a natural circulation cooled BWR, it is illustrated that, once a theory on the density fluctuations is developed, two-phase flow can be monitored with a single in-core detector. (author). 70 refs, 4 figs

  10. Free-surface entrainment into a rimming flow containing surfactants

    Science.gov (United States)

    Thoroddsen, S. T.; Tan, Y.-K.

    2004-02-01

    We study experimentally the free-surface entrainment of tubes into a steady rimming flow formed inside a partially filled horizontally rotating cylinder. The liquid consists of a glycerin-water mixture containing surfactants (fatty acids). The phenomenon does not occur without the surfactants and the details are sensitive to their concentration. The entrainment of numerous closely spaced air tubes and/or surfactant columns can start intermittently along a two-dimensional stagnation line, but is usually associated with the appearance of an axially periodic vortex structure, the so-called shark teeth, which fixes the spanwise location of these tubes. The number of tubes is governed by the three-dimensional shape of the free surface, reducing from more than 10 to only two in each trough, as the rotation rate is increased. The tubes vary in diameter from 10-30 μm and can extend hundreds of diameters into the liquid layer before breaking up into a continuous stream of bubbles and/or drops. The tubes are driven through the stagnation line by the strong viscous shear and are stretched in the downstream direction. The entrainment starts when the Capillary number Ca=μωR/σ≃0.4.

  11. Free Surface Flows and Extensional Rheology of Polymer Solutions

    Science.gov (United States)

    Dinic, Jelena; Jimenez, Leidy Nallely; Biagioli, Madeleine; Estrada, Alexandro; Sharma, Vivek

    Free-surface flows - jetting, spraying, atomization during fuel injection, roller-coating, gravure printing, several microfluidic drop/particle formation techniques, and screen-printing - all involve the formation of axisymmetric fluid elements that spontaneously break into droplets by a surface-tension-driven instability. The growth of the capillary-driven instability and pinch-off dynamics are dictated by a complex interplay of inertial, viscous and capillary stresses for simple fluids. Additional contributions by elasticity, extensibility and extensional viscosity play a role for complex fluids. We show that visualization and analysis of capillary-driven thinning and pinch-off dynamics of the columnar neck in an asymmetric liquid bridge created by dripping-onto-substrate (DoS) can be used for characterizing the extensional rheology of complex fluids. Using a wide variety of complex fluids, we show the measurement of the extensional relaxation time, extensional viscosity, power-law index and shear viscosity. Lastly, we elucidate how polymer composition, flexibility, and molecular weight determine the thinning and pinch-off dynamics of polymeric complex fluids.

  12. Solid-Core, Gas-Cooled Reactor for Space and Surface Power

    International Nuclear Information System (INIS)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2006-01-01

    The solid-core, gas-cooled, Submersion-Subcritical Safe Space (S and 4) reactor is developed for future space power applications and avoidance of single point failures. The Mo-14%Re reactor core is loaded with uranium nitride fuel in enclosed cavities, cooled by He-30%Xe, and sized to provide 550 kWth for seven years of equivalent full power operation. The beryllium oxide reflector disassembles upon impact on water or soil. In addition to decreasing the reactor and shadow shield mass, Spectral Shift Absorber (SSA) materials added to the reactor core ensure that it remains subcritical in the worst-case submersion accident. With a 0.1 mm thick boron carbide coating on the outside surface of the core block and 0.25 mm thick iridium sleeves around the fuel stacks, the reflector outer diameter is 43.5 cm and the combined reactor and shadow shield mass is 935.1 kg. With 12.5 atom% gadolinium-155 added to the fuel, 2.0 mm diameter gadolinium-155 sesquioxide intersititial pins, and a 0.1 mm thick gadolinium-155 sesquioxide coating, the S and 4 reactor has a slightly smaller reflector outer diameter of 43.0 cm, and a total reactor and shield mass of 901.7 kg. With 8.0 atom% europium-151 added to the fuel, 2.0 mm diameter europium-151 sesquioxide interstitial pins, and a 0.1 mm thick europium-151 sesquioxide coating, the reflector's outer diameter and the total reactor and shield mass are further reduced to 41.5 cm and 869.2 kg, respectively

  13. Prediction, analysis and solution of flow inversion phenomenon in a typical MTR reactor with upward core cooling

    International Nuclear Information System (INIS)

    El-Morshedy, Salah El-Din

    2010-01-01

    Research reactors of power greater than 20 MW are usually designed to be cooled with upward coolant flow direction inside the reactor core. This is mainly to prevent flow inversion problems following a pump coast down. However, in some designs and under certain operating conditions, flow inversion phenomenon is predicted. In the present work, the best-estimate Material Testing Reactors Thermal-Hydraulic Analysis program (MTRTHA) is used to simulate a typical MTR reactor behavior with upward cooling under a hypothetical case of loss of off-site power. The flow inversion phenomenon is predicted under certain decay heat and/or pool temperature values below the design values. The reactor simulation under loss of off-site power is performed for two cases namely; two-flap valves open and one flap-valve fails to open. The model results for the flow inversion phenomenon prediction is analyzed and a solution of the problem is suggested. (orig.)

  14. Simple and convenient preparation of Au-Pt core-shell nanoparticles on surface via a seed growth method

    International Nuclear Information System (INIS)

    Qian Lei; Sha Yufang; Yang Xiurong

    2006-01-01

    Au-Pt core-shell nanoparticles were prepared on glass surface by a seed growth method. Gold nanoparticles were used as seeds and ascorbic acid-H 2 PtCl 6 solutions as growth solutions to deposit Pt shell on the surface of gold nanoparticles. These core-shell nanoparticles and their growth process were examined by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and field-emission environmental scanning electron microscopy and the results indicated that the deposition speed was fast and nanoparticles with obvious core-shell structure could be obtained after 2 min. Moreover, this seed growth method for preparation of the core-shell nanoparticles is simple and convenient compared with other seed growth methods with NH 4 OH as a mild reductant. In addition, electrochemical experiments indicated that these Au-Pt core-shell nanoparticles had similar electrochemical properties to those of the bulk Pt electrode

  15. Two-phase flow pattern and heat transfer during core uncovery

    International Nuclear Information System (INIS)

    Osakabe, Masahiro; Koizumi, Yasuo; Tasaka, Kanji

    1987-01-01

    The low and high power core uncovery patterns were observed in the high-pressure quasi-steady core uncovery experiments in a 25-rod bundle. The boundary between the two patterns was obtained in the experiments. The difference of two patterns was considered to be due to the slug-annular transition below the dryout points. The Osakabe's slug-annular transition model was the good boundary between the two patterns. The small break loss-of-coolant accident (LOCA) experiments were conducted by using the integral experimental facility with the 1,168-rod core. The transient core uncovery pattern was expected as the low power core uncovery pattern based on the quasisteady experiments mentioned above. The transient core uncovery patterns were classified into the boiloff and hydraulic core uncovery. In the boiloff core uncovery, the dryout points were controlled with the mixture level like the quasi-steady state. In the hydraulic core uncovery, the dryout points were not controlled with the mixture level alone, and the multi-dimensional dryout process in the core and the relatively high heat transfer above the dryout points were observed. It was considered that a part of water was remained above the dryout points due to the rapid depression of core liquid level. (author)

  16. Correction for Delay and Dispersion Results in More Accurate Cerebral Blood Flow Ischemic Core Measurement in Acute Stroke.

    Science.gov (United States)

    Lin, Longting; Bivard, Andrew; Kleinig, Timothy; Spratt, Neil J; Levi, Christopher R; Yang, Qing; Parsons, Mark W

    2018-04-01

    This study aimed to assess how the ischemic core measured by perfusion computed tomography (CTP) was affected by the delay and dispersion effect. Ischemic stroke patients having CTP performed within 6 hours of onset were included. The CTP data were processed twice, generating standard cerebral blood flow (sCBF) and delay- and dispersion-corrected CBF (ddCBF), respectively. Ischemic core measured by the sCBF and ddCBF was then compared at the relative threshold core were used: acute diffusion-weighted imaging or 24-hour diffusion-weighted imaging in patients with complete recanalization. Difference of core volume between CTP and diffusion-weighted imaging was estimated by Mann-Whitney U test and limits of agreement. Patients were also classified into favorable and unfavorable CTP patterns. The imaging pattern classification by sCBF and ddCBF was compared by the χ 2 test; their respective ability to predict good clinical outcome (3-month modified Rankin Scale score) was tested in logistic regression. Fifty-five patients were included in this study. Median sCBF ischemic core volume was 38.5 mL (12.4-61.9 mL), much larger than the median core volume of 17.2 mL measured by ddCBF (interquartile range, 5.5-38.8; P core much closer to diffusion-weighted imaging core references, with the mean volume difference of -0.1 mL (95% limits of agreement, -25.4 to 25.2; P =0.97) and 16.7 mL (95% limits of agreement, -21.7 to 55.2; P core measurement on CTP. © 2018 American Heart Association, Inc.

  17. Computational and Experimental Investigations of the Coolant Flow in the Cassette Fissile Core of a KLT-40S Reactor

    Science.gov (United States)

    Dmitriev, S. M.; Varentsov, A. V.; Dobrov, A. A.; Doronkov, D. V.; Pronin, A. N.; Sorokin, V. D.; Khrobostov, A. E.

    2017-07-01

    Results of experimental investigations of the local hydrodynamic and mass-exchange characteristics of a coolant flowing through the cells in the characteristic zones of a fuel assembly of a KLT-40S reactor plant downstream of a plate-type spacer grid by the method of diffusion of a gas tracer in the coolant flow with measurement of its velocity by a five-channel pneumometric probe are presented. An analysis of the concentration distribution of the tracer in the coolant flow downstream of a plate-type spacer grid in the fuel assembly of the KLT-40S reactor plant and its velocity field made it possible to obtain a detailed pattern of this flow and to determine its main mechanisms and features. Results of measurement of the hydraulic-resistance coefficient of a plate-type spacer grid depending on the Reynolds number are presented. On the basis of the experimental data obtained, recommendations for improvement of the method of calculating the flow rate of a coolant in the cells of the fissile core of a KLT-40S reactor were developed. The results of investigations of the local hydrodynamic and mass-exchange characteristics of the coolant flow in the fuel assembly of the KLT-40S reactor plant were accepted for estimating the thermal and technical reliability of the fissile cores of KLT-40S reactors and were included in the database for verification of computational hydrodynamics programs (CFD codes).

  18. Contribution to the modelling of flows and heat transfers during the reflooding phase of a PWR core

    International Nuclear Information System (INIS)

    Colas, D.

    1984-01-01

    This thesis contributes to modelise thermohydraulic phenomena occuring in a pressurized water nuclear reactor core during the reflood phase of a LOCA. The reference accident and phenomena occuring during reflooding are described as well as flow regime and heat transfer proposed models. With these models, we developed a code to compute fluid conditions and fuel rods temperatures in a reactor core chanel. In order to test this code, results of computation are compared with experiments (FLECHT Skewed Tests) and a conclusion is drawn [fr

  19. Free surface profiles in river flows: Can standard energy-based gradually-varied flow computations be pursued?

    Science.gov (United States)

    Cantero, Francisco; Castro-Orgaz, Oscar; Garcia-Marín, Amanda; Ayuso, José Luis; Dey, Subhasish

    2015-10-01

    Is the energy equation for gradually-varied flow the best approximation for the free surface profile computations in river flows? Determination of flood inundation in rivers and natural waterways is based on the hydraulic computation of flow profiles. This is usually done using energy-based gradually-varied flow models, like HEC-RAS, that adopts a vertical division method for discharge prediction in compound channel sections. However, this discharge prediction method is not so accurate in the context of advancements over the last three decades. This paper firstly presents a study of the impact of discharge prediction on the gradually-varied flow computations by comparing thirteen different methods for compound channels, where both energy and momentum equations are applied. The discharge, velocity distribution coefficients, specific energy, momentum and flow profiles are determined. After the study of gradually-varied flow predictions, a new theory is developed to produce higher-order energy and momentum equations for rapidly-varied flow in compound channels. These generalized equations enable to describe the flow profiles with more generality than the gradually-varied flow computations. As an outcome, results of gradually-varied flow provide realistic conclusions for computations of flow in compound channels, showing that momentum-based models are in general more accurate; whereas the new theory developed for rapidly-varied flow opens a new research direction, so far not investigated in flows through compound channels.

  20. Flow distribution experimental study on the emergency core cooling system of the IEA-R1m - IPEN-CNEN/SP - Brazil

    International Nuclear Information System (INIS)

    Torres, Walmir Maximo; Baptista Filho, Benedito Dias; Ting, Daniel Kao Sun

    1999-01-01

    This paper presents a brief description of Emergency Core Cooling System designed by the IEA-R1m Reactor and the experimental results of flow distribution over the core. Several parameters were evaluated, such as: relative position of spray header to the reactor core; type and quantity of spray nozzles; spray nozzles position on spray header; and total spray flow. The main conclusions are presented. (author)

  1. Experimental study of core thermohydraulics in fast reactors during transition from forced to natural circulation. Influence of inter-wrapper flow

    International Nuclear Information System (INIS)

    Kamide, H.; Hayashi, K.; Momoi, K.

    1997-01-01

    The evaluation of core thermohydraulics under natural circulation conditions is important to utilize inherent safety features of Fast Reactors. When heat exchangers of a decay heat removal system are operated in an upper plenum of reactor vessel, cold sodium is provided by the heat exchangers. Core-plenum interactions will occur during a natural circulation condition due to this cold sodium in the upper plenum, e.g., it can penetrate into gap regions between fuel subassemblies (inter-wrapper flow, IWF) and the flow may reverse in low power core channels. These interactions will significantly modify the flow and temperature distributions in the core. Sodium experiments were carried out to study these phenomena. In a test section, seven subassemblies are housed and connected to an upper plenum. The influences of core-plenum interactions on the core thermohydraulics were investigated under steady state conditions and also in transitions from forced to natural circulation. Cooling effects of IWF on the fuel subassemblies were found in spite of natural circulation flow reduction in the primary loop due to temperature decreases in the upper non-heated section in the core. The inter-wrapper flow can effectively cool the core under extreme conditions of low flow rates through the core. (author)

  2. Effects of confinement & surface roughness in electrorheological flows

    Science.gov (United States)

    Helal, Ahmed; Telleria, Maria J.; Wang, Julie; Strauss, Marc; Murphy, Mike; McKinley, Gareth; Hosoi, A. E.

    2014-11-01

    Electrorheological (ER) fluids are dielectric suspensions that exhibit a fast, reversible change in rheological properties with the application of an external electric field. Upon the application of the electric field, the material develops a field-dependent yield stress that is typically modeled using a Bingham plastic model. ER fluids are promising for designing small, cheap and rapidly actuated hydraulic devices such as rapidly-switchable valves, where fluid flowing in a microchannel can be arrested by applying an external electric field. In the lubrication limit, for a Bingham plastic fluid, the maximum pressure the channel can hold, before yielding, is a function of the field-dependent yield stress, the length of the channel and the electrode gap. In practice, the finite width of the channel and the surface roughness of the electrodes could affect the maximum yield pressure but a quantitative understanding of these effects is currently lacking. In this study, we experimentally investigate the effects of the channel aspect ratio (width/height) and the effects of electrode roughness on the performance of ER valves. Based on this quantitative analysis, we formulate new performance metrics for ER valves as well as design rules for ER valves that will help guide and optimize future designs.

  3. French experimental facilities for measurements of transverse flows and assessment of the corresponding risk of vibrations in heterogeneous cores

    International Nuclear Information System (INIS)

    Le Borgne, E.; Mattei, A.; Oceraies, Y.; Fardeau, P.

    1994-01-01

    Due to insertion of a limited number of new assemblies at each cycle, the cores in Pressurized Water Reactors are not homogeneous. Referring only to the impact on coolant flow, these differences can range from variable hydraulic resistances in the assembly, which depend on the geometric changes occurring during preceding cycles, to coexistence of assemblies with new design structures. Deviations in resistance between neighboring fuel assemblies causes the flow rates to be distributed differently between the assembly rods. This results in development of transverse flows from the main axial flow, and changes in the axial velocity gradients. These particularities of coolant flow have an effect on both vibration levels and cooling of the fuel rods, and also on the axial forces exerted on the assemblies in the core cavity. Since 1985, French Atomic Energy Commission (CEA) has gradually acquired experimental and measuring facilities that have allowed it to engage in research and development programs in these areas, in cooperation with industry partners in the nuclear field. Two complementary test loops have been constructed, called ARIANE and HERMES T. Use of these experimental facilities allows to obtain complete and detailed information on the hydraulic and vibratory phenomena specific to heterogeneous cores. In particular it is possible to establish a direct assessment of the actual compatibility between two different assemblies. By making a few specific changes, these facilities can also be used as a unique tool for assembly behaviour studies under seismic conditions with simulation of the flow effects. Also, a source of information in thus made available for qualification of computation codes for vibratory mechanics and multidimensional fluid mechanics under development at CEA and also used in the field of nuclear fuel. (authors). 6 figs., 1 ref

  4. Modeling sheet-flow sand transport under progressive surface waves

    NARCIS (Netherlands)

    Kranenburg, Wouter

    2013-01-01

    In the near-shore zone, energetic sea waves generate sheet-flow sand transport. In present day coastal models, wave-induced sheet-flow sand transport rates are usually predicted with semi-empirical transport formulas, based on extensive research on this phenomenon in oscillatory flow tunnels.

  5. Experimental calibration and validation of sewer/surface flow exchange equations in steady and unsteady flow conditions

    Science.gov (United States)

    Rubinato, Matteo; Martins, Ricardo; Kesserwani, Georges; Leandro, Jorge; Djordjević, Slobodan; Shucksmith, James

    2017-09-01

    The linkage between sewer pipe flow and floodplain flow is recognised to induce an important source of uncertainty within two-dimensional (2D) urban flood models. This uncertainty is often attributed to the use of empirical hydraulic formulae (the one-dimensional (1D) weir and orifice steady flow equations) to achieve data-connectivity at the linking interface, which require the determination of discharge coefficients. Because of the paucity of high resolution localised data for this type of flows, the current understanding and quantification of a suitable range for those discharge coefficients is somewhat lacking. To fulfil this gap, this work presents the results acquired from an instrumented physical model designed to study the interaction between a pipe network flow and a floodplain flow. The full range of sewer-to-surface and surface-to-sewer flow conditions at the exchange zone are experimentally analysed in both steady and unsteady flow regimes. Steady state measured discharges are first analysed considering the relationship between the energy heads from the sewer flow and the floodplain flow; these results show that existing weir and orifice formulae are valid for describing the flow exchange for the present physical model, and yield new calibrated discharge coefficients for each of the flow conditions. The measured exchange discharges are also integrated (as a source term) within a 2D numerical flood model (a finite volume solver to the 2D Shallow Water Equations (SWE)), which is shown to reproduce the observed coefficients. This calibrated numerical model is then used to simulate a series of unsteady flow tests reproduced within the experimental facility. Results show that the numerical model overestimated the values of mean surcharge flow rate. This suggests the occurrence of additional head losses in unsteady conditions which are not currently accounted for within flood models calibrated in steady flow conditions.

  6. Experimental study of core bypass flow in a prismatic VHTR based on a two-layer block model

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huhu, E-mail: huhuwang@tamu.edu; Hassan, Yassin A., E-mail: y-hassan@tamu.edu; Dominguez-Ontiveros, Elvis, E-mail: elvisdom@tamu.edu

    2016-09-15

    Bypass flow in a prismatic very high temperature gas-cooled nuclear reactor (VHTR) plays an important role in determining the coolant distribution in the core region. Efficient removal of heat from the core relies on the majority of coolant passing through the coolant channels instead of the bypass gaps. Consequently, the bypass flow fraction and its flow characteristic are important in the design process of the prismatic VHTR. The objective of this study is to experimentally investigate the flow behavior including the turbulence characteristics inside the bypass gaps using laser Doppler velocimetry (LDV), bypass fraction and pressure drops in the system. The experiment facility constructed at Texas A&M University is a scaled model consisting of two layers of fuel blocks. The distributions of the mean streamwise velocity, turbulence intensity and turbulence kinetic energy within the bypass gap at two different elevations under different Reynolds number were investigated. Uncertainties in the bypass flow fraction estimation were evaluated. The velocity and turbulence study in this work is considered to be unique, and may serve as a benchmark for the related numerical calculations.

  7. Flow and heat transfer thermohydraulic modelisation during the reflooding phase of a P.W.R.'s core

    International Nuclear Information System (INIS)

    Raymond, Patrick

    1978-04-01

    Some generalities about L.O.C.A. are first recalled. The French experimental studies about Emergency Core Cooling System are briefly described. The different heat transfer mechanisms to take into account, according to the flow pattern in the dry zone, and the correlations or methods to calculate them, are defined. Then the Thermohydraulic code computer: FLIRA, which describe the reflooding phase, and a modelisation taking into account the different flow patterns are setted. A first interpretation of ERSEC experiments with a tubular test section shows that it is possible, with this modelisation and some classical heat transfer correlations, to describe the reflooding phase. [fr

  8. Core2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    International Nuclear Information System (INIS)

    Samper, J.; Juncosa, R.; Delgado, J.; Montenegro, L.

    2000-01-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  9. Core 2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    Energy Technology Data Exchange (ETDEWEB)

    Samper, J; Juncosa, R; Delgado, J; Montenegro, L [Universidad de A Coruna (Spain)

    2000-07-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  10. Core 2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    Energy Technology Data Exchange (ETDEWEB)

    Samper, J.; Juncosa, R.; Delgado, J.; Montenegro, L. [Universidad de A Coruna (Spain)

    2000-07-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  11. THE CASE AGAINST WARM OR SELF-INTERACTING DARK MATTER AS EXPLANATIONS FOR CORES IN LOW SURFACE BRIGHTNESS GALAXIES

    International Nuclear Information System (INIS)

    Kuzio de Naray, Rachel; Martinez, Gregory D.; Bullock, James S.; Kaplinghat, Manoj

    2010-01-01

    Warm dark matter (WDM) and self-interacting dark matter (SIDM) are often motivated by the inferred cores in the dark matter halos of low surface brightness (LSB) galaxies. We test thermal WDM, non-thermal WDM, and SIDM using high-resolution rotation curves of nine LSB galaxies. We fit these dark matter models to the data and determine the halo core radii and central densities. While the minimum core size in WDM models is predicted to decrease with halo mass, we find that the inferred core radii increase with halo mass and also cannot be explained with a single value of the primordial phase-space density. Moreover, if the core size is set by WDM particle properties, then even the smallest cores we infer would require primordial phase-space density values that are orders of magnitude smaller than lower limits obtained from the Lyα forest power spectra. We also find that the dark matter halo core densities vary by a factor of about 30 from system to system while showing no systematic trend with the maximum rotation velocity of the galaxy. This strongly argues against the core size being directly set by large self-interactions (scattering or annihilation) of dark matter. We therefore conclude that the inferred cores do not provide motivation to prefer WDM or SIDM over other dark matter models.

  12. Determination of averaged axisymmetric flow surfaces according to results obtained by numerical simulation of flow in turbomachinery

    Directory of Open Access Journals (Sweden)

    Bogdanović-Jovanović Jasmina B.

    2012-01-01

    Full Text Available In the increasing need for energy saving worldwide, the designing process of turbomachinery, as an essential part of thermal and hydroenergy systems, goes in the direction of enlarging efficiency. Therefore, the optimization of turbomachinery designing strongly affects the energy efficiency of the entire system. In the designing process of turbomachinery blade profiling, the model of axisymmetric fluid flows is commonly used in technical practice, even though this model suits only the profile cascades with infinite number of infinitely thin blades. The actual flow in turbomachinery profile cascades is not axisymmetric, and it can be fictively derived into the axisymmetric flow by averaging flow parameters in the blade passages according to the circular coordinate. Using numerical simulations of flow in turbomachinery runners, its operating parameters can be preliminarily determined. Furthermore, using the numerically obtained flow parameters in the blade passages, averaged axisymmetric flow surfaces in blade profile cascades can also be determined. The method of determination of averaged flow parameters and averaged meridian streamlines is presented in this paper, using the integral continuity equation for averaged flow parameters. With thus obtained results, every designer can be able to compare the obtained averaged flow surfaces with axisymmetric flow surfaces, as well as the specific work of elementary stages, which are used in the procedure of blade designing. Numerical simulations of flow in an exemplary axial flow pump, used as a part of the thermal power plant cooling system, were performed using Ansys CFX. [Projekat Ministarstva nauke Republike Srbije, br. TR33040: Revitalization of existing and designing new micro and mini hydropower plants (from 100 kW to 1000 kW in the territory of South and Southeast Serbia

  13. Steady-state thermal hydraulic analysis and flow channel blockage accident analysis of JRR-3 silicide core

    International Nuclear Information System (INIS)

    Kaminaga, Masanori

    1997-03-01

    JRR-3 is a light water moderated and cooled, beryllium and heavy water reflected pool type research reactor using low enriched uranium (LEU) plate-type fuels. Its thermal power is 20 MW. The core conversion program from uranium-aluminum (UAl x -Al) dispersion type fuel (aluminide fuel) to uranium-silicon-aluminum (U 3 Si 2 -Al) dispersion type fuel (silicide fuel) is currently conducted at the JRR-3. This report describes about the steady-state thermal hydraulic analysis results and the flow channel blockage accident analysis result. In JRR-3, there are two operation mode. One is high power operation mode up to 20 MW, under forced convection cooling using the primary and the secondary cooling systems. The other is low power operation mode up to 200 kW, under natural circulation cooling between the reactor core and the reactor pool without the primary and the secondary cooling systems. For the analysis of the flow channel blockage accident, COOLOD code was used. On the other hand, steady-state thermal hydraulic analysis for both of the high power operation mode under forced convection cooling and low power operation under natural convection cooling, COOLOD-N2 code was used. From steady-state thermal hydraulic analysis results of both forced and natural convection cooling, fuel temperature, minimum DNBR etc. meet the design criteria and JRR-3 LEU silicide core has enough safety margin under normal operation conditions. Furthermore, flow channel blockage accident analysis results show that one channel flow blockage accident meet the safety criteria for accident conditions which have been established for JRR-3 LEU silicide core. (author)

  14. Core barrel inner tube lifter

    Energy Technology Data Exchange (ETDEWEB)

    Jeffers, J P

    1968-07-16

    A core drill with means for selectively lifting a core barrel inner tube consists of a lifting means connected to the core barrel inner tube assembly. It has a closable passage to permit drilling fluid normally to pass through it. The lifting means has a normally downward facing surface and a means to direct drilling fluid pressure against that surface so that on closure of the passage to fluid flow, the pressure of the drilling fluid is caused to act selectively on it. This causes the lifting means to rise and lift the core barrel. (7 claims)

  15. Upper Meter Processes: Short Wind Waves, Surface Flow, and Micro-Turbulence

    National Research Council Canada - National Science Library

    Jaehne, Bernd

    2000-01-01

    The primary goal of this project was to advance the knowledge of small-scale air-sea interaction processes at the ocean surface, focussing on the dynamics of short waves, the surface flow field and the micro-turbulence...

  16. Modeling Surface Water Flow in the Atchafalaya Basin

    Science.gov (United States)

    Liu, K.; Simard, M.

    2017-12-01

    While most of the Mississippi River Delta is sinking due to insufficient sediment supply and subsidence, the stable wetlands and the prograding delta systems in the Atchafalaya Basin provide a unique opportunity to study the constructive interactions between riverine and marine forcings and their impacts upon coastal morphology. To better understand the hydrodynamics in this region, we developed a numerical modeling system for the water flow through the river channel - deltas - wetlands networks in the Atchafalaya Basin. Determining spatially varying model parameters for a large area composed of such diverse land cover types poses a challenge to developing an accurate numerical model. For example, the bottom friction coefficient can not be measured directly and the available elevation maps for the wetlands in the basin are inaccurate. To overcome these obstacles, we developed the modeling system in three steps. Firstly, we modeled river bathymetry based on in situ sonar transects and developed a simplified 1D model for the Wax Lake Outlet using HEC-RAS. Secondly, we used a Bayesian approach to calibrate the model automatically and infer important unknown parameters such as riverbank elevation and bottom friction coefficient through Markov Chain Monte Carlo (MCMC) simulations. We also estimated the wetland elevation based on the distribution of different vegetation species in the basin. Thirdly, with the lessons learnt from the 1D model, we developed a depth-averaged 2D model for the whole Atchafalaya Basin using Delft3D. After calibrations, the model successfully reproduced the water levels measured at five gauges in the Wax Lake Outlet and the modeled water surface profile along the channel agreed reasonably well with our LIDAR measurements. In addition, the model predicted a one-hour delay in tidal phase from the Wax Lake Delta to the upstream gauge. In summary, this project presents a procedure to initialize hydrology model parameters that integrates field

  17. Development of an optimization technique of CETOP-D inlet flow factor for reactor core thermal margin improvement

    International Nuclear Information System (INIS)

    Hong, Sung Duk; Im, Jong Sun; Yoo, Yun Jong; Kwon, Jung Taek; Park, Jong Ryool

    1995-01-01

    The recent ABB/CE(Asea Brown Boveri Combustion Engineering) type pressurized water reactors have the on-line monitoring system, i.e., the COLSS(core operating limit supervisory system), to prevent the specified acceptable fuel design limits from being violated during normal operation and anticipated operational occurrences. One of the main functions of COLSS is the on-line monitoring of the DNB(departure from nucleate boiling) overpower margin by calculating the MDNBR(minimum DNB ratio) for the measured operating condition at every second. The CETOP-D model, used in the MDNBR calculation of COLSS, is benchmarked conservatively against the TORC model using an inlet flow factor of hot assembly in CETOP-D as an adjustment factor for TORC. In this study, a technique to optimize the CETOP-D inlet flow factor has been developed by eliminating the excessive conservatism in the ABB/CE's. A correlation is introduced to account for the actual variation of the CETOP-D inlet flow factor within the core operating limits. This technique was applied to the core operating range of the Yonggwang Units 3 and 4 Cycle 1, which results in the increase of 2% in the DNB overpower margin at the normal operating condition, compared with that from the ABB/CE method. 7 figs., 2 tabs., 10 refs. (Author)

  18. 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)

  19. Nuclear core baffling apparatus

    International Nuclear Information System (INIS)

    Cooper, F.W. Jr.; Silverblatt, B.L.; Knight, C.B.; Berringer, R.T.

    1979-01-01

    An apparatus for baffling the flow of reactor coolant fluid into and about the core of a nuclear reactor is described. The apparatus includes a plurality of longitudinally aligned baffle plates with mating surfaces that allow longitudinal growth with temperature increases while alleviating both leakage through the aligned plates and stresses on the components supporting the plates

  20. Enteric and indicator virus removal by surface flow wetlands.

    Science.gov (United States)

    Rachmadi, Andri T; Kitajima, Masaaki; Pepper, Ian L; Gerba, Charles P

    2016-01-15

    We investigated the occurrence and attenuation of several human enteric viruses (i.e., norovirus, adenovirus, Aichi virus 1, polyomaviruses, and enterovirus) as well as a plant virus, pepper mild mottle virus (PMMoV), at two surface flow wetlands in Arizona. The retention time in one of the wetlands was seven days, whereas in the other wetland it could not be defined. Water samples were collected at the inlet and outlet from the wetlands over nine months, and concentration of viral genomes was determined by quantitative polymerase chain reaction (qPCR). Of the human enteric viruses tested, adenovirus and Aichi virus 1 were found in the greatest prevalence in treated wastewater (i.e., inlet of the wetlands). Reduction efficiencies of enteric viruses by the wetlands ranged from 1 to 3 log10. Polyomaviruses were generally removed to below detection limit, indicating at least 2 to 4 log10 removal. PMMoV was detected in a greater concentration in the inlet of both wetlands for all the viruses tested (10(4) to 10(7) genome copies/L), but exhibited little or no removal (1 log10 or less). To determine the factors associated with virus genome attenuation (as determined by qPCR), the persistence of PMMoV and poliovirus type 1 (an enterovirus) was studied in autoclaved and natural wetland water, and deionized water incubated under three different temperatures for 21 days. A combination of elevated water temperature and biological activities reduced poliovirus by 1 to 4 log10, while PMMoV was not significantly reduced during this time period. Overall, PMMoV showed much greater persistence than human viruses in the wetland treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Robust Detection and Visualization of Jet-Stream Core Lines in Atmospheric Flow.

    Science.gov (United States)

    Kern, Michael; Hewson, Tim; Sadlo, Filip; Westermann, Rudiger; Rautenhaus, Marc

    2018-01-01

    Jet-streams, their core lines and their role in atmospheric dynamics have been subject to considerable meteorological research since the first half of the twentieth century. Yet, until today no consistent automated feature detection approach has been proposed to identify jet-stream core lines from 3D wind fields. Such 3D core lines can facilitate meteorological analyses previously not possible. Although jet-stream cores can be manually analyzed by meteorologists in 2D as height ridges in the wind speed field, to the best of our knowledge no automated ridge detection approach has been applied to jet-stream core detection. In this work, we -a team of visualization scientists and meteorologists-propose a method that exploits directional information in the wind field to extract core lines in a robust and numerically less involved manner than traditional 3D ridge detection. For the first time, we apply the extracted 3D core lines to meteorological analysis, considering real-world case studies and demonstrating our method's benefits for weather forecasting and meteorological research.

  2. Magnetized Converging Flows toward the Hot Core in the Intermediate/High-mass Star-forming Region NGC 6334 V

    Energy Technology Data Exchange (ETDEWEB)

    Juárez, Carmen; Girart, Josep M. [Institut de Ciències de l’Espai, (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, S/N, E-08193 Cerdanyola del Vallès, Catalonia (Spain); Zamora-Avilés, Manuel; Palau, Aina; Ballesteros-Paredes, Javier [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090, Morelia, Michoacán (Mexico); Tang, Ya-Wen; Koch, Patrick M.; Liu, Hauyu Baobab [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 10617, Taiwan (China); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Qiu, Keping, E-mail: juarez@ice.cat [School of Astronomy and Space Science, Nanjing University, 163 Xianlin Avenue, Nanjing 210023 (China)

    2017-07-20

    We present Submillimeter Array (SMA) observations at 345 GHz toward the intermediate/high-mass cluster-forming region NGC 6334 V. From the dust emission we spatially resolve three dense condensations, the brightest one presenting the typical chemistry of a hot core. The magnetic field (derived from the dust polarized emission) shows a bimodal converging pattern toward the hot core. The molecular emission traces two filamentary structures at two different velocities, separated by 2 km s{sup −1}, converging to the hot core and following the magnetic field distribution. We compare the velocity field and the magnetic field derived from the SMA observations with magnetohydrodynamic simulations of star-forming regions dominated by gravity. This comparison allows us to show how the gas falls in from the larger-scale extended dense core (∼0.1 pc) of NGC 6334 V toward the higher-density hot core region (∼0.02 pc) through two distinctive converging flows dragging the magnetic field, whose strength seems to have been overcome by gravity.

  3. Magnetized Converging Flows toward the Hot Core in the Intermediate/High-mass Star-forming Region NGC 6334 V

    International Nuclear Information System (INIS)

    Juárez, Carmen; Girart, Josep M.; Zamora-Avilés, Manuel; Palau, Aina; Ballesteros-Paredes, Javier; Tang, Ya-Wen; Koch, Patrick M.; Liu, Hauyu Baobab; Zhang, Qizhou; Qiu, Keping

    2017-01-01

    We present Submillimeter Array (SMA) observations at 345 GHz toward the intermediate/high-mass cluster-forming region NGC 6334 V. From the dust emission we spatially resolve three dense condensations, the brightest one presenting the typical chemistry of a hot core. The magnetic field (derived from the dust polarized emission) shows a bimodal converging pattern toward the hot core. The molecular emission traces two filamentary structures at two different velocities, separated by 2 km s −1 , converging to the hot core and following the magnetic field distribution. We compare the velocity field and the magnetic field derived from the SMA observations with magnetohydrodynamic simulations of star-forming regions dominated by gravity. This comparison allows us to show how the gas falls in from the larger-scale extended dense core (∼0.1 pc) of NGC 6334 V toward the higher-density hot core region (∼0.02 pc) through two distinctive converging flows dragging the magnetic field, whose strength seems to have been overcome by gravity.

  4. Surface characterization of hydrophobic core-shell QDs using NMR techniques

    Science.gov (United States)

    Zhang, Chengqi; Zeng, Birong; Palui, Goutam; Mattoussi, Hedi

    2018-02-01

    Using a few solution phase NMR spectroscopy techniques, including 1H NMR and 31P NMR, we have characterized the organic shell on CdSe-ZnS core-shell quantum dots and tracked changes in its composition when the QD dispersions are subjected to varying degrees of purification. Combining solution phase NMR with diffusion ordered spectroscopy (DOSY), we were able to distinguish between freely diffusing ligands in the sample from those bound on the surfaces. Additionally, matrix assisted laser desorption ionization (MALDI) and FTIR measurements were used to provide complementary and supporting information on the organic ligand coating for these nanocrystals. We found that the organic shell is dominated by monomeric or oligomeric n-hexylphosphonic acid (HPA), along with small portion of 1-hexadecyl amine (HDA). The presence of TOP/TOPO (tri-n-octylphosphine / tri-noctylphosphine oxide) molecules is much smaller, even though large excess of TOP/TOPO were used during the QD growth. These results indicate that HPA (alkyl phosphonate) exhibits the strongest coordination affinity to ZnS-rich QD surfaces grown using the high temperature injection route.

  5. Characteristics of Nitrogen Loss through Surface-Subsurface Flow on Red Soil Slopes of Southeast China

    Science.gov (United States)

    Zheng, Haijin; Liu, Zhao; Zuo, Jichao; Wang, Lingyun; Nie, Xiaofei

    2017-12-01

    Soil nitrogen (N) loss related to surface flow and subsurface flow (including interflow and groundwater flow) from slope lands is a global issue. A lysimetric experiment with three types of land cover (grass cover, GC; litter cover, LC; and bare land, BL) were carried out on a red soil slope land in southeast China. Total Nitrogen (TN) loss through surface flow, interflow and groundwater flow was observed under 28 natural precipitation events from 2015 to 2016. TN concentrations from subsurface flow on BL and LC plots were, on average, 2.7-8.2 and 1.5-4.4 times greater than TN concentrations from surface flow, respectively; the average concentration of TN from subsurface flow on GC was about 36-56% of that recorded from surface flow. Surface flow, interflow and groundwater flow contributed 0-15, 2-9 and 76-96%, respectively, of loss load of TN. Compared with BL, GC and LC intercepted 83-86% of TN loss through surface runoff; GC intercepted 95% of TN loss through subsurface flow while TN loss through subsurface flow on LC is 2.3 times larger than that on BL. In conclusion, subsurface flow especially groundwater flow is the dominant hydrological rout for N loss that is usually underestimated. Grass cover has the high retention of N runoff loss while litter mulch will increase N leaching loss. These findings provide scientific support to control N runoff loss from the red soil slope lands by using suitable vegetation cover and mulching techniques.

  6. Retention mechanisms and the flow wetted surface - implications for safety analysis

    International Nuclear Information System (INIS)

    Elert, M.

    1997-02-01

    The purpose of this report is to document the state-of-the-art concerning the flow wetted surface, its importance for radionuclide transport in the geosphere and review various suggestions on how to increase the present knowledge. Definitions are made of the various concepts used for the flow wetted surface as well as the various model parameters used. In the report methods proposed to assess the flow wetted surface are reviewed and discussed, tracer tests, tunnel and borehole investigations, geochemical studies, heat transport studies and theoretical modelling. Furthermore, a review is made of how the flow wetted surface has been treated in various safety analyses. Finally, an overall discussion with recommendations is presented, where it is concluded that at present no individual method for estimating the flow wetted surface can be selected that satisfies all requirements concerning giving relevant values, covering relevant distances and being practical to apply. Instead a combination of methods must be used. In the long-term research as well as in the safety assessment modelling focus should be put on assessing the ratio between flow wetted surface and water flux. The long-term research should address both the detailed flow within the fractures and the effective flow wetted surface along the flow paths. 55 refs

  7. Development of the loss coefficient correlation for cross flow between graphite fuel blocks in the core of prismatic very high temperature reactor-PMR200

    International Nuclear Information System (INIS)

    Lee, Jeong-Hun; Cho, Hyoung-Kyu; Park, Goon-Cherl

    2016-01-01

    Highlights: • Cross flow experimental data are produced with wedge-shaped and parallel gaps. • The results of a CFD analysis and experimental data are in good agreement. • Pressure loss coefficient for the cross gap between fuel blocks in PMR200 is found. • A new correlation of the cross flow loss coefficient for PMR200 is proposed. - Abstract: The core of the very high temperature reactor (VHTR) PMR200 (a prismatic modular reactor rated at 200 MW of thermal power) consists of hexagonal prismatic fuel blocks and reflector blocks made of graphite. If the core bypass flow ratio increases, the coolant channel flow is decreased and can then lower the heat removal efficiency, resulting in a locally increased fuel block temperature. The coolant channels in the fuel blocks are connected to bypass gaps by the cross gap, complicating flow distribution in the VHTR core. Therefore, reliable estimation of the bypass flow is highly important for the design and safety analysis of the VHTR core. Because of the complexity of the core geometry and gap configuration, it is challenging to predict the flow distribution in the VHTR core. To analyze this flow distribution accurately, it is necessary to determine the cross flow phenomena, and the loss coefficient across the cross gap has to be evaluated to determine the flow distribution in the VHTR core when a lumped parameter code or a flow network analysis code that uses the correlation of the loss coefficient is employed. The purpose of this paper is to develop a loss coefficient correlation applicable to the cross gap in the PMR200 core. The cross flow was evaluated experimentally using the difference between the measured inlet and outlet mass flow rates. Next, the applicability of a commercial computational fluid dynamics (CFD) code, CFX 15, was confirmed by comparing the experimental data and CFD analysis results. To understand the cross flow phenomena, the loss coefficient was evaluated; in the high Reynolds number region

  8. Development of the loss coefficient correlation for cross flow between graphite fuel blocks in the core of prismatic very high temperature reactor-PMR200

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong-Hun, E-mail: huny12@snu.ac.kr; Cho, Hyoung-Kyu, E-mail: chohk@snu.ac.kr; Park, Goon-Cherl, E-mail: parkgc@snu.ac.kr

    2016-10-15

    Highlights: • Cross flow experimental data are produced with wedge-shaped and parallel gaps. • The results of a CFD analysis and experimental data are in good agreement. • Pressure loss coefficient for the cross gap between fuel blocks in PMR200 is found. • A new correlation of the cross flow loss coefficient for PMR200 is proposed. - Abstract: The core of the very high temperature reactor (VHTR) PMR200 (a prismatic modular reactor rated at 200 MW of thermal power) consists of hexagonal prismatic fuel blocks and reflector blocks made of graphite. If the core bypass flow ratio increases, the coolant channel flow is decreased and can then lower the heat removal efficiency, resulting in a locally increased fuel block temperature. The coolant channels in the fuel blocks are connected to bypass gaps by the cross gap, complicating flow distribution in the VHTR core. Therefore, reliable estimation of the bypass flow is highly important for the design and safety analysis of the VHTR core. Because of the complexity of the core geometry and gap configuration, it is challenging to predict the flow distribution in the VHTR core. To analyze this flow distribution accurately, it is necessary to determine the cross flow phenomena, and the loss coefficient across the cross gap has to be evaluated to determine the flow distribution in the VHTR core when a lumped parameter code or a flow network analysis code that uses the correlation of the loss coefficient is employed. The purpose of this paper is to develop a loss coefficient correlation applicable to the cross gap in the PMR200 core. The cross flow was evaluated experimentally using the difference between the measured inlet and outlet mass flow rates. Next, the applicability of a commercial computational fluid dynamics (CFD) code, CFX 15, was confirmed by comparing the experimental data and CFD analysis results. To understand the cross flow phenomena, the loss coefficient was evaluated; in the high Reynolds number region

  9. Free surface flow of a suspension of rigid particles in a non-Newtonian fluid

    DEFF Research Database (Denmark)

    Svec, Oldrich; Skocek, Jan; Stang, Henrik

    2012-01-01

    A numerical framework capable of predicting the free surface flow of a suspension of rigid particles in a non-Newtonian fluid is described. The framework is a combination of the lattice Boltzmann method for fluid flow, the mass tracking algorithm for free surface representation, the immersed...

  10. Turbulent oscillating channel flow subjected to a free-surface stress.

    NARCIS (Netherlands)

    Kramer, W.; Clercx, H.J.H.; Armenio, V.

    2010-01-01

    The channel flow subjected to a wind stress at the free surface and an oscillating pressure gradient is investigated using large-eddy simulations. The orientation of the surface stress is parallel with the oscillating pressure gradient and a purely pulsating mean flow develops. The Reynolds number

  11. Convective heat transfer from rough surfaces with two-dimensional ribs - transitional and laminar flow

    International Nuclear Information System (INIS)

    Dalle Donne, M.; Meyer, L.

    1978-01-01

    Measurements of friction factor and heat transfer coefficients for two rods of 18.9 mm 0.D. with two-dimensional roughness, each in two different outer smooth tubes have been performed in turbulent and laminar flow. The turbulent flow results indicate that the flow was not thermally fully established, the isothermal data however agree reasonably well with our previously obtained general correlation. Laminar flow results can be correlated best when the Reynolds and Greatz numbers are evaluated at the temperature average between the temperature of the inner rod surface and of the outer smooth surface of the annulus, the average being weighted over the two surfaces. (orig.) [de

  12. Radioimmunoassay of surface antigen and core antibody of hepatitis B virus. Comparison of kits AUSRIA/CORE; AUSRIA II-125 and CORAB

    Energy Technology Data Exchange (ETDEWEB)

    Kselikova, M; Urbankova, J [Ustav Hematologie a Krevni Transfuze, Prague (Czechoslovakia)

    1984-08-01

    The sensitivity is compared of determination of surface antigen HBsAg and nuclear antibody HBcAb of the hepatitis B virus using kits for separate (AUSRIA II-125, CORAB) and simultaneous (AUSRIAsup(R)/CORE) determinations of third generation tests in selected samples of medical personnel, HBsAg carriers, patients at a dialysis centre, blood donors and in sera of HBsAg carriers diluted in steps from 4x10/sup -2/ to 4x10/sup -7/. HBsAg is always determined using the RIA technique, HBcAb is determined using the technique of radioimmunoassay with the CORAB kit and with the AUSRIA sup(R)/CORE kit using enzymeimmunoassay. The sensitivity of determination using the AUSRIA sup(R)/CORE kit is at least as good for both investigated indicators of the hepatitis B virus and that obtained using separate determination of HBsAg (AUSRIA II-125) and HBcAb (CORAB), this also using modified photocolorimetric determination. Only one AUSRIA/sup R//CORE kit was available for the investigation and the informative character of the report is emphasized.

  13. Measurement of the interaction between the flow and the free surface of a liquid

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Koji [Univ. of Tokyo, Ibaraki (Japan); Schmidl, W.D.; Philip, O.G. [Texas A& M Univ., College Station, TX (United States)

    1995-09-01

    The interaction between the flow and free surface was evaluated measuring the velocity distribution and surface movement simultaneously. The test section was a rectangular tank having a free surface. A rectangular nozzle was set near the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The higher fluctuation of horizontal velocity was related to the higher surface position and negative inclination. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow.

  14. Measurement of the interaction between the flow and the free surface of a liquid

    International Nuclear Information System (INIS)

    Okamoto, Koji; Schmidl, W.D.; Philip, O.G.

    1995-01-01

    The interaction between the flow and free surface was evaluated measuring the velocity distribution and surface movement simultaneously. The test section was a rectangular tank having a free surface. A rectangular nozzle was set near the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The higher fluctuation of horizontal velocity was related to the higher surface position and negative inclination. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow

  15. Large-Scale Flows and Magnetic Fields Produced by Rotating Convection in a Quasi-Geostrophic Model of Planetary Cores

    Science.gov (United States)

    Guervilly, C.; Cardin, P.

    2017-12-01

    Convection is the main heat transport process in the liquid cores of planets. The convective flows are thought to be turbulent and constrained by rotation (corresponding to high Reynolds numbers Re and low Rossby numbers Ro). Under these conditions, and in the absence of magnetic fields, the convective flows can produce coherent Reynolds stresses that drive persistent large-scale zonal flows. The formation of large-scale flows has crucial implications for the thermal evolution of planets and the generation of large-scale magnetic fields. In this work, we explore this problem with numerical simulations using a quasi-geostrophic approximation to model convective and zonal flows at Re 104 and Ro 10-4 for Prandtl numbers relevant for liquid metals (Pr 0.1). The formation of intense multiple zonal jets strongly affects the convective heat transport, leading to the formation of a mean temperature staircase. We also study the generation of magnetic fields by the quasi-geostrophic flows at low magnetic Prandtl numbers.

  16. Self-induced oscillation of free surface in a tank with circulating flow, 2

    International Nuclear Information System (INIS)

    Okamoto, Koji; Madarame, Haruki; Hagiwara, Tsuyoshi

    1991-01-01

    An energy supply mechanism to self-induced sloshing in a tank with circulating flow is proposed. The circulating flow impinges on the free surface making it swell partially. The amount of swell increases with increasing water level under the condition of growing sloshing. The change of the free surface contour by this effect supplies sufficient energy to the sloshing. The dependency of the sloshing growth on the flow rate and the water level is explained well by this model. (author)

  17. Breccia-cored columnar rosettes in a rubbly pahoehoe lava flow, Elephanta Island, Deccan Traps, and a model for their origin

    Directory of Open Access Journals (Sweden)

    Hetu Sheth

    2017-11-01

    Full Text Available Rubbly pahoehoe lava flows are abundant in many continental flood basalts including the Deccan Traps. However, structures with radial joint columns surrounding cores of flow-top breccia (FTB, reported from some Deccan rubbly pahoehoe flows, are yet unknown from other basaltic provinces. A previous study of these Deccan “breccia-cored columnar rosettes” ruled out explanations such as volcanic vents and lava tubes, and showed that the radial joint columns had grown outwards from cold FTB inclusions incorporated into the hot molten interiors. How the highly vesicular (thus low-density FTB blocks might have sunk into the flow interiors has remained a puzzle. Here we describe a new example of a Deccan rubbly pahoehoe flow with FTB-cored rosettes, from Elephanta Island in the Mumbai harbor. Noting that (1 thick rubbly pahoehoe flows probably form by rapid inflation (involving many lava injections into a largely molten advancing flow, and (2 such flows are transitional to ‘a’ā flows (which continuously shed their top clinker in front of them as they advance, we propose a model for the FTB-cored rosettes. We suggest that the Deccan flows under study were shedding some of their FTB in front of them as they advanced and, with high-eruption rate lava injection and inflation, frontal breakouts would incorporate this FTB rubble, with thickening of the flow carrying the rubble into the flow interior. This implies that, far from sinking into the molten interior, the FTB blocks may have been rising, until lava supply and inflation stopped, the flow began solidifying, and joint columns developed outward from each cold FTB inclusion as already inferred, forming the FTB-cored rosettes. Those rubbly pahoehoe flows which began recycling most of their FTB became the ‘a’ā flows of the Deccan.

  18. Heat transfer and forces on concave surfaces in free molecule flow.

    Science.gov (United States)

    Fan, C.

    1971-01-01

    A Monte Carlo modeling technique is described for mathematically simulating free molecular flows over a concave spherical surface and a concave cylindrical surface of finite length. The half-angle of the surfaces may vary from 0 to 90 degrees, and the incident flow may have an arbitrary speed ratio and an arbitrary angle of attack. Partial diffuse reflection and imperfect energy accommodation for molecules colliding with the surfaces are also considered. Results of heat transfer, drag and lift coefficients are presented for a variety of flow conditions. The present Monte Carlo results are shown to be in very good agreement with certain available theoretical solutions.

  19. A method and programme (BREACH) for predicting the flow distribution in water cooled reactor cores

    International Nuclear Information System (INIS)

    Randles, J.; Roberts, H.A.

    1961-03-01

    The method presented here of evaluating the flow rate in individual reactor channels may be applied to any type of water cooled reactor in which boiling occurs The flow distribution is calculated with the aid of a MERCURY autocode programme, BREACH, which is described in detail. This programme computes the steady state longitudinal void distribution and pressure drop in a single channel on the basis of the homogeneous model of two phase flow. (author)

  20. A method and programme (BREACH) for predicting the flow distribution in water cooled reactor cores

    Energy Technology Data Exchange (ETDEWEB)

    Randles, J; Roberts, H A [Technical Assessments and Services Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1961-03-15

    The method presented here of evaluating the flow rate in individual reactor channels may be applied to any type of water cooled reactor in which boiling occurs The flow distribution is calculated with the aid of a MERCURY autocode programme, BREACH, which is described in detail. This programme computes the steady state longitudinal void distribution and pressure drop in a single channel on the basis of the homogeneous model of two phase flow. (author)

  1. In Vitro Evaluation of Various Surface Treatments of Fiber Posts on the Bond Strength to Composite Core

    Directory of Open Access Journals (Sweden)

    Sareh Nadalizadeh

    Full Text Available Introduction: The reliable bond at the root-post-core interface is critical for the clinical success of post-retained restorations. To decrease the risk of fracture, it is important to optimize the adhesion. Therefore, various post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of fiber posts on the bond strength to composite core. Materials & Methods: In this study, 40 fiber reinforced posts were used. After preparing and sectioning them, resulting specimens were divided into four groups (N=28. The posts received different surface treatments such as no surface treatment (control group, preparing with hydrogen peroxide 10%, preparing with silane, preparing with HF and silane. Then, posts were tested in micro tensile testing machine. The results were analyzed by One-Way ANOVA and Dunnett T3 test. Results: The greatest bond strength observed was in treatment with hydrogen peroxide 10% (19.84±8.95 MPa, and the lowest strength was related to the control group (12.44±3.40 MPa. The comparison of the groups with Dunnett T3 test showed that the differences between the groups was statistically significant (α=0.05.Conclusion: Based on the results of this study, preparing with H2O2 -10 % and silane increases the bond strength of FRC posts to the composite core more than the other methods. Generally, the bond strength of posts to the composite core increases by surface treatment.

  2. Method of driving liquid flow at or near the free surface using magnetic microparticles

    Science.gov (United States)

    Snezhko, Oleksiy [Woodridge, IL; Aronson, Igor [Darien, IL; Kwok, Wai-Kwong [Evanston, IL; Belkin, Maxim V [Woodridge, IL

    2011-10-11

    The present invention provides a method of driving liquid flow at or near a free surface using self-assembled structures composed of magnetic particles subjected to an external AC magnetic field. A plurality of magnetic particles are supported at or near a free surface of liquid by surface tension or buoyancy force. An AC magnetic field traverses the free surface and dipole-dipole interaction between particles produces in self-assembled snake structures which oscillate at the frequency of the traverse AC magnetic field. The snake structures independently move across the free surface and may merge with other snake structures or break up and coalesce into additional snake structures experiencing independent movement across the liquid surface. During this process, the snake structures produce asymmetric flow vortices across substantially the entirety of the free surface, effectuating liquid flow across the free surface.

  3. Experimental and numerical investigations of high temperature gas heat transfer and flow in a VHTR reactor core

    Science.gov (United States)

    Valentin Rodriguez, Francisco Ivan

    High pressure/high temperature forced and natural convection experiments have been conducted in support of the development of a Very High Temperature Reactor (VHTR) with a prismatic core. VHTRs are designed with the capability to withstand accidents by preventing nuclear fuel meltdown, using passive safety mechanisms; a product of advanced reactor designs including the implementation of inert gases like helium as coolants. The present experiments utilize a high temperature/high pressure gas flow test facility constructed for forced and natural circulation experiments. This work examines fundamental aspects of high temperature gas heat transfer applied to VHTR operational and accident scenarios. Two different types of experiments, forced convection and natural circulation, were conducted under high pressure and high temperature conditions using three different gases: air, nitrogen and helium. The experimental data were analyzed to obtain heat transfer coefficient data in the form of Nusselt numbers as a function of Reynolds, Grashof and Prandtl numbers. This work also examines the flow laminarization phenomenon (turbulent flows displaying much lower heat transfer parameters than expected due to intense heating conditions) in detail for a full range of Reynolds numbers including: laminar, transition and turbulent flows under forced convection and its impact on heat transfer. This phenomenon could give rise to deterioration in convection heat transfer and occurrence of hot spots in the reactor core. Forced and mixed convection data analyzed indicated the occurrence of flow laminarization phenomenon due to the buoyancy and acceleration effects induced by strong heating. Turbulence parameters were also measured using a hot wire anemometer in forced convection experiments to confirm the existence of the flow laminarization phenomenon. In particular, these results demonstrated the influence of pressure on delayed transition between laminar and turbulent flow. The heat

  4. Flow control inside a molten Zn pot for improving surface quality of zinc plated strips

    Energy Technology Data Exchange (ETDEWEB)

    Choi, J.H. [Samsung Techwin Co., Ltd. (Korea); Koh, M.S.; Kim, S. [Pohang University of Science and Technology Graduate School, Pohang (Korea)

    2001-10-01

    The flow fields inside a molten Zn pot of continuous hot-chip galvanizing process were investigated experimentally. With varying several parameters including the strip speed V{sub s}, flow rate Q of induction heater, scrapper location and baffle configuration, instantaneous velocity fields were measured using a PIV velocity field measurement technique. Inside the strip region, counter-clockwise rotating flow is dominant. The general flow pattern inside the strip region is nearly not influenced by the trip speed V{sub 2}, flow rate Q and the scrapper location. In the exit region, the flow separated from the moving strip due to the existence of a stabilizing roll ascends to the free surface, for the cases of no scrapper and scrapper detached form the roll. On the other hand, the ascending flow to the free surface is decreased, as the flow rate Q of induction heater increases. By installing a baffle around the uprising strip, the flow moving up to the stabilizing roll decreases. In addition, B-type baffle is better than A-type baffle in reducing speed of flow around the stabilizing rolls. However, the flow ascended to the free surface is largely influenced by changing the flow rate Q, and the scrapper location, irrespective of the baffle type. (author). 14 refs., 11 figs.

  5. Transitions to improved core electron heat confinement triggered by low order rational magnetic surfaces in the stellarator TJ-II

    International Nuclear Information System (INIS)

    Estrada, T.; Medina, F.; Lopez-Bruna, D.; AscasIbar, E.; BalbIn, R.; Cappa, A.; Castejon, F.; Eguilior, S.; Fernandez, A.; Guasp, J.; Hidalgo, C.; Petrov, S.

    2007-01-01

    Transitions to improved core electron heat confinement are triggered by low order rational magnetic surfaces in TJ-II electron cyclotron heated (ECH) plasmas. Experiments are performed changing the magnetic shear around the rational surface n = 3/m = 2 to study its influence on the transition; ECH power modulation is used to look at transport properties. The improvement in the electron heat confinement shows no obvious dependence on the magnetic shear. Transitions triggered by the rational surface n = 4/m = 2 show, in addition, an increase in the ion temperature synchronized with the increase in the electron temperature. Ion temperature changes had not been previously observed either in TJ-II or in any other helical device. SXR measurements demonstrate that, under certain circumstances, the rational surface positioned inside the plasma core region precedes and provides a trigger for the transition

  6. Turbulent-flow split model and supporting experiments for wire-wrapped core assemblies

    International Nuclear Information System (INIS)

    Chiu, C.; Todreas, N.; Rohsenow, W.

    1978-04-01

    A flow split model for the turbulent flow in a wire-wrapped nuclear fuel rod assembly is developed taking the form drag and sweeping flow between subchannels into consideration. This model is applicable to the flow distribution between two types of subchannels, i.e., interior and edge subchannels. The constants in this model for each type of subchannel were determined using all experimental data in the literature and the results of two tests performed as part of this study to fill a gap in the available literature. These experiments to measure flow split were performed on two wire-wrapped 61 pin bundles of pin pitch to pin diameter ratio, P/D, equal to 1.063 and wire lead to pin diameter ratios, H/D, of 4 and 8. The predictions of this model match all experimental data in the literature within +- 5%

  7. Self-construction of core-shell and hollow zeolite analcime icositetrahedra: a reversed crystal growth process via oriented aggregation of nanocrystallites and recrystallization from surface to core.

    Science.gov (United States)

    Chen, Xueying; Qiao, Minghua; Xie, Songhai; Fan, Kangnian; Zhou, Wuzong; He, Heyong

    2007-10-31

    Zeolite analcime with a core-shell and hollow icositetrahedron architecture was prepared by a one-pot hydrothermal route in the presence of ethylamine and Raney Ni. Detailed investigations on samples at different preparation stages revealed that the growth of the complex single crystalline geometrical structure did not follow the classic crystal growth route, i.e., a crystal with a highly symmetric morphology (such as polyhedra) is normally developed by attachment of atoms or ions to a nucleus. A reversed crystal growth process through oriented aggregation of nanocrystallites and surface recrystallization was observed. The whole process can be described by the following four successive steps. (1) Primary analcime nanoplatelets undergo oriented aggregation to yield discus-shaped particles. (2) These disci further assemble into polycrystalline microspheres. (3) The relatively large platelets grow into nanorods by consuming the smaller ones, and meanwhile, the surface of the microspheres recrystallizes into a thin single crystalline icositetrahedral shell via Ostwald ripening. (4) Recrystallization continues from the surface to the core at the expense of the nanorods, and the thickness of the monocrystalline shell keeps on increasing until all the nanorods are consumed, leading to hollow single crystalline analcime icositetrahedra. The present work adds new useful information for the understanding of the principles of zeolite growth.

  8. A high resolution photoemission study of surface core-level shifts in clean and oxygen-covered Ir(2 1 0) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gladys, M.J.; Ermanoski, I.; Jackson, G.; Quinton, J.S.; Rowe, J.E.; Madey, T.E. E-mail: madey@physics.rutgers.edu

    2004-04-01

    High resolution soft X-ray photoemission electron spectroscopy (SXPS), using synchrotron radiation, is employed to investigate 4f core-level features of four differently-prepared Ir(2 1 0) surfaces: clean planar, oxygen-covered planar, oxygen-induced faceted, and clean faceted surfaces. Surface and bulk peak identifications are supported by measurements at different photon energies (thus probing different electron escape depths) and variable emission angles. Iridium 4f{sub 7/2} photoemission spectra are fitted with Doniach-Sunjic lineshapes. The surface components are identified with core levels positioned at lower binding energies than the bulk components, in contrast to previous reports of binding energy inversion on Ir(1 0 0) (1x1) and (5x1) surfaces. For clean planar Ir(2 1 0) three surface Ir 4f{sub 7/2} features are observed with core-level shifts of -765, -529, and -281 meV, with respect to the bulk; these are associated with the first, second and third layers of atoms, respectively, for atomically rough Ir(2 1 0). Adsorption of oxygen onto the planar Ir(2 1 0) surface is found to cause a suppression and shift of the surface features to higher binding energies. Annealing at T{>=}600 K in oxygen produces a faceted surface as verified by low energy electron diffraction (LEED). A comparison of planar and faceted oxygen-covered surfaces reveals minor differences in the normal emission SXPS spectra, while grazing emission spectra exhibit differences. The SXPS spectrum of the clean, faceted Ir(2 1 0) exhibits small differences in comparison to the clean planar case, with surface features having binding energy shifts of -710, -450, and -230 meV.

  9. An Exposed-Core Grapefruit Fibers Based Surface Plasmon Resonance Sensor

    Directory of Open Access Journals (Sweden)

    Xianchao Yang

    2015-07-01

    Full Text Available To solve the problem of air hole coating and analyte filling in microstructured optical fiber-based surface plasmon resonance (SPR sensors, we designed an exposed-core grapefruit fiber (EC-GFs-based SPR sensor. The exposed section of the EC-GF is coated with a SPR, supporting thin silver film, which can sense the analyte in the external environment. The asymmetrically coated fiber can support two separate resonance peaks (x- and y-polarized peaks with orthogonal polarizations and x-polarized peak, providing a much higher peak loss than y-polarized, also the x-polarized peak has higher wavelength and amplitude sensitivities. A large analyte refractive index (RI range from 1.33 to 1.42 is calculated to investigate the sensing performance of the sensor, and an extremely high wavelength sensitivity of 13,500 nm/refractive index unit (RIU is obtained. The silver layer thickness, which may affect the sensing performance, is also discussed. This work can provide a reference for developing a high sensitivity, real-time, fast-response, and distributed SPR RI sensor.

  10. Surface states in the photoionization of high-quality CdSe core/shell nanocrystals.

    Science.gov (United States)

    Li, Shu; Steigerwald, Michael L; Brus, Louis E

    2009-05-26

    We use electric force microscopy (EFM) to study single nanocrystal photoionization in two classes of high-quality nanocrystals whose exciton luminescence quantum yields approach unity in solution. The CdSe/CdS/ZnS core/shell nanocrystals do not photoionize, while the CdSe/CdS nanocrystals do show substantial photoionization. This verifies the theoretical prediction that the ZnS shell confines the excited electron within the nanocrystal. Despite the high luminescence quantum yield, photoionization varies substantially among the CdSe/CdS nanocrystals. We have studied the nanocrystal photoionization with both UV (396 nm) and green (532 nm) light, and we have found that the magnitude of the charge due to photoionization per absorbed photon is greater for UV excitation than for green excitation. A fraction of the photoionization occurs directly via a "hot electron" process, using trap states that are either on the particle surface, within the ligand sphere, or within the silicon oxide layer. This must occur without relaxation to the thermalized, lowest-energy, emitting exciton. We discuss the occurrence of hot carrier processes that are common to photoionization, luminescence blinking, and the fast transient optical absorption that is associated with multiple exciton generation MEG studies.

  11. Detection of amino acid neurotransmitters by surface enhanced Raman scattering and hollow core photonic crystal fiber

    Science.gov (United States)

    Tiwari, Vidhu S.; Khetani, Altaf; Monfared, Ali Momenpour T.; Smith, Brett; Anis, Hanan; Trudeau, Vance L.

    2012-03-01

    The present work explores the feasibility of using surface enhanced Raman scattering (SERS) for detecting the neurotransmitters such as glutamate (GLU) and gamma-amino butyric acid (GABA). These amino acid neurotransmitters that respectively mediate fast excitatory and inhibitory neurotransmission in the brain, are important for neuroendocrine control, and upsets in their synthesis are also linked to epilepsy. Our SERS-based detection scheme enabled the detection of low amounts of GLU (10-7 M) and GABA (10-4 M). It may complement existing techniques for characterizing such kinds of neurotransmitters that include high-performance liquid chromatography (HPLC) or mass spectrography (MS). This is mainly because SERS has other advantages such as ease of sample preparation, molecular specificity and sensitivity, thus making it potentially applicable to characterization of experimental brain extracts or clinical diagnostic samples of cerebrospinal fluid and saliva. Using hollow core photonic crystal fiber (HC-PCF) further enhanced the Raman signal relative to that in a standard cuvette providing sensitive detection of GLU and GABA in micro-litre volume of aqueous solutions.

  12. A heat transfer correlation based on a surface renewal model for molten core concrete interaction study

    International Nuclear Information System (INIS)

    Tourniaire, B. . E-mail bruno.tourniaire@cea.fr

    2006-01-01

    The prediction of heat transfer between corium pool and concrete basemat is of particular significance in the framework of the study of PWR's severe accident. Heat transfer directly governs the ablation velocity of concrete in case of molten core concrete interaction (MCCI) and, consequently, the time delay when the reactor cavity may fail. From a restricted hydrodynamic point of view, this issue is related to heat transfer between a heated bubbling pool and a porous wall with gas injection. Several experimental studies have been performed with simulant materials and many correlations have been provided to address this issue. The comparisons of the results of these correlations with the measurements and their extrapolation to reactor materials show that strong discrepancies between the results of these models are obtained which probably means that some phenomena are not well taken into account. The main purpose of this paper is to present an alternative heat transfer model which was originally developed for chemical engineering applications (bubble columns) by Deckwer. A part of this work is devoted to the presentation of this model, which is based on a surface renewal assumption. Comparison of the results of this model with available experimental data in different systems are presented and discussed. These comparisons clearly show that this model can be used to deal with the particular problem of MCCI. The analyses also lead to enrich the original model by taking into account the thermal resistance of the wall: a new formulation of the Deckwer's correlation is finally proposed

  13. SNR 2 core dynamics and shut-down signals in a protected loss-of-flow incident

    International Nuclear Information System (INIS)

    Kleefeldt, K.

    1982-01-01

    The dynamic behavior of a 1300 MWe Core during a loss-of-flow incident has been analyzed by use of the SAS3D code for a given pump coast down characteristic and constant core inlet temperature. Emphasis was placed on the questions: How fast and via which monitored parameters can the incident be recognized by the reactor protection system. What is the tolerable time span for the shut-down action without exceeding safety limits. Key prameters and limit values as well as conceivable reactivity feed-back effects are discussed. The result is, that three out of four choosen monitored parameters are capable of initiating a shut-down action in time. In addition, the amount of shut-down reactivity required for a successful scram was briefly investigated

  14. A method for the experimental determination of surface photoemission core-level shifts for 3d transition metals

    NARCIS (Netherlands)

    Shamsutdinov, N.R.; Sloof, W.G.; Böttger, A.J.

    2005-01-01

    A method is presented to determine the photoelectron surface core-level shift (SCLS) of 3d transition metals using x-ray photoelectron spectroscopy. The experimental difficulties arising from the relatively large broadening of photoemission lines in the 3d transition series can be overcome by the

  15. The Effect of the Holes Size Change of Lower-Support-Structure-Bottom Plate on the Reactor Core-Inlet Flow-Distribution

    International Nuclear Information System (INIS)

    Lee, Gong Hee; Bang, Young Seok; Cheong, Ae Ju

    2015-01-01

    Complex thermal-hydraulic phenomena exist inside PWR because reactor interiors include a fuel assembly, control rod assembly, ICI (In-Core Instrumentation), and other internal structures. Because changes to reactor design may influence interior, thermal-hydraulic characteristics, licensing applicants commonly conduct a flow-distribution test and use test results (e.g., core-inlet flow-rate distribution) as the input data for a core thermal-margin analysis program. Because the APR+ (Advanced Power Reactor Plus) had more fuel assemblies (241EA → 257EA) and the design of some internal structures was changed (from those of APR1400), the core-inlet flow-rate distribution for a 1/5 scaled-down reactor model was measured and high flow-rates were found especially near the outer region of the reactor core. In this study, to examine the effect of the holes size change (i.e. smaller diameter) in the outer region of the LSSBP, not a 50% blockage of the flow holes, on the reactor core-inlet flow-distribution, simulations were conducted with the commercial CFD (Computational Fluid Dynamics) software, ANSYS CFX R.14. The predicted results were compared with those of the original LSSBP. In this study, to examine the effect of the holes size change (smaller diameter) in the outer region of the LSSBP on the reactor core-inlet flow-distribution, simulations were conducted with the commercial CFD software, ANSYS CFX R.14. The predicted results were compared with those of the original LSSBP. Through these comparisons it was concluded that a more uniform distribution of the mass-flow rate at the core-inlet plane could be obtained by reducing the holes size in the outer region of the LSSBP

  16. Experimental and numerical studies on free surface flow of windowless target

    International Nuclear Information System (INIS)

    Su, G.Y.; Gu, H.Y.; Cheng, X.

    2012-01-01

    Highlights: ► Experimental and CFD studies on free surface flow have been performed in a scaled windowless target. ► Flow structure inside spallation area can be divided into three typical zones. ► Under large Reynolds number, large scale vortex can be observed. ► CFD studies have been conducted by using both LES and RANS (k-ω SST) turbulence models. ► LES model provides better numerical prediction on free surface behavior and flow transient. - Abstract: The formation and control method of the coolant free surface is one of the key technologies for the design of windowless targets in the accelerator driven system (ADS). In the recent study, experimental and numerical investigations on the free surface flow have been performed in a scaled windowless target by using water as the model fluid. The planar laser induced fluorescence technique has been applied to visualize the free surface flow pattern inside the spallation area. Experiments have been carried out with the Reynolds number in the range of 30,000–50,000. The structure and features of flow vortex have been investigated. The experimental results show that the free surface is vulnerable to the vortex movement. In addition, CFD simulations have been performed under the experimental conditions, using LES and RANS (k-ω SST) turbulence models, respectively. The numerical results of LES model agree qualitatively well with the experimental data related to both flow pattern and free surface behavior.

  17. Impact of the surface wind flow on precipitation characteristics over the southern Himalayas: GPM observations

    Science.gov (United States)

    Zhang, Aoqi; Fu, Yunfei; Chen, Yilun; Liu, Guosheng; Zhang, Xiangdong

    2018-04-01

    The distribution and influence of precipitation over the southern Himalayas have been investigated on regional and global scales. However, previous studies have been limited by the insufficient emphasis on the precipitation triggers or the lack of droplet size distribution (DSD) data. Here, precipitating systems were identified using Global Precipitation Mission dual-frequency radar data, and then categorized into five classes according to surface flow from the European Centre for Medium-Range Weather Forecast Interim data. The surface flow is introduced to indicate the precipitation triggers, which is validated in this study. Using case and statistical analysis, we show that the precipitating systems with different surface flow had different precipitation characteristics, including spatio-temporal features, reflectivity profile, DSD, and rainfall intensity. Furthermore, the results show that the source of the surface flow influences the intensity and DSD of precipitation. The terrain exerts different impacts on the precipitating systems of five categories, leading to various distributions of precipitation characteristics over the southern Himalayas. Our results suggest that the introduction of surface flow and DSD for precipitating systems provides insight into the complex precipitation of the southern Himalayas. The different characteristics of precipitating systems may be caused by the surface flow. Therefore, future study on the orographic precipitations should take account the impact of the surface flow and its relevant dynamic mechanism.

  18. Correlation of Water Frost Porosity in Laminar Flow over Flat Surfaces

    Science.gov (United States)

    Kandula, Max

    2011-01-01

    A dimensionless correlation has been proposed for water frost porosity expressing its dependence on frost surface temperature and Reynolds number for laminar forced flow over a flat surface. The correlation is presented in terms of a dimensionless frost surface temperature scaled with the cold plate temperature, and the freezing temperature. The flow Reynolds number is scaled with reference to the critical Reynolds number for laminar-turbulent transition. The proposed correlation agrees satisfactorily with the simultaneous measurements of frost density and frost surface temperature covering a range of plate temperature, ambient air velocity, humidity, and temperature. It is revealed that the frost porosity depends primarily on the frost surface and the plate temperatures and the flow Reynolds number, and is only weakly dependent on the relative humidity. The results also point out the general character of frost porosity displaying a decrease with an increase in flow Reynolds number.

  19. Experimental study of lithium free-surface flow for IFMIF target design

    International Nuclear Information System (INIS)

    Kondo, H.; Fujisato, A.; Yamaoka, N.; Inoue, S.; Miyamoto, S.; Iida, T.; Nakamura, H.; Ida, M.; Matushita, I.; Muroga, T.; Horiike, H.

    2006-01-01

    Lithium free-surface flow experiments to verify the design of IFMIF target have been carried out at Osaka University. The present report summarizes experimental results of surface phenomena, and cavitation characteristics of the loop, so as to try to apply these results to design parameters. Waves on the lithium flow surface is similar to that on water, and can be predicted by a linear stability theory. The wave amplitude is measured by an electro-contact probe. Surface roughness on a target nozzle, caused for example by attached chemical compounds and/or wastages by erosion and corrosion, can lead to a significant loss of target flow stability as well as surface wakes. The need of a polishing manipulator or exchange of the nozzle may be anticipated. Cavitation characteristic of the loop was measured by an accelerometer. From the results, a friction factor could be estimated fort he lithium flow

  20. The questions of liquid metal two-phase flow modelling in the FBR core channels

    International Nuclear Information System (INIS)

    Martsiniouk, D.Ye.; Sorokin, A.P.

    2000-01-01

    The two-fluid model representation for calculations of two-phase flow characteristics in the FBR fuel pin bundles with liquid metal cooling is presented and analysed. Two conservation equations systems of the mass, momentum and energy have been written for each phase. Components accounted the mass-, momentum- and heat transfer throughout the interface occur in the macro-field equations after the averaging procedure realisation. The pattern map and correlations for two-fluid model in vertical liquid metal flows are presented. The description of processes interphase mass- and heat exchange and interphase friction is determined by the two-phase flow regime. The opportunity of the liquid metal two-phase flow regime definition is analysed. (author)

  1. Micro-PIV/LIF measurements on electrokinetically-driven flow in surface modified microchannels

    International Nuclear Information System (INIS)

    Ichiyanagi, Mitsuhisa; Sasaki, Seiichi; Sato, Yohei; Hishida, Koichi

    2009-01-01

    Effects of surface modification patterning on flow characteristics were investigated experimentally by measuring electroosmotic flow velocities, which were obtained by micron-resolution particle image velocimetry using a confocal microscope. The depth-wise velocity was evaluated by using the continuity equation and the velocity data. The microchannel was composed of a poly(dimethylsiloxane) chip and a borosilicate cover-glass plate. Surface modification patterns were fabricated by modifying octadecyltrichlorosilane (OTS) on the glass surface. OTS can decrease the electroosmotic flow velocity compared to the velocity in the glass microchannel. For the surface charge varying parallel to the electric field, the depth-wise velocity was generated at the boundary area between OTS and the glass surfaces. For the surface charge varying perpendicular to the electric field, the depth-wise velocity did not form because the surface charge did not vary in the stream-wise direction. The surface charge pattern with the oblique stripes yielded a three-dimensional flow in a microchannel. Furthermore, the oblique patterning was applied to a mixing flow field in a T-shaped microchannel, and mixing efficiencies were evaluated from heterogeneity degree of fluorescent dye intensity, which was obtained by laser-induced fluorescence. It was found that the angle of the oblique stripes is an important factor to promote the span-wise and depth-wise momentum transport and contributes to the mixing flow in a microchannel

  2. Low-Flow Film Boiling Heat Transfer on Vertical Surfaces

    DEFF Research Database (Denmark)

    Munthe Andersen, J. G.; Dix, G. E.; Leonard, J. E.

    1976-01-01

    The phenomenon of film boiling heat transfer for high wall temperatures has been investigated. Based on the assumption of laminar flow for the film, the continuity, momentum, and energy equations for the vapor film are solved and a Bromley-type analytical expression for the heat transfer...... length, an average film boiling heat transfer coefficient is obtained....

  3. Mass transfer from smooth alabaster surfaces in turbulent flows

    Science.gov (United States)

    Opdyke, Bradley N.; Gust, Giselher; Ledwell, James R.

    1987-11-01

    The mass transfer velocity for alabaster plates in smooth-wall turbulent flow is found to vary with the friction velocity according to an analytic solution of the advective diffusion equation. Deployment of alabaster plates on the sea floor can perhaps be used to estimate the viscous stress, and transfer velocities for other species.

  4. Multiscale Finite Element Methods for Flows on Rough Surfaces

    KAUST Repository

    Efendiev, Yalchin

    2013-01-01

    In this paper, we present the Multiscale Finite Element Method (MsFEM) for problems on rough heterogeneous surfaces. We consider the diffusion equation on oscillatory surfaces. Our objective is to represent small-scale features of the solution via multiscale basis functions described on a coarse grid. This problem arises in many applications where processes occur on surfaces or thin layers. We present a unified multiscale finite element framework that entails the use of transformations that map the reference surface to the deformed surface. The main ingredients of MsFEM are (1) the construction of multiscale basis functions and (2) a global coupling of these basis functions. For the construction of multiscale basis functions, our approach uses the transformation of the reference surface to a deformed surface. On the deformed surface, multiscale basis functions are defined where reduced (1D) problems are solved along the edges of coarse-grid blocks to calculate nodalmultiscale basis functions. Furthermore, these basis functions are transformed back to the reference configuration. We discuss the use of appropriate transformation operators that improve the accuracy of the method. The method has an optimal convergence if the transformed surface is smooth and the image of the coarse partition in the reference configuration forms a quasiuniform partition. In this paper, we consider such transformations based on harmonic coordinates (following H. Owhadi and L. Zhang [Comm. Pure and Applied Math., LX(2007), pp. 675-723]) and discuss gridding issues in the reference configuration. Numerical results are presented where we compare the MsFEM when two types of deformations are used formultiscale basis construction. The first deformation employs local information and the second deformation employs a global information. Our numerical results showthat one can improve the accuracy of the simulations when a global information is used. © 2013 Global-Science Press.

  5. Experimental study on two-phase flow natural circulation in a core catcher cooling channel for EU-APR1400 using air-water system

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Won [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Nguyen, Thanh Hung [School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906 (United States); Ha, Kwang Soon; Kim, Hwan Yeol; Song, Jinho [Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Park, Hyun Sun [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Revankar, Shripad T., E-mail: shripad@postech.ac.kr [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906 (United States); Kim, Moo Hwan [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Korea Institute of Nuclear Safety, Daejeon 305-338 (Korea, Republic of)

    2017-05-15

    Highlights: • Two-phase flow regimes and transition behavior were observed in the coolant channel. • Test were conducted for natural circulation with air-water. • Data were obtained on flow regime, void fraction, flow rates and re-wetting time. • The data were related to a cooling capability of core catcher system. - Abstract: Ex-vessel core catcher cooling system driven by natural circulation is designed using a full scaled air-water system. A transparent half symmetric section of a core catcher coolant channel of a pressurized water reactor was designed with instrumentations for local void fraction measurement and flow visualization. Two designs of air-water top separator water tanks are studied including one with modified ‘super-step’ design which prevents gas entrainment into down-comer. In the experiment air flow rates are set corresponding to steam generation rate for given corium decay power. Measurements of natural circulation flow rate, spatial local void fraction distribution and re-wetting time near the top wall are carried out for various air flow rates which simulate boiling-induced vapor generation. Since heat transfer and critical heat flux are strongly dependent on the water mass flow rate and development of two-phase flow on the heated wall, knowledge of two-phase flow characteristics in the coolant channel is essential. Results on flow visualization showing two phase flow structure specifically near the high void accumulation regions, local void profiles, rewetting time, and natural circulation flow rate are presented for various air flow rates that simulate corium power levels. The data are useful in assessing the cooling capability of and safety of the core catcher system.

  6. The effect of surface-bulk potential difference on the kinetics of intercalation in core-shell active cathode particles

    Science.gov (United States)

    Kazemiabnavi, Saeed; Malik, Rahul; Orvananos, Bernardo; Abdellahi, Aziz; Ceder, Gerbrand; Thornton, Katsuyo

    2018-04-01

    Surface modification of active cathode particles is commonly observed in battery research as either a surface phase evolving during the cycling process, or intentionally engineered to improve capacity retention, rate capability, and/or thermal stability of the cathode material. Here, a continuum-scale model is developed to simulate the galvanostatic charge/discharge of a cathode particle with core-shell heterostructure. The particle is assumed to be comprised of a core material encapsulated by a thin layer of a second phase that has a different open-circuit voltage. The effect of the potential difference between the surface and bulk phases (Ω) on the kinetics of lithium intercalation and the galvanostatic charge/discharge profiles is studied at different values of Ω, C-rates, and exchange current densities. The difference between the Li chemical potential in the surface and bulk phases of the cathode particle results in a concentration difference between these two phases. This leads to a charge/discharge asymmetry in the galvanostatic voltage profiles, causing a decrease in the accessible capacity of the particle. These effects are more significant at higher magnitudes of surface-bulk potential difference. The proposed model provides detailed insight into the kinetics and voltage behavior of the intercalation/de-intercalation processes in core-shell heterostructure cathode particles.

  7. Experimental Study on Momentum Transfer of Surface Texture in Taylor-Couette Flow

    Science.gov (United States)

    Xue, Yabo; Yao, Zhenqiang; Cheng, De

    2017-05-01

    The behavior of Taylor-Couette (TC) flow has been extensively studied. However, no suitable torque prediction models exist for high-capacity fluid machinery. The Eckhardt-Grossmann-Lohse (EGL) theory, derived based on the Navier-Stokes equations, is proposed to model torque behavior. This theory suggests that surfaces are the significant energy transfer interfaces between cylinders and annular flow. This study mainly focuses on the effects of surface texture on momentum transfer behavior through global torque measurement. First, a power-law torque behavior model is built to reveal the relationship between dimensionless torque and the Taylor number based on the EGL theory. Second, TC flow apparatus is designed and built based on the CNC machine tool to verify the torque behavior model. Third, four surface texture films are tested to check the effects of surface texture on momentum transfer. A stereo microscope and three-dimensional topography instrument are employed to analyze surface morphology. Global torque behavior is measured by rotating a multi component dynamometer, and the effects of surface texture on the annular flow behavior are observed via images obtained using a high-speed camera. Finally, torque behaviors under four different surface conditions are fitted and compared. The experimental results indicate that surface textures have a remarkable influence on torque behavior, and that the peak roughness of surface texture enhances the momentum transfer by strengthening the fluctuation in the TC flow.

  8. Response of surface buoy moorings in steady and wave flows

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, N.M.; Nayak, B.U.; SanilKumar, V.

    A numerical model has been developed to evaluate the dynamics of surface buoy mooring systems under wave and current loading. System tension response and variation of tension in the mooring line at various depths have been evaluated for deep water...

  9. Modelling free surface flows with smoothed particle hydrodynamics

    Directory of Open Access Journals (Sweden)

    L.Di G.Sigalotti

    2006-01-01

    Full Text Available In this paper the method of Smoothed Particle Hydrodynamics (SPH is extended to include an adaptive density kernel estimation (ADKE procedure. It is shown that for a van der Waals (vdW fluid, this method can be used to deal with free-surface phenomena without difficulties. In particular, arbitrary moving boundaries can be easily handled because surface tension is effectively simulated by the cohesive pressure forces. Moreover, the ADKE method is seen to increase both the accuracy and stability of SPH since it allows the width of the kernel interpolant to vary locally in a way that only the minimum necessary smoothing is applied at and near free surfaces and sharp fluid-fluid interfaces. The method is robust and easy to implement. Examples of its resolving power are given for both the formation of a circular liquid drop under surface tension and the nonlinear oscillation of excited drops.

  10. Rotating polygon instability of a swirling free surface flow

    DEFF Research Database (Denmark)

    Tophøj, Laust Emil Hjerrild; Bohr, Tomas; Mougel, J.

    2013-01-01

    We explain the rotating polygon instability on a swirling fluid surface [G. H. Vatistas, J. Fluid Mech. 217, 241 (1990)JFLSA70022-1120 and Jansson et al., Phys. Rev. Lett. 96, 174502 (2006)PRLTAO0031-9007] in terms of resonant interactions between gravity waves on the outer part of the surface...... behavior near the corners), and indeed we show that we can obtain the polygons transiently by violently stirring liquid nitrogen in a hot container....

  11. A New Method to Simulate Free Surface Flows for Viscoelastic Fluid

    Directory of Open Access Journals (Sweden)

    Yu Cao

    2015-01-01

    Full Text Available Free surface flows arise in a variety of engineering applications. To predict the dynamic characteristics of such problems, specific numerical methods are required to accurately capture the shape of free surface. This paper proposed a new method which combined the Arbitrary Lagrangian-Eulerian (ALE technique with the Finite Volume Method (FVM to simulate the time-dependent viscoelastic free surface flows. Based on an open source CFD toolbox called OpenFOAM, we designed an ALE-FVM free surface simulation platform. In the meantime, the die-swell flow had been investigated with our proposed platform to make a further analysis of free surface phenomenon. The results validated the correctness and effectiveness of the proposed method for free surface simulation in both Newtonian fluid and viscoelastic fluid.

  12. Decorin core protein (decoron) shape complements collagen fibril surface structure and mediates its binding.

    Science.gov (United States)

    Orgel, Joseph P R O; Eid, Aya; Antipova, Olga; Bella, Jordi; Scott, John E

    2009-09-15

    Decorin is the archetypal small leucine rich repeat proteoglycan of the vertebrate extracellular matrix (ECM). With its glycosaminoglycuronan chain, it is responsible for stabilizing inter-fibrillar organization. Type I collagen is the predominant member of the fibrillar collagen family, fulfilling both organizational and structural roles in animal ECMs. In this study, interactions between decoron (the decorin core protein) and binding sites in the d and e(1) bands of the type I collagen fibril were investigated through molecular modeling of their respective X-ray diffraction structures. Previously, it was proposed that a model-based, highly curved concave decoron interacts with a single collagen molecule, which would form extensive van der Waals contacts and give rise to strong non-specific binding. However, the large well-ordered aggregate that is the collagen fibril places significant restraints on modes of ligand binding and necessitates multi-collagen molecular contacts. We present here a relatively high-resolution model of the decoron-fibril collagen complex. We find that the respective crystal structures complement each other well, although it is the monomeric form of decoron that shows the most appropriate shape complementarity with the fibril surface and favorable calculated energies of interaction. One molecule of decoron interacts with four to six collagen molecules, and the binding specificity relies on a large number of hydrogen bonds and electrostatic interactions, primarily with the collagen motifs KXGDRGE and AKGDRGE (d and e(1) bands). This work helps us to understand collagen-decorin interactions and the molecular architecture of the fibrillar ECM in health and disease.

  13. Decorin core protein (decoron shape complements collagen fibril surface structure and mediates its binding.

    Directory of Open Access Journals (Sweden)

    Joseph P R O Orgel

    2009-09-01

    Full Text Available Decorin is the archetypal small leucine rich repeat proteoglycan of the vertebrate extracellular matrix (ECM. With its glycosaminoglycuronan chain, it is responsible for stabilizing inter-fibrillar organization. Type I collagen is the predominant member of the fibrillar collagen family, fulfilling both organizational and structural roles in animal ECMs. In this study, interactions between decoron (the decorin core protein and binding sites in the d and e(1 bands of the type I collagen fibril were investigated through molecular modeling of their respective X-ray diffraction structures. Previously, it was proposed that a model-based, highly curved concave decoron interacts with a single collagen molecule, which would form extensive van der Waals contacts and give rise to strong non-specific binding. However, the large well-ordered aggregate that is the collagen fibril places significant restraints on modes of ligand binding and necessitates multi-collagen molecular contacts. We present here a relatively high-resolution model of the decoron-fibril collagen complex. We find that the respective crystal structures complement each other well, although it is the monomeric form of decoron that shows the most appropriate shape complementarity with the fibril surface and favorable calculated energies of interaction. One molecule of decoron interacts with four to six collagen molecules, and the binding specificity relies on a large number of hydrogen bonds and electrostatic interactions, primarily with the collagen motifs KXGDRGE and AKGDRGE (d and e(1 bands. This work helps us to understand collagen-decorin interactions and the molecular architecture of the fibrillar ECM in health and disease.

  14. Refined model for the coolability of core debris with flow entry from the bottom

    International Nuclear Information System (INIS)

    Schulenberg, T.; Mueller, U.

    1986-01-01

    Within the context of a hypothetical severe accident in light water reactors also heat generating debris beds of a coarse particle size are discussed. A refined model for two-phase flow in particle beds is presented. Compared to previous models this model takes into account the effect of interfacial drag forces between liquid and vapor. These effects are important in coarse debris beds. The model is based on the momentum equations for separated flow, which are closed by empirical relations for the wall shear stress and the interfacial drag. When the refined model is applied to LWR severe accident scenarios an increased dryout heat flux is predicted for debris beds with flow entry from the bottom driven by a moderate downcomer head

  15. Magnetic Fe{sub 3}O{sub 4}-Au core-shell nanostructures for surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, D.A.; Adams, S.A.; Zhang, J.Z. [Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Lopez-Luke, T. [Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Cento de Investigaciones en Optica, A.P. 1-948 Leon, Gto. 37150 (Mexico); Torres-Castro, A. [Universidad Autonoma de Nuevo Leon, A.P. 126-F, Monterrey, NL, 66450 (Mexico)

    2012-11-15

    The synthesis, structural and optical characterization, and application of superparamagnetic and water-dispersed Fe{sub 3}O{sub 4}-Au core-shell nanoparticles for surface enhanced Raman scattering (SERS) is reported. The structure of the nanoparticles was determined by scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). STEM images of the Fe{sub 3}O{sub 4}-Au core-shell nanoparticles reveal an average diameter of 120 nm and a high degree of surface roughness. The nanoparticles, which display superparamagnetic properties due to the core Fe{sub 3}O{sub 4} material, exhibit a visible surface plasmon resonance (SPR) peaked at 580 nm due to the outer gold shell. The nanoparticles are used as a substrate for surface enhanced Raman scattering (SERS) with rhodamine 6G (R6G) as a Raman reporter molecule. The SERS enhancement factor is estimated to be on the order of 10{sup 6}, which is {proportional_to} 2 times larger than that of conventional gold nanoparticles (AuNPs) under similar conditions. Significantly, magnetically-induced aggregation of the Fe{sub 3}O{sub 4}-Au core-shell nanoparticles substantially enhanced SERS activity compared to non-magnetically-aggregated Fe{sub 3}O{sub 4}-Au nanoparticles. This is attributed to both increased scattering from the aggregates as well as ''hot spots'' due to more junction sites in the magnetically-induced aggregates. The magnetic properties of the Fe{sub 3}O{sub 4} core, coupled with the optical properties of the Au shell, make the Fe{sub 3}O{sub 4}-Au nanoparticles unique for various potential applications including biological sensing and therapy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Modeling of surface roughness effects on Stokes flow in circular pipes

    Science.gov (United States)

    Song, Siyuan; Yang, Xiaohu; Xin, Fengxian; Lu, Tian Jian

    2018-02-01

    Fluid flow and pressure drop across a channel are significantly influenced by surface roughness on a channel wall. The present study investigates the effects of periodically structured surface roughness upon flow field and pressure drop in a circular pipe at low Reynolds numbers. The periodic roughness considered exhibits sinusoidal, triangular, and rectangular morphologies, with the relative roughness (i.e., ratio of the amplitude of surface roughness to hydraulic diameter of the pipe) no more than 0.2. Based upon a revised perturbation theory, a theoretical model is developed to quantify the effect of roughness on fully developed Stokes flow in the pipe. The ratio of static flow resistivity and the ratio of the Darcy friction factor between rough and smooth pipes are expressed in four-order approximate formulations, which are validated against numerical simulation results. The relative roughness and the wave number are identified as the two key parameters affecting the static flow resistivity and the Darcy friction factor.

  17. Prediction of the surface roughness of AA6082 flow-formed tubes by design of experiments

    International Nuclear Information System (INIS)

    Srinivasulu, M.; Komaraiah, M.; Rao, C. S. Krishna Prasada

    2013-01-01

    Flow forming is a modern, chipless metal forming process that is employed for the production of thin-walled seamless tubes. Experiments are conducted on AA6082 alloy pre-forms to flow form into thin-walled tubes on a CNC flow-forming machine with a single roller. Design of experiments is used to predict the surface roughness of flow-formed tubes. The process parameters selected for this study are the roller axial feed, mandrel speed, and roller radius. A standard response surface methodology (RSM) called the Box Behnken design is used to perform the experimental runs. The regression model developed by RSM successfully predicts the surface roughness of AA6082 flow-formed tubes within the range of the selected process parameters.

  18. Prediction of the surface roughness of AA6082 flow-formed tubes by design of experiments

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasulu, M. [Government Polytechnic for Women Badangpet, Hyderabad (India); Komaraiah, M. [Sreenidhi Institute of Science and Technology, Hyderabad (India); Rao, C. S. Krishna Prasada [Bharat Dynamics Limited, Hyderabad (India)

    2013-06-15

    Flow forming is a modern, chipless metal forming process that is employed for the production of thin-walled seamless tubes. Experiments are conducted on AA6082 alloy pre-forms to flow form into thin-walled tubes on a CNC flow-forming machine with a single roller. Design of experiments is used to predict the surface roughness of flow-formed tubes. The process parameters selected for this study are the roller axial feed, mandrel speed, and roller radius. A standard response surface methodology (RSM) called the Box Behnken design is used to perform the experimental runs. The regression model developed by RSM successfully predicts the surface roughness of AA6082 flow-formed tubes within the range of the selected process parameters.

  19. Two-phase flow experiments in emergency core cooling feed through the hot leg for developing numerical models

    International Nuclear Information System (INIS)

    Staebler, T.; Meyer, L.; Schulenberg, T.; Laurien, E.

    2006-01-01

    When a leakage, a 'loss-of-coolant accident', occurs in a light water reactor, the emergency cooling system is able to supply large amounts of coolant to ensure residual heat removal. This supply can be routed through a special emergency cooling pipe, the 'scoop', into the horizontal section of the main coolant pipe, the 'hot leg'. At the same time, hot steam from the superheated, partly voided core flows against the coolant. This gives rise to a two-phase flow in the opposite direction. A factor of primary interest in this situation is whether the coolant supplied by the emergency cooling system will reach the reactor core. The research project is being conducted in order to compute the rate of water supply by numerical methods. The WENKA test facility has been designed and built at the Karlsruhe Research Center to verify numerical calculations. It can be used to study the fluid dynamics phenomena expected to arise in emergency coolant feeding into the hot leg; the necessary local data can be determined experimentally. An extensive database for validating the numerical calculations is then available to complete the experimental work. (orig.)

  20. High-resolution continuous flow analysis setup for water isotopic measurement from ice cores using laser spectroscopy

    Science.gov (United States)

    Emanuelsson, B. D.; Baisden, W. T.; Bertler, N. A. N.; Keller, E. D.; Gkinis, V.

    2014-12-01

    Here we present an experimental setup for water stable isotopes (δ18O and δD) continuous flow measurements. It is the first continuous flow laser spectroscopy system that is using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS; analyzer manufactured by Los Gatos Research - LGR) in combination with an evaporation unit to continuously analyze sample from an ice core. A Water Vapor Isotopic Standard Source (WVISS) calibration unit, manufactured by LGR, was modified to: (1) increase the temporal resolution by reducing the response time (2) enable measurements on several water standards, and (3) to reduce the influence from memory effects. While this setup was designed for the Continuous Flow Analysis (CFA) of ice cores, it can also continuously analyze other liquid or vapor sources. The modified setup provides a shorter response time (~54 and 18 s for 2013 and 2014 setup, respectively) compared to the original WVISS unit (~62 s), which is an improvement in measurement resolution. Another improvement compared to the original WVISS is that the modified setup has a reduced memory effect. Stability tests comparing the modified WVISS and WVISS setups were performed and Allan deviations (σAllan) were calculated to determine precision at different averaging times. For the 2013 modified setup the precision after integration times of 103 s are 0.060 and 0.070‰ for δ18O and δD, respectively. For the WVISS setup the corresponding σAllan values are 0.030, 0.060 and 0.043‰ for δ18O, δD and δ17O, respectively. For the WVISS setup the precision is 0.035, 0.070 and 0.042‰ after 103 s for δ18O, δD and δ17O, respectively. Both the modified setups and WVISS setup are influenced by instrumental drift with δ18O being more drift sensitive than δD. The σAllan values for δ18O of 0.30 and 0.18‰ for the modified (2013) and WVISS setup, respectively after averaging times of 104 s (2.78 h). The Isotopic Water Analyzer (IWA)-modified WVISS setup used during the

  1. Effects of core strength training using stable versus unstable surfaces on physical fitness in adolescents: a randomized controlled trial.

    Science.gov (United States)

    Granacher, Urs; Schellbach, Jörg; Klein, Katja; Prieske, Olaf; Baeyens, Jean-Pierre; Muehlbauer, Thomas

    2014-01-01

    It has been demonstrated that core strength training is an effective means to enhance trunk muscle strength (TMS) and proxies of physical fitness in youth. Of note, cross-sectional studies revealed that the inclusion of unstable elements in core strengthening exercises produced increases in trunk muscle activity and thus provide potential extra training stimuli for performance enhancement. Thus, utilizing unstable surfaces during core strength training may even produce larger performance gains. However, the effects of core strength training using unstable surfaces are unresolved in youth. This randomized controlled study specifically investigated the effects of core strength training performed on stable surfaces (CSTS) compared to unstable surfaces (CSTU) on physical fitness in school-aged children. Twenty-seven (14 girls, 13 boys) healthy subjects (mean age: 14 ± 1 years, age range: 13-15 years) were randomly assigned to a CSTS (n = 13) or a CSTU (n = 14) group. Both training programs lasted 6 weeks (2 sessions/week) and included frontal, dorsal, and lateral core exercises. During CSTU, these exercises were conducted on unstable surfaces (e.g., TOGU© DYNAIR CUSSIONS, THERA-BAND© STABILITY TRAINER). Significant main effects of Time (pre vs. post) were observed for the TMS tests (8-22%, f = 0.47-0.76), the jumping sideways test (4-5%, f = 1.07), and the Y balance test (2-3%, f = 0.46-0.49). Trends towards significance were found for the standing long jump test (1-3%, f = 0.39) and the stand-and-reach test (0-2%, f = 0.39). We could not detect any significant main effects of Group. Significant Time x Group interactions were detected for the stand-and-reach test in favour of the CSTU group (2%, f = 0.54). Core strength training resulted in significant increases in proxies of physical fitness in adolescents. However, CSTU as compared to CSTS had only limited additional effects (i.e., stand-and-reach test). Consequently, if the

  2. Surface zwitterionicalization of poly(vinylidene fluoride) membranes from the entrapped reactive core-shell silica nanoparticles.

    Science.gov (United States)

    Zhu, Li-Jing; Zhu, Li-Ping; Zhang, Pei-Bin; Zhu, Bao-Ku; Xu, You-Yi

    2016-04-15

    We demonstrate the preparation and properties of poly(vinylidene fluoride) (PVDF) filtration membranes modified via surface zwitterionicalization mediated by reactive core-shell silica nanoparticles (SiO2 NPs). The organic/inorganic hybrid SiO2 NPs grafted with poly(methyl meth acrylate)-block-poly(2-dimethylaminoethyl methacrylate) copolymer (PMMA-b-PDMAEMA) shell were prepared by surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization and then used as a membrane-making additive of PVDF membranes. The PDMAEMA exposed on membrane surface and pore walls were quaternized into zwitterionic poly(sulfobetaine methacrylate) (PSBMA) using 1,3-propane sultone (1,3-PS) as the quaternization agent. The membrane surface chemistry and morphology were analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The hydrophilicity, permeability and antifouling ability of the investigated membranes were evaluated in detail. It was found that the PSBMA chains brought highly-hydrophilic and strong fouling resistant characteristics to PVDF membranes due to the powerful hydration of zwitterionic surface. The SiO2 cores and PMMA chains in the hybrid NPs play a role of anchors for the linking of PSBMA chains to membrane surface. Compared to the traditional strategies for membrane hydrophilic modification, the developed method in this work combined the advantages of both blending and surface reaction. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Flow cytometry detection of planktonic cells with polycyclic aromatic hydrocarbons sorbed to cell surfaces

    KAUST Repository

    Cerezo, Maria I.; Linden, Matthew; Agusti, Susana

    2017-01-01

    Polycyclic aromatic hydrocarbons are very important components of oil pollution. These pollutants tend to sorb to cell surfaces, exerting toxic effects on organisms. Our study developed a flow cytometric method for the detection of PAHs sorbed

  4. A Variational Model for Two-Phase Immiscible Electroosmotic Flow at Solid Surfaces

    KAUST Repository

    Shao, Sihong; Qian, Tiezheng

    2012-01-01

    We develop a continuum hydrodynamic model for two-phase immiscible flows that involve electroosmotic effect in an electrolyte and moving contact line at solid surfaces. The model is derived through a variational approach based on the Onsager

  5. Direct numerical simulation of turbulent channel flow over a liquid-infused micro-grooved surface

    Science.gov (United States)

    Chang, Jaehee; Jung, Taeyong; Choi, Haecheon; Kim, John

    2016-11-01

    Recently a superhydrophobic surface has drawn much attention as a passive device to achieve high drag reduction. Despite the high performance promised at ideal conditions, maintaining the interface in real flow conditions is an intractable problem. A non-wetting surface, known as the slippery liquid-infused porous surface (SLIPS) or the lubricant-impregnated surface (LIS), has shown a potential for drag reduction, as the working fluid slips at the interface but cannot penetrate into the lubricant layer. In the present study, we perform direct numerical simulation of turbulent channel flow over a liquid-infused micro-grooved surface to investigate the effects of this surface on the interfacial slip and drag reduction. The flow rate of water is maintained constant corresponding to Reτ 180 in a fully developed turbulent channel flow, and the lubricant layer is shear-driven by the turbulent water flow. The lubricant layer is also simulated with the assumption that the interface is flat (i.e. the surface tension effect is neglected). The solid substrate in which the lubricant is infused is modelled as straight ridges using an immersed boundary method. DNS results show that drag reduction by the liquid-infused surface is highly dependent on the viscosity of the lubricant.

  6. Wind Characteristics of Coastal and Inland Surface Flows

    Science.gov (United States)

    Subramanian, Chelakara; Lazarus, Steven; Jin, Tetsuya

    2015-11-01

    Lidar measurements of the winds in the surface layer (up to 80 m) inland and near the beach are studied to better characterize the velocity profile and the effect of roughness. Mean and root-mean-squared profiles of horizontal and vertical wind components are analyzed. The effects of variable time (18, 60 and 600 seconds) averaging on the above profiles are discussed. The validity of common surface layer wind profile models to estimate skin friction drag is assessed in light of these measurements. Other turbulence statistics such as auto- and cross- correlations in spatial and temporal domains are also presented. The help of FIT DMES field measurement crew is acknowledged.

  7. A Kinematic Conservation Law in Free Surface Flow

    OpenAIRE

    Gavrilyuk , Sergey; Kalisch , Henrik; Khorsand , Zahra

    2015-01-01

    The Green-Naghdi system is used to model highly nonlinear weakly dispersive waves propagating at the surface of a shallow layer of a perfect fluid. The system has three associated conservation laws which describe the conservation of mass, momentum, and energy due to the surface wave motion. In addition, the system features a fourth conservation law which is the main focus of this note. It will be shown how this fourth conservation law can be interpreted in terms of a concrete kinematic quanti...

  8. A stereo vision method for tracking particle flow on the weld pool surface

    NARCIS (Netherlands)

    Zhao, C.X.; Richardson, I.M.; Kenjeres, S.; Kleijn, C.R.; Saldi, Z.

    2009-01-01

    The oscillation of a weld pool surface makes the fluid flow motion quite complex. Two-dimensional results cannot reflect enough information to quantitatively describe the fluid flow in the weld pool; however, there are few direct three-dimensional results available. In this paper, we describe a

  9. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

    2002-01-01

    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores

  10. Application of turbulence modeling to predict surface heat transfer in stagnation flow region of circular cylinder

    Science.gov (United States)

    Wang, Chi R.; Yeh, Frederick C.

    1987-01-01

    A theoretical analysis and numerical calculations for the turbulent flow field and for the effect of free-stream turbulence on the surface heat transfer rate of a stagnation flow are presented. The emphasis is on the modeling of turbulence and its augmentation of surface heat transfer rate. The flow field considered is the region near the forward stagnation point of a circular cylinder in a uniform turbulent mean flow. The free stream is steady and incompressible with a Reynolds number of the order of 10 to the 5th power and turbulence intensity of less than 5 percent. For this analysis, the flow field is divided into three regions: (1) a uniform free-stream region where the turbulence is homogeneous and isotropic; (2) an external viscid flow region where the turbulence is distorted by the variation of the mean flow velocity; and, (3) an anisotropic turbulent boundary layer region over the cylinder surface. The turbulence modeling techniques used are the kappa-epsilon two-equation model in the external flow region and the time-averaged turbulence transport equation in the boundary layer region. The turbulence double correlations, the mean velocity, and the mean temperature within the boundary layer are solved numerically from the transport equations. The surface heat transfer rate is calculated as functions of the free-stream turbulence longitudinal microlength scale, the turbulence intensity, and the Reynolds number.

  11. Simultaneous calibration of surface flow and baseflow simulations: A revisit of the SWAT model calibration framework

    Science.gov (United States)

    Accurate analysis of water flow pathways from rainfall to streams is critical for simulating water use, climate change impact, and contaminant transport. In this study, we developed a new scheme to simultaneously calibrate surface flow (SF) and baseflow (BF) simulations of Soil and Water Assessment ...

  12. Simultaneous measurement of a fluid flow and the fluid's free surface using PIV

    International Nuclear Information System (INIS)

    Philip, O.G.; Hassan, Y.A.; Okamoto, K.

    1995-01-01

    The objective of this investigation is to study the interaction between a fluid flow and its free surface with an improved application of the flow measurement technique, particle image velocimetry (PIV). In this study, improvements in the data acquisition and tracking method of the PIV technique were developed

  13. Cavity temperature and flow characteristics in a gas-core test reactor

    Science.gov (United States)

    Putre, H. A.

    1973-01-01

    A test reactor concept for conducting basic studies on a fissioning uranium plasma and for testing various gas-core reactor concepts is analyzed. The test reactor consists of a conventional fuel-element region surrounding a 61-cm-(2-ft-) diameter cavity region which contains the plasma experiment. The fuel elements provide the neutron flux for the cavity region. The design operating conditions include 60-MW reactor power, 2.7-MW cavity power, 200-atm cavity pressure, and an average uranium plasma temperature of 15,000 K. The analytical results are given for cavity radiant heat transfer, hydrogen transpiration cooling, and uranium wire or powder injection.

  14. The development of NRTM-turbine flow meter and measurement of the coolant flow rate in-core of 5 MW heating reactor

    International Nuclear Information System (INIS)

    Zha Meisheng; Wang Xiuqin; Ni Mengchen

    1995-01-01

    In order to measure the coolant flow rate in-core of 5 MW Heating Reactor the special turbine flowmeter of the type of NRTM has been developed. It consists of a body, a turbine with long screw blade and six pieces of Alnico magnets, and a coil mounted on the body. The advantage of this turbine flowmeter is of low resistance and long working-life. Another advantage is that when the turbine is working or not working its factor of resistance is about the same. It is very important for a natural circulation heating reactor. Because the cable, which is welded to the coil assembly, is long enough to extend out of the reactor vessel to the control room, the signal of flow rate is easy to be disturbed by noise in the case. The traditional method of counting the frequency of the A-C voltage which is induced in the coil has a poor ability for resisting noise. The method of the frequency-spectrum analysis of the frequency of the A-C voltage is used to make sure the accuracy of the measurement of the turbine flow meter. Compared with the method of the count it has a good ability for resisting noise. After three years operation a lot of valuable data were obtained

  15. Comparison of Experimental Surface and Flow Field Measurements to Computational Results of the Juncture Flow Model

    Science.gov (United States)

    Roozeboom, Nettie H.; Lee, Henry C.; Simurda, Laura J.; Zilliac, Gregory G.; Pulliam, Thomas H.

    2016-01-01

    Wing-body juncture flow fields on commercial aircraft configurations are challenging to compute accurately. The NASA Advanced Air Vehicle Program's juncture flow committee is designing an experiment to provide data to improve Computational Fluid Dynamics (CFD) modeling in the juncture flow region. Preliminary design of the model was done using CFD, yet CFD tends to over-predict the separation in the juncture flow region. Risk reduction wind tunnel tests were requisitioned by the committee to obtain a better understanding of the flow characteristics of the designed models. NASA Ames Research Center's Fluid Mechanics Lab performed one of the risk reduction tests. The results of one case, accompanied by CFD simulations, are presented in this paper. Experimental results suggest the wall mounted wind tunnel model produces a thicker boundary layer on the fuselage than the CFD predictions, resulting in a larger wing horseshoe vortex suppressing the side of body separation in the juncture flow region. Compared to experimental results, CFD predicts a thinner boundary layer on the fuselage generates a weaker wing horseshoe vortex resulting in a larger side of body separation.

  16. Advanced Instrumentation and Measurement Techniques for Near Surface Flows

    Science.gov (United States)

    Cadel, Daniel R.

    The development of aerodynamic boundary layers on wind turbine blades is an important consideration in their performance. It can be quite challenging to replicate full scale conditions in laboratory experiments, and advanced diagnostics become valuable in providing data not available from traditional means. A new variant of Doppler global velocimetry (DGV) known as cross-correlation DGV is developed to measure boundary layer profiles on a wind turbine blade airfoil in the large scale Virginia Tech Stability Wind Tunnel. The instrument provides mean velocity vectors with reduced sensitivity to external conditions, a velocity measurement range from 0 ms-1 to over 3000 ms-1, and an absolute uncertainty. Monte Carlo simulations with synthetic signals reveal that the processing routine approaches the Cramer-Rao lower bound in optimized conditions. A custom probe-beam technique is implanted to eliminate laser flare for measuring boundary layer profiles on a DU96-W-180 wind turbine airfoil model. Agreement is seen with laser Doppler velocimetry data within the uncertainty estimated for the DGV profile. Lessons learned from the near-wall flow diagnostics development were applied to a novel benchmark model problem incorporating the relevant physical mechanisms of the high amplitude periodic turbulent flow experienced by turbine blades in the field. The model problem is developed for experimentally motivated computational model development. A circular cylinder generates a periodic turbulent wake, in which a NACA 63215b airfoil with a chord Reynolds number Rec = 170,000 is embedded for a reduced frequency k = pi f c/V = 1.53. Measurements are performed with particle image velocimetry on the airfoil suction side and in highly magnified planes within the boundary layer. Outside of the viscous region, the Reynolds stress profile is consistent with the prediction of Rapid Distortion Theory (RDT), confirming that the redistribution of normal stresses is an inviscid effect. The

  17. Structure, Mechanics and Flow Properties of Fractured Shale: Core-Scale Experimentation and In-situ Imaging

    Science.gov (United States)

    Abdelmalek, B. F.; Karpyn, Z.; Liu, S.

    2014-12-01

    Over the last several years, hydrocarbon exploitation and development in North America has been heavily centered on shale gas plays. However, the physical attributes of shales and their manifestation on transport properties and storage capacity remain poorly understood. Therefore, more experimentally based data are needed to fill the gaps in understanding both transport and storage of fluids in shale. The proposed work includes installation and testing of an experimental system which is capable of monitoring the dynamic evolution of shale core permeability under variable loading conditions and in coordination with X-ray microCT imaging. The goal of this study is to better understand and quantify fluid flow patterns and associated transport dynamics of fractured shale samples. The independent variables considered in this study are: mechanical loading and pore pressure. The mechanical response of shale core is captured for different loading paths. To best replicate the in-situ production scenario, the pore pressure is progressively depleted to mimic pressure decline. During the course of experimentation, permeability is estimated using the pulse-decay method under tri-axial stress boundary conditions. Simultaneously, X-ray microCT imaging is used with a tracer gas that is allowed to flow through the sample as an illuminating agent. In the presence of an illuminating agent, either Xenon or Krypton, the X-ray CT scanner can image fractures, global pathways and diffusional fronts in the matrix, as well as sorption sites that reflect heterogeneities in the sample and localized deformation. Anticipated results from these experiments will help quantify permeability evolution as a function of different loading conditions and pore pressure depletion. Also, the X-ray images will help visualize the change of flow patterns and the intensity of sorption as a function of mechanical loading and pore pressure.

  18. Free-surface flow around an appended hull

    International Nuclear Information System (INIS)

    Lungu, A; Pacuraru, F

    2010-01-01

    The prediction of the total drag experienced by an advancing ship is a complicated problem which requires a thorough understanding of the hydrodynamic forces acting on the hull, the physical processes from which these forces arise as well as their mutual interaction. A general numerical method to predict the hydrodynamic performance of a twin-propeller combatant ship is presented in the paper, which describes the solution of a RANS solver coupled with a body force method as an attempt in investigating the flow features around the ship hull equipped with rotating propellers and rudders. A special focus is made on the propeller non-symmetrical inflow field, aimed at obtaining the necessary data for the propulsive performances evaluation as well as for the propeller final design. The reported work allows not only the performance evaluation for the overall performances of a hull, but also leads to the development, implementation and validation of new concepts in modeling the turbulent vortical flows, with direct connection to the ship propulsion problem.

  19. Segregating photoelastic particles in free-surface granular flows

    Science.gov (United States)

    Thomas, Amalia; Vriend, Nathalie; Environmental; Industrial Fluid Dynamics Team

    2017-11-01

    We present results from a novel experimental set-up creating 2D avalanches of photoelastic discs. Two distinct hoppers supply either monodisperse or bidisperse particles at adjustable flow-rates into a 2 meter long, narrow acrylic chute inclined at 20°. For 20-40 seconds the avalanche maintains a steady-state that accelerates and thins downstream. The chute basal roughness is variable, allowing for different flow profiles. Using a set of polarizers and a high-speed camera, we visualize and quantify the forces due to dynamic interactions between the discs using photoelastic theory. Velocity and density profiles are derived from particle tracking at different distances from the discharge point and are coarse-grained to obtain continuous fields. With the access to both force information and dynamical properties via particle-tracking, we can experimentally validate existing mu(I) and non-local rheologies. As an extension, we probe the effect of granular segregation in bimodal mixtures by using the two separate inflow hoppers. We derive the state of segregation along the avalanche channel and measure the segregation velocities of each species. This provides insight in, and a unique validation of, the fundamental physical processes that drive segregation in avalanching geometries.

  20. Chemical and physical changes during seawater flow through intact dunite cores: An experimental study at 150-200 °C

    Science.gov (United States)

    Luhmann, Andrew J.; Tutolo, Benjamin M.; Bagley, Brian C.; Mildner, David F. R.; Scheuermann, Peter P.; Feinberg, Joshua M.; Ignatyev, Konstantin; Seyfried, William E.

    2017-10-01

    Two flow-through experiments were conducted to assess serpentinization of intact dunite cores. Permeability and fluid chemistry indicate significantly more reaction during the second experiment at 200 °C than the first experiment at 150 °C. Permeability decreased by a factor of 2.4 and 25 during the experiments at 150 and 200 °C, respectively. Furthermore, hydrogen and methane concentrations exceeded 600 μmol/kg and 300 μmol/kg during the 200 °C experiment, and were one and two orders of magnitude higher, respectively, than the 150 °C experiment. Fe K-edge X-ray absorption near edge structure analyses of alteration minerals demonstrated Fe oxidation that occurred during the 200 °C experiment. Vibrating sample magnetometer measurements on post-experimental cores indicated little to no magnetite production, suggesting that the hydrogen was largely generated by the oxidation of iron as olivine was converted to ferric iron (Fe(III)) serpentine and/or saponite. Scanning electron microscopy images suggested secondary mineralization on the post-experimental core from the 200 °C experiment, portraying the formation of a secondary phase with a honeycomb-like texture as well as calcite and wollastonite. Scanning electron microscopy images also illustrated dissolution along linear bands through the interiors of olivine crystals, possibly along pathways with abundant fluid inclusions. Energy dispersive X-ray spectroscopy identified Cl uptake in serpentine, while Fourier transform-infrared spectroscopy suggested the formation of serpentine, saponite, and talc. However, no change was observed when comparing pre- and post-experimental X-ray computed tomography scans of the cores. Furthermore, (ultra) small angle neutron scattering datasets were collected to assess changes in porosity, surface area, and fractal characteristics of the samples over the ≈ 1 nm- to 10 μm-scale range. The results from the 200 °C post-experimental core generally fell within the range of

  1. Experimental Study of gas-liquid two-phase flow affected by wall surface wettability

    International Nuclear Information System (INIS)

    Takamasa, T.; Hazuku, T.; Hibiki, T.

    2008-01-01

    To evaluate the effect of wall surface wettability on the characteristics of upward gas-liquid two-phase flow in a vertical pipe, an experimental study was performed using three test pipes: an acrylic pipe, a hydrophilic pipe and a hydrophobic pipe. Basic flow characteristics such as flow patterns, pressure drop and void fraction were measured in these three pipes. In the hydrophilic pipe, a slug to churn flow transition boundary was shifted to a higher gas velocity at a given liquid velocity, whereas a churn to annular flow transition boundary was shifted to a lower gas velocity at a given liquid velocity. In the hydrophobic pipe, an inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, while a droplet flow regime was observed in the region where an annular flow regime was observed in the acrylic pipe. At a high gas flow rate, the mean void fraction in the hydrophobic pipe was higher than in the acrylic pipe. The effect of surface wettability on frictional pressure loss was confirmed to be insignificant under the present experimental conditions

  2. Surface optimization and new cavitation model for lubricated flow

    Directory of Open Access Journals (Sweden)

    Dalissier Eric

    2013-12-01

    Full Text Available Le système piston/chemise/segment est le siège d’une partie importante des pertes en frottement du moteur (de l’ordre de 7% de l’énergie fournie par le moteur [1]. Une des pistes étudiées pour diminuer ces frottements consiste à introduire des rugosités à la surface de la chemise. Ces rugosités servent localement de réservoir au lubrifiant et permettent de limiter les contacts entre les segments et la chemise et donc de diminuer le frottement. Un des buts de notre travail était d’optimiser ces rugosités de surface en modélisant le système segment/chemise en présence de lubrifiant.

  3. Prediction of incipient flow boiling from a uniformly heated surface

    International Nuclear Information System (INIS)

    Yin, S.T.; Abdelmessih, A.H.

    1977-01-01

    This study was undertaken to investigate the phenomenon of liquid superheat during incipient boiling in a uniformly heated forced convection channel. Experimental data were obtained using Freon 11 as the test medium. Based on existing theories, an analytical method was developed for predicting the point of termination of nucleate boiling, observed during a decreasing heat flux process with a nucleation activated surface. The method may also be used to predict the point of boiling incipience, observed during an increasing heat flux process with a non-activated surface; this point does not appear to have been treated analytically in previous work. It can be shown that some of the existing models are special cases of the present formulation

  4. Fractal behaviour of flow of an inhomogeneous fluid over a smooth inclined surface

    International Nuclear Information System (INIS)

    Rouhani, S.; Maleki Jirsarani, N.; Ghane Motlagh, B.; Baradaran, S.; Shokrian, E.

    2001-01-01

    We have observed and analyzed fractal patterns made by the flow of an inhomogeneous fluid (a suspension) over an inclined smooth surface. We observed that if the angle of inclination is above a threshold (10 d eg C - 12 d eg C), the length of fractal clusters become infinity. We measured a fractal dimension of df=1.40 ± 0.05. This falls within the same general class of patterns of flow of water over an inhomogeneous surface. This observation is consistent with the results of theoretical modes for nonlinear fluid flow in random media

  5. Thermocouple Rakes for Measuring Boundary Layer Flows Extremely Close to Surface

    Science.gov (United States)

    Hwang, Danny P.; Fralick, Gustave C.; Martin, Lisa C.; Blaha, Charles A.

    2001-01-01

    Of vital interest to aerodynamic researchers is precise knowledge of the flow velocity profile next to the surface. This information is needed for turbulence model development and the calculation of viscous shear force. Though many instruments can determine the flow velocity profile near the surface, none of them can make measurements closer than approximately 0.01 in. from the surface. The thermocouple boundary-layer rake can measure much closer to the surface than conventional instruments can, such as a total pressure boundary layer rake, hot wire, or hot film. By embedding the sensors (thermocouples) in the region where the velocity is equivalent to the velocity ahead of a constant thickness strut, the boundary-layer flow profile can be obtained. The present device fabricated at the NASA Glenn Research Center microsystem clean room has a heater made of platinum and thermocouples made of platinum and gold. Equal numbers of thermocouples are placed both upstream and downstream of the heater, so that the voltage generated by each pair at the same distance from the surface is indicative of the difference in temperature between the upstream and downstream thermocouple locations. This voltage differential is a function of the flow velocity, and like the conventional total pressure rake, it can provide the velocity profile. In order to measure flow extremely close to the surface, the strut is made of fused quartz with extremely low heat conductivity. A large size thermocouple boundary layer rake is shown in the following photo. The latest medium size sensors already provide smooth velocity profiles well into the boundary layer, as close as 0.0025 in. from the surface. This is about 4 times closer to the surface than the previously used total pressure rakes. This device also has the advantage of providing the flow profile of separated flow and also it is possible to measure simultaneous turbulence levels within the boundary layer.

  6. Nuclear reactor core support incorporating also a cooling fluid flow system

    International Nuclear Information System (INIS)

    Pennell, W.E.

    1975-01-01

    A description is given of a core bearing plate with several modular intake units having cooling fluid intake openings on their lower extensions, and on their upper ends located above the bearing plate, at least one fuel assembly which is thus in communication with the area under the bearing plate through the modular intake unit. The means for introducing the cooling fluid into the reactor vessel area are located under the bearing plate. The lower ends of the modular intake have ribs arranged essentially on a plane and join together with openings provided between the seals, in such a manner that the ribs form a barrier. The cooling fluid intake openings are located above this barrier, so that the cooling fluid is compelled to cross it before penetrating into the modular intake units [fr

  7. Peeking Below the Snow Surface to Explore Amundsen Sea Climate Variability and Locate Optimal Ice-Core Sites

    Science.gov (United States)

    Neff, P. D.; Fudge, T. J.; Medley, B.

    2016-12-01

    Observations over recent decades reveal rapid changes in ice shelves and fast-flowing grounded ice along the Amundsen Sea coast of the West Antarctic Ice Sheet (WAIS). Long-term perspectives on this ongoing ice loss are needed to address a central question of Antarctic research: how much and how fast will Antarctic ice-loss raise sea level? Ice cores can provide insight into past variability of the atmospheric (wind) forcing of regional ocean dynamics affecting ice loss. Interannual variability of snow accumulation on coastal ice domes grounded near or within ice shelves reflects local to regional atmospheric circulation near the ice-ocean interface. Records of snow accumulation inferred from shallow ice cores strongly correlate with reanalysis precipitation and pressure fields, but ice cores have not yet been retrieved along the Amundsen Sea coast. High-frequency airborne radar data (NASA Operation IceBridge), however, have been collected over this region and we demonstrate that these data accurately reflect annual stratigraphy in shallow snow and firn (1 to 2 decades of accumulation). This further validates the agreement between radar snow accumulation records and climate reanalysis products. We then explore regional climate controls on local snow accumulation through comparison with gridded reanalysis products, providing a preview of what information longer coastal ice core records may provide with respect to past atmospheric forcing of ocean circulation and WAIS ice loss.

  8. Effects of surface roughness and electrokinetic heterogeneity on electroosmotic flow in microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Masilamani, Kannan; Ganguly, Suvankar; Feichtinger, Christian; Bartuschat, Dominik; Rüde, Ulrich, E-mail: suva_112@yahoo.co.in [Department of Computer Science 10 University of Erlangen-Nuremberg, Cauerstr.11 91058 Erlangen (Germany)

    2015-06-15

    In this paper, a hybrid lattice-Boltzmann and finite-difference (LB-FD) model is applied to simulate the effects of three-dimensional surface roughness and electrokinetic heterogeneity on electroosmotic flow (EOF) in a microchannel. The lattice-Boltzmann (LB) method has been employed to obtain the flow field and a finite-difference (FD) method is used to solve the Poisson-Boltzmann (PB) equation for the electrostatic potential distribution. Numerical simulation of flow through a square cross-section microchannel with designed roughness is conducted and the results are critically analysed. The effects of surface heterogeneity on the electroosmotic transport are investigated for different roughness height, width, roughness interval spacing, and roughness surface potential. Numerical simulations reveal that the presence of surface roughness changes the nature of electroosmotic transport through the microchannel. It is found that the electroosmotic velocity decreases with the increase in roughness height and the velocity profile becomes asymmetric. For the same height of the roughness elements, the EOF velocity rises with the increase in roughness width. For the heterogeneously charged rough channel, the velocity profile shows a distinct deviation from the conventional plug-like flow pattern. The simulation results also indicate locally induced flow vortices which can be utilized to enhance the flow and mixing within the microchannel. The present study has important implications towards electrokinetic flow control in the microchannel, and can provide an efficient way to design a microfluidic system of practical interest. (paper)

  9. High-resolution continuous-flow analysis setup for water isotopic measurement from ice cores using laser spectroscopy

    Science.gov (United States)

    Emanuelsson, B. D.; Baisden, W. T.; Bertler, N. A. N.; Keller, E. D.; Gkinis, V.

    2015-07-01

    Here we present an experimental setup for water stable isotope (δ18O and δD) continuous-flow measurements and provide metrics defining the performance of the setup during a major ice core measurement campaign (Roosevelt Island Climate Evolution; RICE). We also use the metrics to compare alternate systems. Our setup is the first continuous-flow laser spectroscopy system that is using off-axis integrated cavity output spectroscopy (OA-ICOS; analyzer manufactured by Los Gatos Research, LGR) in combination with an evaporation unit to continuously analyze water samples from an ice core. A Water Vapor Isotope Standard Source (WVISS) calibration unit, manufactured by LGR, was modified to (1) enable measurements on several water standards, (2) increase the temporal resolution by reducing the response time and (3) reduce the influence from memory effects. While this setup was designed for the continuous-flow analysis (CFA) of ice cores, it can also continuously analyze other liquid or vapor sources. The custom setups provide a shorter response time (~ 54 and 18 s for 2013 and 2014 setup, respectively) compared to the original WVISS unit (~ 62 s), which is an improvement in measurement resolution. Another improvement compared to the original WVISS is that the custom setups have a reduced memory effect. Stability tests comparing the custom and WVISS setups were performed and Allan deviations (σAllan) were calculated to determine precision at different averaging times. For the custom 2013 setup the precision after integration times of 103 s is 0.060 and 0.070 ‰ for δ18O and δD, respectively. The corresponding σAllan values for the custom 2014 setup are 0.030, 0.060 and 0.043 ‰ for δ18O, δD and δ17O, respectively. For the WVISS setup the precision is 0.035, 0.070 and 0.042 ‰ after 103 s for δ18O, δD and δ17O, respectively. Both the custom setups and WVISS setup are influenced by instrumental drift with δ18O being more drift sensitive than δD. The

  10. Phosphorus retention in surface-flow constructed wetlands targeting agricultural drainage water

    DEFF Research Database (Denmark)

    Dantas Mendes, Lipe Renato; Tonderski, Karin; Iversen, Bo Vangsø

    2018-01-01

    Surface-flow constructed wetlands (CWs) are potential cost-efficient solutions to mitigate phosphorus (P) loads from agricultural areas to surface waters. Hydraulic and phosphorus loading rates (HLR and PLR) are critical parameters that regulate P retention in these systems. The present study aim...

  11. Surface tension effects on vertical upward annular flows in a small diameter pipe

    Energy Technology Data Exchange (ETDEWEB)

    Sadatomi, Michio, E-mail: sadatomi@mech.kumamoto-u.ac.jp [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Kawahara, Akimaro [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Suzuki, Aruta [Plant Design & Engineering Dept., Environment, Energy & Plant Headquarters, Hitachi Zosen Corporation, 7-89, Nankokita 1-chome, Suminoe-ku, Osaka, 559-8559 (Japan)

    2016-12-15

    Highlights: • Surface tension effects were clarified on annular flow in a small diameter pipe. • The mean liquid film thickness became thinner with decreasing of surface tension. • The liquid droplet fraction and the interfacial shear stress became higher with it. • New prediction methods for the above parameters were developed and validated. - Abstract: Experiments were conducted to study the surface tension effects on vertical upward annular flows in a 5 mm I.D. pipe using water and low surface tension water with a little surfactant as the test liquid and air as the test gas. Firstly, the experimental results on the mean liquid film thickness, the liquid droplet fraction and the interfacial shear stress in annular flows together with some flow pictures are presented to clarify the surface tension effects. From these, the followings are clarified: In the low surface tension case, the liquid film surface becomes rough, the liquid film thickness thin, the liquid droplet fraction high, and the interfacial shear stress high. Secondary, correlations in literatures for the respective parameters are tested against the present data. The test results show that no correlation for the respective parameters could predict well the present data. Thus, correlations are revised by accounting for the surface tension effects. The results of the experiments, the correlations tests and their revisions mentioned above are presented in the present paper.

  12. Numerical simulation of cavitation flow characteristic on Pelton turbine bucket surface

    Science.gov (United States)

    Zeng, C. J.; Xiao, Y. X.; Zhu, W.; Yao, Y. Y.; Wang, Z. W.

    2015-01-01

    The internal flow in the rotating bucket of Pelton turbine is free water sheet flow with moving boundary. The runner operates under atmospheric and the cavitation in the bucket is still a controversial problem. While more and more field practice proved that there exists cavitation in the Pelton turbine bucket and the cavitation erosion may occur at the worst which will damage the bucket. So a well prediction about the cavitation flow on the bucket surface of Pelton turbine and the followed cavitation erosion characteristic can effectively guide the optimization of Pelton runner bucket and the stable operation of unit. This paper will investigate the appropriate numerical model and method for the unsteady 3D water-air-vapour multiphase cavitation flow which may occur on the Pelton bucket surface. The computational domain will include the nozzle pipe flow, semi-free surface jet and runner domain. Via comparing the numerical results of different turbulence, cavity and multiphase models, this paper will determine the suitable numerical model and method for the simulation of cavitation on the Pelton bucket surface. In order to investigate the conditions corresponding to the cavitation phenomena on the bucket surface, this paper will adopt the suitable model to simulate the various operational conditions of different water head and needle travel. Then, the characteristics of cavitation flow the development process of cavitation will be analysed in in great detail.

  13. Numerical simulation of cavitation flow characteristic on Pelton turbine bucket surface

    International Nuclear Information System (INIS)

    Zeng, C J; Xiao, Y X; Zhu, W; Yao, Y Y; Wang, Z W

    2015-01-01

    The internal flow in the rotating bucket of Pelton turbine is free water sheet flow with moving boundary. The runner operates under atmospheric and the cavitation in the bucket is still a controversial problem. While more and more field practice proved that there exists cavitation in the Pelton turbine bucket and the cavitation erosion may occur at the worst which will damage the bucket. So a well prediction about the cavitation flow on the bucket surface of Pelton turbine and the followed cavitation erosion characteristic can effectively guide the optimization of Pelton runner bucket and the stable operation of unit. This paper will investigate the appropriate numerical model and method for the unsteady 3D water-air-vapour multiphase cavitation flow which may occur on the Pelton bucket surface. The computational domain will include the nozzle pipe flow, semi-free surface jet and runner domain. Via comparing the numerical results of different turbulence, cavity and multiphase models, this paper will determine the suitable numerical model and method for the simulation of cavitation on the Pelton bucket surface. In order to investigate the conditions corresponding to the cavitation phenomena on the bucket surface, this paper will adopt the suitable model to simulate the various operational conditions of different water head and needle travel. Then, the characteristics of cavitation flow the development process of cavitation will be analysed in in great detail

  14. Numerical simulation of unsteady free surface flow and dynamic performance for a Pelton turbine

    International Nuclear Information System (INIS)

    Xiao, Y X; Wang, Z W; Yan, Z G; Cui, T

    2012-01-01

    Different from the reaction turbines, the hydraulic performance of the Pelton turbine is dynamic due to the unsteady free surface flow in the rotating buckets in time and space. This paper aims to present the results of investigations conducted on the free surface flow in a Pelton turbine rotating buckets. The unsteady numerical simulations were performed with the CFX code by using the Realizable k-ε turbulence model coupling the two-phase flow volume of fluid method. The unsteady free surface flow patterns and torque varying with the bucket rotating were analysed. The predicted relative performance at five operating conditions was compared with the field test results. The study was also conducted the interactions between the bucket rear and the water jet.

  15. Numerical simulation of unsteady free surface flow and dynamic performance for a Pelton turbine

    Science.gov (United States)

    Xiao, Y. X.; Cui, T.; Wang, Z. W.; Yan, Z. G.

    2012-11-01

    Different from the reaction turbines, the hydraulic performance of the Pelton turbine is dynamic due to the unsteady free surface flow in the rotating buckets in time and space. This paper aims to present the results of investigations conducted on the free surface flow in a Pelton turbine rotating buckets. The unsteady numerical simulations were performed with the CFX code by using the Realizable k-ε turbulence model coupling the two-phase flow volume of fluid method. The unsteady free surface flow patterns and torque varying with the bucket rotating were analysed. The predicted relative performance at five operating conditions was compared with the field test results. The study was also conducted the interactions between the bucket rear and the water jet.

  16. A study on the effects of heated surface wettability on nucleation characteristics in subcooled flow boiling

    International Nuclear Information System (INIS)

    Kajihara, Tomoyuki; Kaiho, Kazuhiro; Okawa, Tomio

    2014-01-01

    Subcooled flow boiling plays an important role in boiling water reactors because it influences the heat transfer performance from fuel rods, two-phase flow stabilities, and neutron moderation characteristics. In the present study, flow visualization of water subcooled flow boiling in a vertical heated channel was carried out to investigate the mechanisms of void fraction development. The two surfaces of distinctly different contact angles were used as the heated surface to investigate the effect of the surface wettability. It was observed that with an increase in the wall heat flux, more nucleation sites were activated and larger bubbles were produced at low-frequency. It was considered that formation of these large bubbles primarily contributed to the void fraction development. (author)

  17. 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.

  18. MHD Flow Towards a Permeable Surface with Prescribed Wall Heat Flux

    International Nuclear Information System (INIS)

    Ishak, Anuar; Nazar, Roslinda; Pop, Ioan

    2009-01-01

    The steady magnetohydrodynamic (MHD) mixed convection flow towards a vertical permeable surface with prescribed heat flux is investigated. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analysed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for the assisting flow, besides the solutions usually reported in the literature for the opposing fow

  19. Development of free surface flow between concentric cylinders with vertical axes

    International Nuclear Information System (INIS)

    Watanabe, T; Toya, Y; Nakamura, I

    2005-01-01

    Numerical and experimental studies are conducted on flows developing between two concentric cylinders with vertical axes. The inner cylinder rotates and the outer and the lower end wall are fixed. The upper boundary is a free surface. The flow is at rest in an initial state, and the inner cylinder impulsively begins to rotate or its rotation speed linearly increases to a prescribed value. The acceleration rate of the inner cylinder changes the formation processes of flows and/or the final flow modes. Time-dependent flows appear at higher Reynolds numbers, and the numerical and experimental results of the power spectra show some agreements. It is suggested that critical Reynolds numbers appear, at which the fluctuations in the displacement of the free surface and the kinetic energy of a velocity component steeply increase

  20. The exposure of bacteria to CdTe-core quantum dots: the importance of surface chemistry on cytotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Raphael [DCPR, Departement de Chimie Physique de Reactions, Nancy Universite, CNRS, 1 rue Grandville, BP 20451, F-54001 Nancy (France); Wolpert, Cecile; Guilloteau, Helene; Lambert, Jacques; Merlin, Christophe [LCPME, Laboratoire de Chimie Physique et Microbiologie pour l' Environnement, Nancy-Universite, CNRS, 405 rue de Vandoeuvre, F-54600 Villers-les-Nancy (France); Balan, Lavinia [DPG, Departement de Photochimie Generale, UMR CNRS 7525, Universite de Haute Alsace, ENSCMu, 3 rue Alfred Werner, F-68093 Mulhouse (France)], E-mail: Christophe.Merlin@pharma.uhp-nancy.fr

    2009-06-03

    A series of water-soluble CdTe-core quantum dots (QDs) with diameters below 5.0 nm and functionalized at their surface with polar ligands such as thioglycolic acid (TGA) or the tripeptide glutathione (GSH) were synthesized and characterized by UV-vis absorption spectroscopy, their photoluminescence measurements, atomic force microscopy (AFM) and transmission electron microscopy (TEM). Because cell elongations and growth inhibitions were observed during labeling experiments, the cytotoxicity of CdTe-core QDs was investigated. Using growth inhibition tests combining different bacterial strains with different CdTe-core QDs, it was possible to demonstrate that the cytotoxicity of QDs towards bacteria depends on exposure concentrations, surface chemistry and coating, and that it varied with the strain considered. Growth inhibition tests carried out with heavy-metal-resistant bacteria, as well as ICP-AES analyses of cadmium species released by CdTe-TGA QDs, demonstrated that the leakage of Cd{sup 2+} is not the main source of QD toxicity. Our study suggests that QD cytotoxicity is rather due to the formation of TeO{sub 2} and probably the existence of CdO formed by surface oxidation. In this respect, QDs possessing a CdO shell appeared very toxic.

  1. The effects of viscosity, surface tension, and flow rate on gasoil-water flow pattern in microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Boogar, Rahman Sadeghi; Gheshlaghi, Reza; Mahdavi, Mahmood Akhavan [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2013-01-15

    A microchannel was fabricated with glass tubes to investigate the effect of viscosity, surface tension, and flow rate on the liquid-liquid two-phase flow regime. Water and gasoil were selected as aqueous and organic working fluids, respectively. The two fluids were injected into the microchannel and created either slug or parallel profile depending on the applied conditions. The range of Reynolds and capillary numbers was chosen in such a way that neither inertia nor interfacial tension forces were negligible. Xanthan gum was used to increase viscosity and Triton X-100 (TX-100) and Sodium Dodecyl Sulfate (SDS) were used to reduce the interfacial tension. The results demonstrated that higher value of viscosity and flow rate increased interfacial area, but slug flow regime remained unchanged. The two surfactants showed different effects on the flow regime and interfacial area. Addition of TX-100 did not change the slug flow but decreased the interfacial area. In contrast, addition of SDS increased interfacial area by decreasing the slug’s length in the low concentrations and by switching from slug to parallel regime at high concentrations.

  2. Dust evolution, a global view: III. Core/mantle grains, organic nano-globules, comets and surface chemistry

    Science.gov (United States)

    2016-01-01

    Within the framework of The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), this work explores the surface processes and chemistry relating to core/mantle interstellar and cometary grain structures and their influence on the nature of these fascinating particles. It appears that a realistic consideration of the nature and chemical reactivity of interstellar grain surfaces could self-consistently and within a coherent framework explain: the anomalous oxygen depletion, the nature of the CO dark gas, the formation of ‘polar ice’ mantles, the red wing on the 3 μm water ice band, the basis for the O-rich chemistry observed in hot cores, the origin of organic nano-globules and the 3.2 μm ‘carbonyl’ absorption band observed in comet reflectance spectra. It is proposed that the reaction of gas phase species with carbonaceous a-C(:H) grain surfaces in the interstellar medium, in particular the incorporation of atomic oxygen into grain surfaces in epoxide functional groups, is the key to explaining these observations. Thus, the chemistry of cosmic dust is much more intimately related with that of the interstellar gas than has previously been considered. The current models for interstellar gas and dust chemistry will therefore most likely need to be fundamentally modified to include these new grain surface processes. PMID:28083090

  3. Passive control of flow structure interaction between a sphere and free-surface

    Directory of Open Access Journals (Sweden)

    Akilli Huseyin

    2012-04-01

    Full Text Available Flow characteristics for both a smooth and a vented sphere such as velocity vectors, patterns of streamlines, vorticity contours, stream-wise fluctuations, cross-stream velocity fluctuations and Reynolds stress correlations between a sphere and free-surface for various submerged ratio at Re =5,000 are studied by using dye visualization and the particle image velocimetry technique. Passive control of flow structure interaction between sphere and free surface was examined by using a modified geometry which has a 15% sphere diameter hole passing through the sphere equator. Both of the spheres were separately placed beneath the free surface with different positions from touching to the free surface to two sphere diameters below the free surface. It is demonstrated that reattachment point of the separated flow to the free surface varies for both of the sphere cases as the sphere position alters vertically through the water flow while the flow structure for the vented sphere occurs considerably symmetrical due to forming of a pair of counter-rotating ring vortices.

  4. 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.

  5. Initial adhesion of Listeria monocytogenes to solid surfaces under liquid flow

    DEFF Research Database (Denmark)

    Szlavik, Julie; Soares Paiva, Dionísio; Mørk, Nils

    2012-01-01

    .001) was observed but not of interactions between surface-shear stress. No correlation between surface hydrophobicity and IAR was observed. Addition of 5% NaCl during propagation resulted in a decrease in IAR whilst propagation in low nutrient media caused an increase indicating a general change in surface......Some strains of the food borne pathogen Listeria monocytogenes persist in food processing environments. The exact reason behind this phenomenon is not known, but strain differences in the ability to adhere to solid surfaces could offer an explanation. In the present work, initial adhesion of nine...... strains of L. monocytogenes was investigated under liquid flow at two levels of shear stress on six different surfaces using a flow chamber set-up with microscopy measurements. The surfaces tested were glass and PVC, and glass coated with beef extract, casein, and homogenised and unhomogenised milk...

  6. Shear flow generation and transport barrier formation on rational surface current sheets in tokamaks

    International Nuclear Information System (INIS)

    Wang Xiaogang; Xiao Chijie; Wang Jiaqi

    2009-01-01

    Full text: A thin current sheet with a magnetic field component in the same direction can form the electrical field perpendicularly pointing to the sheet, therefore an ExB flow with a strong shear across the current sheet. An electrical potential well is also found on the rational surface of RFP as well as the neutral sheet of the magnetotail with the E-field pointing to the rational (neutral) surface. Theoretically, a current singularity is found to be formed on the rational surface in ideal MHD. It is then very likely that the sheet current on the rational surfaces will generate the electrical potential well in its vicinity so the electrical field pointing to the sheet. It results in an ExB flow with a strong shear in the immediate neighborhood of the rational surface. It may be the cause of the transport barrier often seen near the low (m, n) rational surfaces with MHD signals. (author)

  7. [Studies on a sequential injection renewable surface reflectance spectrophotometric system using a microchip flow cell].

    Science.gov (United States)

    Wang, Jian-ya; Fang, Zhao-lun

    2002-02-01

    A microchip flow cell was developed for flow injection renewable surface assay by reflectance spectrophotometry. The flow cell was coupled to a sequential injection system and optical fiber photometric detection system. The flow cell featured a three-layer structure. The flow channel was cut into a silicone rubber membrance which formed the middle layer, and a porous filter was inlayed across a widened section of the channel to trap microbeads introduced into the flow cell. The area of the detection window of the flow cell was approximately 3.6 mm2, the volume of the bead trapped in the flow cell was 2.2 microL, the depth of the bead layer was 600 microns. A multistrand bifurcated optical fiber was coupled with incident light, detector and flow cell. The chromogenic reaction of Cr(VI) with 1,5-diphenylcarbohydrazide (DPC) which was adsorbed on trapped Polysorb C-18 beads was used as a model reaction to optimize the flow cell design and the experimental system. The reflectance of the renewable reaction surface was monitored at 540 nm. With 100 microL sample loaded and 1.0 mL.min-1 carrier flow rate, the linear response range was 0-0.6 microgram.mL-1 Cr(VI). A detection limit (3 sigma) of 6 ng.mL-1, precision of 1.5% RSD(n = 11), and a throughput of 64 samples per hour were achieved. Considerations in system and flow cell design, the influence of depth of the bead layer, weight of beads used, and the flow rates of carrier stream on the performance were discussed.

  8. Surface Tension Driven Instability in the Regime of Stokes Flow

    Science.gov (United States)

    Yao, Zhenwei; Bowick, Mark; Xing, Xiangjun

    2010-03-01

    A cylinder of liquid inside another liquid is unstable towards droplet formation. This instability is driven by minimization of surface tension energy and was analyzed first by [1,2] and then by [3]. We revisit this problem in the limit of small Laplace number, where the inertial of liquids can be completely ignored. The stream function is found to obey biharmonic equation, and its analytic solutions are found. We rederive Tomotika's main results, and also obtain many new analytic results about the velocity fields. We also apply our formalism to study the recent experiment on toroidal liquid droplet[4]. Our framework shall have many applications in micro-fluidics. [1] L.Rayleigh, On The Instability of A Cylinder of Viscous Liquid Under Capillary Force, Scientific Papers, Cambridge, Vol.III, 1902. [2] L.Rayleigh, On The Instability of Cylindrical Fluid Surfaces, Scientific Papers, Cambridge, Vol.III, 1902. [3] S.Tomotika, On the Instability of a Cylindrical Thread of a Viscous Liquid surround by Another Viscous Fluid, Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, Volume 150, Issue 870, pp. 322-337. [4] E.Pairam and A.Fern'andez-Nieves, Generation and Stability of Toroidal Droplets in a Viscous Liquid, Physical Review Letters 102, 234501 (2009).

  9. MHD biconvective flow of Powell Eyring nanofluid over stretched surface

    Science.gov (United States)

    Naseem, Faiza; Shafiq, Anum; Zhao, Lifeng; Naseem, Anum

    2017-06-01

    The present work is focused on behavioral characteristics of gyrotactic microorganisms to describe their role in heat and mass transfer in the presence of magnetohydrodynamic (MHD) forces in Powell-Eyring nanofluids. Implications concerning stretching sheet with respect to velocity, temperature, nanoparticle concentration and motile microorganism density were explored to highlight influential parameters. Aim of utilizing microorganisms was primarily to stabilize the nanoparticle suspension due to bioconvection generated by the combined effects of buoyancy forces and magnetic field. Influence of Newtonian heating was also analyzed by taking into account thermophoretic mechanism and Brownian motion effects to insinuate series solutions mediated by homotopy analysis method (HAM). Mathematical model captured the boundary layer regime that explicitly involved contemporary non linear partial differential equations converted into the ordinary differential equations. To depict nanofluid flow characteristics, pertinent parameters namely bioconvection Lewis number Lb, traditional Lewis number Le, bioconvection Péclet number Pe, buoyancy ratio parameter Nr, bioconvection Rayleigh number Rb, thermophoresis parameter Nt, Hartmann number M, Grashof number Gr, and Eckert number Ec were computed and analyzed. Results revealed evidence of hydromagnetic bioconvection for microorganism which was represented by graphs and tables. Our findings further show a significant effect of Newtonian heating over a stretching plate by examining the coefficient values of skin friction, local Nusselt number and the local density number. Comparison was made between Newtonian fluid and Powell-Eyring fluid on velocity field and temperature field. Results are compared of with contemporary studies and our findings are found in excellent agreement with these studies.

  10. Mixed convection boundary layer flow over a vertical surface embedded in a thermally stratified porous medium

    International Nuclear Information System (INIS)

    Ishak, Anuar; Nazar, Roslinda; Pop, Ioan

    2008-01-01

    The mixed convection boundary layer flow through a stable stratified porous medium bounded by a vertical surface is investigated. The external velocity and the surface temperature are assumed to vary as x m , where x is measured from the leading edge of the vertical surface and m is a constant. Numerical solutions for the governing Darcy and energy equations are obtained. The results indicate that the thermal stratification significantly affects the surface shear stress as well as the surface heat transfer, besides delays the boundary layer separation

  11. Special power supply and control system for the gas-cooled fast reactor-core flow test loop

    International Nuclear Information System (INIS)

    Hudson, T.L.

    1981-09-01

    The test bundle in the Gas-Cooled Fast Reactor-Core Flow Test Loop (GCFR-CFTL) requires a source of electrical power that can be controlled accurately and reliably over a wide range of steady-state and transient power levels and skewed power distributions to simulate GCFR operating conditions. Both ac and dc power systems were studied, and only those employing silicon-controlled rectifiers (SCRs) could meet the requirements. This report summarizes the studies, tests, evaluations, and development work leading to the selection. it also presents the design, procurement, testing, and evaluation of the first 500-kVa LMPL supply. The results show that the LMPL can control 60-Hz sine wave power from 200 W to 500 kVA

  12. Breakdown voltage at the electric terminals of GCFR-core flow test loop fuel rod simulators in helium and air

    International Nuclear Information System (INIS)

    Huntley, W.R.; Conley, T.B.

    1979-12-01

    Tests were performed to determine the ac and dc breakdown voltage at the terminal ends of a fuel rod simulator (FRS) in helium and air atmospheres. The tests were performed at low pressures (1 to 2 atm) and at temperatures from 20 to 350 0 C (68 to 660 0 F). The area of concern was the 0.64-mm (0.025-in.) gap between the coaxial conductor of the FRS and the sheaths of the four internal thermocouples as they exit the FRS. The tests were prformed to ensure a sufficient safety margin during Core Flow Test Loop (CFTL) operations that require potentials up to 350 V ac at the FRS terminals. The primary conclusion from the test results is that the CFTL cannot be operated safely if the terminal ends of the FRSs are surrounded by a helium atmosphere but can be operated safely in air

  13. Navier-Stokes Computations With One-Equation Turbulence Model for Flows Along Concave Wall Surfaces

    Science.gov (United States)

    Wang, Chi R.

    2005-01-01

    This report presents the use of a time-marching three-dimensional compressible Navier-Stokes equation numerical solver with a one-equation turbulence model to simulate the flow fields developed along concave wall surfaces without and with a downstream extension flat wall surface. The 3-D Navier- Stokes numerical solver came from the NASA Glenn-HT code. The one-equation turbulence model was derived from the Spalart and Allmaras model. The computational approach was first calibrated with the computations of the velocity and Reynolds shear stress profiles of a steady flat plate boundary layer flow. The computational approach was then used to simulate developing boundary layer flows along concave wall surfaces without and with a downstream extension wall. The author investigated the computational results of surface friction factors, near surface velocity components, near wall temperatures, and a turbulent shear stress component in terms of turbulence modeling, computational mesh configurations, inlet turbulence level, and time iteration step. The computational results were compared with existing measurements of skin friction factors, velocity components, and shear stresses of the developing boundary layer flows. With a fine computational mesh and a one-equation model, the computational approach could predict accurately the skin friction factors, near surface velocity and temperature, and shear stress within the flows. The computed velocity components and shear stresses also showed the vortices effect on the velocity variations over a concave wall. The computed eddy viscosities at the near wall locations were also compared with the results from a two equation turbulence modeling technique. The inlet turbulence length scale was found to have little effect on the eddy viscosities at locations near the concave wall surface. The eddy viscosities, from the one-equation and two-equation modeling, were comparable at most stream-wise stations. The present one

  14. Assessment of Two-Phase Flow Heat Transfer Correlations for Molten Core-Concrete Interaction Study

    International Nuclear Information System (INIS)

    Tourniaire, B.; Varo, O.

    2006-01-01

    The prediction of heat transfer between corium pool and concrete basemat is of particular significance in the framework of the study of PWR's severe accident. Heat transfer directly governs the ablation velocity of concrete in case of molten core-concrete interaction (MCCI) and, consequently, the time delay when the reactor cavity may fail. From a restricted hydrodynamic point of view, this issue is related to heat transfer between a heated bubbling pool and a porous wall with gas injection. Several experimental studies have been performed with simulant materials and many correlations have been provided to address this issue. The main purpose of this paper is to assess these correlations from comparisons against the available experimental data. After a review of these data, the different correlations are presented. Attention focuses here on the correlations generally used in MCCI study: Kutateladze-Malenkov, Konsetov and BALI correlations. The Deckwer's correlation is also included in this review. The comparisons between the results of these correlations and the experimental data are then discussed. (authors)

  15. The role of zonal flows and predator-prey oscillations in triggering the formation of edge and core transport barriers

    Science.gov (United States)

    Schmitz, L.; Zeng, L.; Rhodes, T. L.; Hillesheim, J. C.; Peebles, W. A.; Groebner, R. J.; Burrell, K. H.; McKee, G. R.; Yan, Z.; Tynan, G. R.; Diamond, P. H.; Boedo, J. A.; Doyle, E. J.; Grierson, B. A.; Chrystal, C.; Austin, M. E.; Solomon, W. M.; Wang, G.

    2014-07-01

    We present direct evidence of low frequency, radially sheared, turbulence-driven flows (zonal flows (ZFs)) triggering edge transport barrier formation preceding the L- to H-mode transition via periodic turbulence suppression in limit-cycle oscillations (LCOs), consistent with predator-prey dynamics. The final transition to edge-localized mode-free H-mode occurs after the equilibrium E × B flow shear increases due to ion pressure profile evolution. ZFs are also observed to initiate formation of an electron internal transport barrier (ITB) at the q = 2 rational surface via local suppression of electron-scale turbulence. Multi-channel Doppler backscattering (DBS) has revealed the radial structure of the ZF-induced shear layer and the E × B shearing rate, ωE×B, in both barrier types. During edge barrier formation, the shearing rate lags the turbulence envelope during the LCO by 90°, transitioning to anti-correlation (180°) when the equilibrium shear dominates the turbulence-driven flow shear due to the increasing edge pressure gradient. The time-dependent flow shear and the turbulence envelope are anti-correlated (180° out of phase) in the electron ITB. LCOs with time-reversed evolution dynamics (transitioning from an equilibrium-flow dominated to a ZF-dominated state) have also been observed during the H-L back-transition and are potentially of interest for controlled ramp-down of the plasma stored energy and pressure (normalized to the poloidal magnetic field) \\beta_{\\theta} =2\\mu_{0} n{( {T_{e} +T_{i}})}/{B_{\\theta}^{2}} in ITER.

  16. Three-dimensional rotational plasma flows near solid surfaces in an axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Gorshunov, N. M., E-mail: gorshunov-nm@nrcki.ru; Potanin, E. P., E-mail: potanin45@yandex.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-11-15

    A rotational flow of a conducting viscous medium near an extended dielectric disk in a uniform axial magnetic field is analyzed in the magnetohydrodynamic (MHD) approach. An analytical solution to the system of nonlinear differential MHD equations of motion in the boundary layer for the general case of different rotation velocities of the disk and medium is obtained using a modified Slezkin–Targ method. A particular case of a medium rotating near a stationary disk imitating the end surface of a laboratory device is considered. The characteristics of a hydrodynamic flow near the disk surface are calculated within the model of a finite-thickness boundary layer. The influence of the magnetic field on the intensity of the secondary flow is studied. Calculations are performed for a weakly ionized dense plasma flow without allowance for the Hall effect and plasma compressibility. An MHD flow in a rotating cylinder bounded from above by a retarding cap is considered. The results obtained can be used to estimate the influence of the end surfaces on the main azimuthal flow, as well as the intensities of circulating flows in various devices with rotating plasmas, in particular, in plasma centrifuges and laboratory devices designed to study instabilities of rotating plasmas.

  17. Preparation of Multifunctional Fe@Au Core-Shell Nanoparticles with Surface Grafting as a Potential Treatment for Magnetic Hyperthermia

    Directory of Open Access Journals (Sweden)

    Ren-Jei Chung

    2014-01-01

    Full Text Available Iron core gold shell nanoparticles grafted with Methotrexate (MTX and indocyanine green (ICG were synthesized for the first time in this study, and preliminarily evaluated for their potential in magnetic hyperthermia treatment. The core-shell Fe@Au nanoparticles were prepared via the microemulsion process and then grafted with MTX and ICG using hydrolyzed poly(styrene-alt-maleic acid (PSMA to obtain core-shell Fe@Au-PSMA-ICG/MTX nanoparticles. MTX is an anti-cancer therapeutic, and ICG is a fluorescent dye. XRD, TEM, FTIR and UV-Vis spectrometry were performed to characterize the nanoparticles. The data indicated that the average size of the nanoparticles was 6.4 ± 09 nm and that the Au coating protected the Fe core from oxidation. MTX and ICG were successfully grafted onto the surface of the nanoparticles. Under exposure to high frequency induction waves, the superparamagnetic nanoparticles elevated the temperature of a solution in a few minutes, which suggested the potential for an application in magnetic hyperthermia treatment. The in vitro studies verified that the nanoparticles were biocompatible; nonetheless, the Fe@Au-PSMA-ICG/MTX nanoparticles killed cancer cells (Hep-G2 via the magnetic hyperthermia mechanism and the release of MTX.

  18. Preparation of Multifunctional Fe@Au Core-Shell Nanoparticles with Surface Grafting as a Potential Treatment for Magnetic Hyperthermia.

    Science.gov (United States)

    Chung, Ren-Jei; Shih, Hui-Ting

    2014-01-24

    Iron core gold shell nanoparticles grafted with Methotrexate (MTX) and indocyanine green (ICG) were synthesized for the first time in this study, and preliminarily evaluated for their potential in magnetic hyperthermia treatment. The core-shell Fe@Au nanoparticles were prepared via the microemulsion process and then grafted with MTX and ICG using hydrolyzed poly(styrene-alt-maleic acid) (PSMA) to obtain core-shell Fe@Au-PSMA-ICG/MTX nanoparticles. MTX is an anti-cancer therapeutic, and ICG is a fluorescent dye. XRD, TEM, FTIR and UV-Vis spectrometry were performed to characterize the nanoparticles. The data indicated that the average size of the nanoparticles was 6.4 ± 09 nm and that the Au coating protected the Fe core from oxidation. MTX and ICG were successfully grafted onto the surface of the nanoparticles. Under exposure to high frequency induction waves, the superparamagnetic nanoparticles elevated the temperature of a solution in a few minutes, which suggested the potential for an application in magnetic hyperthermia treatment. The in vitro studies verified that the nanoparticles were biocompatible; nonetheless, the Fe@Au-PSMA-ICG/MTX nanoparticles killed cancer cells (Hep-G2) via the magnetic hyperthermia mechanism and the release of MTX.

  19. Retention/Diffusivity Studies in Free-Surface Flowing Liquid Lithium

    International Nuclear Information System (INIS)

    R.A. Stubbers; G.H. Miley; M. Nieto; W. Olczak; D.N. Ruzic; A. Hassanein

    2004-01-01

    FLIRE was designed to measure the hydrogen and helium retention and diffusivity in a flowing stream of liquid lithium, and it has accomplished these goals. Retention coefficients for helium in the flowing liquid stream were 0.1-2% for flow speeds of 44 cm/s and implantation energies between 500 and 2000 eV. The energy dependence of retention is linear for the energy range considered, as expected, and the dependence of retention on flow velocity fits the expected square-root of flow speed dependence. Estimates of the helium diffusion coefficient in the flowing lithium stream were ∼ 4 x 10 -7 cm 2 /s, and are independent of implantation energy. This value is much lower than expected, which could be due to several factors, such as mixing, bubble formation or surface film formation. In the case of hydrogen, long term retention and release mechanisms are of greatest importance, since this relates to tritium inventory in flowing lithium PFCs for fusion applications. The amount of hydride formation was measured for flowing lithium exposed to neutral deuterium gas. Thermal desorption spectroscopy (TDS) measurements indicate that the hydride concentration was between 0.1 and 0.2% over a wide range of pressures (6.5 x 10 -5 to 1 Torr). This result implies that the deuterium absorption rate is limited by the surface dissociation rate, since deuterium (hydrogen/tritium) is absorbed in its atomic form, not its molecular form

  20. Retention/Diffusivity Studies in Free-Surface Flowing Liquid Lithium

    Energy Technology Data Exchange (ETDEWEB)

    R.A. Stubbers; G.H. Miley; M. Nieto; W. Olczak; D.N. Ruzic; A. Hassanein

    2004-12-14

    FLIRE was designed to measure the hydrogen and helium retention and diffusivity in a flowing stream of liquid lithium, and it has accomplished these goals. Retention coefficients for helium in the flowing liquid stream were 0.1-2% for flow speeds of 44 cm/s and implantation energies between 500 and 2000 eV. The energy dependence of retention is linear for the energy range considered, as expected, and the dependence of retention on flow velocity fits the expected square-root of flow speed dependence. Estimates of the helium diffusion coefficient in the flowing lithium stream were {approx} 4 x 10{sup -7} cm{sup 2}/s, and are independent of implantation energy. This value is much lower than expected, which could be due to several factors, such as mixing, bubble formation or surface film formation. In the case of hydrogen, long term retention and release mechanisms are of greatest importance, since this relates to tritium inventory in flowing lithium PFCs for fusion applications. The amount of hydride formation was measured for flowing lithium exposed to neutral deuterium gas. Thermal desorption spectroscopy (TDS) measurements indicate that the hydride concentration was between 0.1 and 0.2% over a wide range of pressures (6.5 x 10{sup -5} to 1 Torr). This result implies that the deuterium absorption rate is limited by the surface dissociation rate, since deuterium (hydrogen/tritium) is absorbed in its atomic form, not its molecular form.

  1. Stability of surface plastic flow in large strain deformation of metals

    Science.gov (United States)

    Viswanathan, Koushik; Udapa, Anirduh; Sagapuram, Dinakar; Mann, James; Chandrasekar, Srinivasan

    We examine large-strain unconstrained simple shear deformation in metals using a model two-dimensional cutting system and high-speed in situ imaging. The nature of the deformation mode is shown to be a function of the initial microstructure state of the metal and the deformation geometry. For annealed metals, which exhibit large ductility and strain hardening capacity, the commonly assumed laminar flow mode is inherently unstable. Instead, the imposed shear is accommodated by a highly rotational flow-sinuous flow-with vortex-like components and large-amplitude folding on the mesoscale. Sinuous flow is triggered by a plastic instability on the material surface ahead of the primary region of shear. On the other hand, when the material is extensively strain-hardened prior to shear, laminar flow again becomes unstable giving way to shear banding. The existence of these flow modes is established by stability analysis of laminar flow. The role of the initial microstructure state in determining the change in stability from laminar to sinuous / shear-banded flows in metals is elucidated. The implications for cutting, forming and wear processes for metals, and to surface plasticity phenomena such as mechanochemical Rehbinder effects are discussed.

  2. Numerical and experimental investigation of the 3D free surface flow in a model Pelton turbine

    International Nuclear Information System (INIS)

    Fiereder, R; Riemann, S; Schilling, R

    2010-01-01

    This investigation focuses on the numerical and experimental analysis of the 3D free surface flow in a Pelton turbine. In particular, two typical flow conditions occurring in a full scale Pelton turbine - a configuration with a straight inlet as well as a configuration with a 90 degree elbow upstream of the nozzle - are considered. Thereby, the effect of secondary flow due to the 90 degree bending of the upstream pipe on the characteristics of the jet is explored. The hybrid flow field consists of pure liquid flow within the conduit and free surface two component flow of the liquid jet emerging out of the nozzle into air. The numerical results are validated against experimental investigations performed in the laboratory of the Institute of Fluid Mechanics (FLM). For the numerical simulation of the flow the in-house unstructured fully parallelized finite volume solver solver3D is utilized. An advanced interface capturing model based on the classic Volume of Fluid method is applied. In order to ensure sharp interface resolution an additional convection term is added to the transport equation of the volume fraction. A collocated variable arrangement is used and the set of non-linear equations, containing fluid conservation equations and model equations for turbulence and volume fraction, are solved in a segregated manner. For pressure-velocity coupling the SIMPLE and PISO algorithms are implemented. Detailed analysis of the observed flow patterns in the jet and of the jet geometry are presented.

  3. Numerical and experimental investigation of the 3D free surface flow in a model Pelton turbine

    Energy Technology Data Exchange (ETDEWEB)

    Fiereder, R; Riemann, S; Schilling, R, E-mail: fiereder@lhm.mw.tum.d [Department of Fluid Mechanics, Technische Universitaet Muenchen Bolzmannstrasse 15, Garching, 85748 (Germany)

    2010-08-15

    This investigation focuses on the numerical and experimental analysis of the 3D free surface flow in a Pelton turbine. In particular, two typical flow conditions occurring in a full scale Pelton turbine - a configuration with a straight inlet as well as a configuration with a 90 degree elbow upstream of the nozzle - are considered. Thereby, the effect of secondary flow due to the 90 degree bending of the upstream pipe on the characteristics of the jet is explored. The hybrid flow field consists of pure liquid flow within the conduit and free surface two component flow of the liquid jet emerging out of the nozzle into air. The numerical results are validated against experimental investigations performed in the laboratory of the Institute of Fluid Mechanics (FLM). For the numerical simulation of the flow the in-house unstructured fully parallelized finite volume solver solver3D is utilized. An advanced interface capturing model based on the classic Volume of Fluid method is applied. In order to ensure sharp interface resolution an additional convection term is added to the transport equation of the volume fraction. A collocated variable arrangement is used and the set of non-linear equations, containing fluid conservation equations and model equations for turbulence and volume fraction, are solved in a segregated manner. For pressure-velocity coupling the SIMPLE and PISO algorithms are implemented. Detailed analysis of the observed flow patterns in the jet and of the jet geometry are presented.

  4. Numerical and experimental investigation of the 3D free surface flow in a model Pelton turbine

    Science.gov (United States)

    Fiereder, R.; Riemann, S.; Schilling, R.

    2010-08-01

    This investigation focuses on the numerical and experimental analysis of the 3D free surface flow in a Pelton turbine. In particular, two typical flow conditions occurring in a full scale Pelton turbine - a configuration with a straight inlet as well as a configuration with a 90 degree elbow upstream of the nozzle - are considered. Thereby, the effect of secondary flow due to the 90 degree bending of the upstream pipe on the characteristics of the jet is explored. The hybrid flow field consists of pure liquid flow within the conduit and free surface two component flow of the liquid jet emerging out of the nozzle into air. The numerical results are validated against experimental investigations performed in the laboratory of the Institute of Fluid Mechanics (FLM). For the numerical simulation of the flow the in-house unstructured fully parallelized finite volume solver solver3D is utilized. An advanced interface capturing model based on the classic Volume of Fluid method is applied. In order to ensure sharp interface resolution an additional convection term is added to the transport equation of the volume fraction. A collocated variable arrangement is used and the set of non-linear equations, containing fluid conservation equations and model equations for turbulence and volume fraction, are solved in a segregated manner. For pressure-velocity coupling the SIMPLE and PISO algorithms are implemented. Detailed analysis of the observed flow patterns in the jet and of the jet geometry are presented.

  5. Trichodesmium blooms and warm-core ocean surface features in the Arabian Sea and the Bay of Bengal.

    Science.gov (United States)

    Jyothibabu, R; Karnan, C; Jagadeesan, L; Arunpandi, N; Pandiarajan, R S; Muraleedharan, K R; Balachandran, K K

    2017-08-15

    Trichodesmium is a bloom-forming, diazotrophic, non-heterocystous cyanobacteria widely distributed in the warmer oceans, and their bloom is considered a 'biological indication' of stratification and nitrogen limitation in the ocean surface layer. In the first part of this paper, based on the retrospective analyses of the ocean surface mesoscale features associated with 59 Trichodesmium bloom incidences recorded in the past, 32 from the Arabian Sea and the Bay of Bengal, and 27 from the rest of the world, we have showed that warm-core features have an inducing effect on bloom formation. In the second part, we have considered the environmental preferences of Trichodesmium bloom based on laboratory and field studies across the globe, and proposed a view about how warm-core features could provide an inducing pre-requisite condition for the bloom formation in the Arabian Sea and the Bay of Bengal. Proposed that the subsurface waters of warm-core features maintain more likely chances for the conducive nutrient and light conditions required for the triggering of the blooms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Comprehensive study of flow and heat transfer at the surface of circular cooling fin

    Science.gov (United States)

    Mityakov, V. Yu; Grekov, M. A.; Gusakov, A. A.; Sapozhnikov, S. Z.; Seroshtanov, V. V.; Bashkatov, A. V.; Dymkin, A. N.; Pavlov, A. V.; Milto, O. A.; Kalmykov, K. S.

    2017-11-01

    For the first time is proposed to combine heat flux measurements with thermal imaging and PIV (particle image velocimetry) for a comprehensive study of flow and heat transfer at the surface of the circular cooling fin. The investigated hollow fin is heated from within with saturated water steam; meanwhile the isothermal external surface simulates one of the perfect fin. Flow and heat transfer at the surface of the solid fin of the same size and shape, made of titanium alloy is investigated in the same regimes. Gradient Heat Flux Sensors (GHFS) were installed at different places of the fin surface. Velocity field around a cylinder, temperature field at the surface of the fin and heat flux for each rated time were obtained. Comprehensive method including heat flux measurement, PIV and thermal imaging allow to study flow and heat transfer at the surface of the fin in real time regime. The possibility to study flow and heat transfer for non-isothermal fins is shown; it is allow to improve traditional calculation of the cooling fins.

  7. A wind tunnel study of flows over idealised urban surfaces with roughness sublayer corrections

    Science.gov (United States)

    Ho, Yat-Kiu; Liu, Chun-Ho

    2017-10-01

    Dynamics in the roughness (RSLs) and inertial (ISLs) sublayers in the turbulent boundary layers (TBLs) over idealised urban surfaces are investigated analytically and experimentally. In this paper, we derive an analytical solution to the mean velocity profile, which is a continuous function applicable to both RSL and ISL, over rough surfaces in isothermal conditions. Afterwards, a modified mixing-length model for RSL/ISL transport is developed that elucidates how surface roughness affects the turbulence motions. A series of wind tunnel experiments are conducted to measure the vertical profiles of mean and fluctuating velocities, together with momentum flux over various configurations of surface-mounted ribs in cross flows using hot-wire anemometry (HWA). The analytical solution agrees well with the wind tunnel result that improves the estimate to mean velocity profile over urban surfaces and TBL dynamics as well. The thicknesses of RSL and ISL are calculated by monitoring the convergence/divergence between the temporally averaged and spatio-temporally averaged profiles of momentum flux. It is found that the height of RSL/ISL interface is a function of surface roughness. Examining the direct, physical influence of roughness elements on near-surface RSL flows reveals that the TBL flows over rough surfaces exhibit turbulence motions of two different length scales which are functions of the RSL and ISL structure. Conclusively, given a TBL, the rougher the surface, the higher is the RSL intruding upward that would thinner the ISL up to 50 %. Therefore, the conventional ISL log-law approximation to TBL flows over urban surfaces should be applied with caution.

  8. INVESTIGATION ON THERMAL-FLOW CHARACTERISTICS OF HTGR CORE USING THERMIX-KONVEK MODULE AND VSOP'94 CODE

    Directory of Open Access Journals (Sweden)

    Sudarmono Sudarmono

    2015-03-01

    Full Text Available The failure of heat removal system of water-cooled reactor such as PWR in Three Mile Islands and Fukushima Daiichi BWR makes nuclear society starting to consider the use of high temperature gas-cooled reactor (HTGR. Reactor Physics and Technology Division – Center for Nuclear Reactor Safety and Technology  (PTRKN has tasks to perform research and development on the conceptual design of cogeneration gas cooled reactor with medium power level of 200 MWt. HTGR is one of nuclear energy generation system, which has high energy efficiency, and has high and clean inherent safety level. The geometry and structure of the HTGR200 core are designed to produce the output of helium gas coolant temperature as high as 950 °C to be used for hydrogen production and other industrial processes in co-generative way. The output of very high temperature helium gas will cause thermal stress on the fuel pebble that threats the integrity of fission product confinement. Therefore, it is necessary to perform thermal-flow evaluation to determine the temperature distribution in the graphite and fuel pebble in the HTGR core. The evaluation was carried out by Thermix-Konvek module code that has been already integrated into VSOP'94 code. The HTGR core geometry was done using BIRGIT module code for 2-D model (RZ model with 5 channels of pebble flow in active core in the radial direction. The evaluation results showed that the highest and lowest temperatures in the reactor core are 999.3 °C and 886.5 °C, while the highest temperature of TRISO UO2 is 1510.20 °C in the position (z= 335.51 cm; r=0 cm. The analysis done based on reactor condition of 120 kg/s of coolant mass flow rate, 7 MPa of pressure and 200 MWth of power. Compared to the temperature distribution resulted between VSOP’94 code and fuel temperature limitation as high as 1600 oC, there is enough safety margin from melting or disintegrating. Keywords: Thermal-Flow, VSOP’94, Thermix-Konvek, HTGR, temperature

  9. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina

    2014-04-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  10. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina; Bourlinos, Athanasios B.; Kozak, Ondrej; Berka, Karel; Siskova, Karolina M.; Havrdova, Marketa; Tucek, Jiri; Safarova, Klara; Otyepka, Michal; Giannelis, Emmanuel P.; Zboril, Radek

    2014-01-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  11. Surface, core, and structure modifications of phosphorus-containing dendrimers. Influence on the thermal stability

    OpenAIRE

    Turrin , Cédric-Olivier; Maraval , Valérie; Leclaire , Julien; Dantras , Eric; Lacabanne , Colette; Caminade , Anne-Marie; Majoral , Jean-Pierre

    2003-01-01

    International audience; Three new series of phosphorus-containing dendrimers are described. Their solubility depends on the type of end groups they bear. Perfluoroalkyl chains give dendrimers soluble in chlorofluorocarbons, whereas guanidinium and pyridinium derivatives give watersoluble compounds. The thermal stability of these compounds, as well as of 19 other dendrimers of various generations, having various cores, or various end groups, or branching points is studied. The main feature of ...

  12. Magnetohydrodynamic viscous flow over a nonlinearly moving surface: Closed-form solutions

    Science.gov (United States)

    Fang, Tiegang

    2014-05-01

    In this paper, the magnetohydrodynamic (MHD) flow over a nonlinearly (power-law velocity) moving surface is investigated analytically and solutions are presented for a few special conditions. The solutions are obtained in closed forms with hyperbolic functions. The effects of the magnetic, the wall moving, and the mass transpiration parameters are discussed. These solutions are important to show the flow physics as well as to be used as bench mark problems for numerical validation and development of new solution schemes.

  13. Effect of texture randomization on the slip and interfacial robustness in turbulent flows over superhydrophobic surfaces

    Science.gov (United States)

    Seo, Jongmin; Mani, Ali

    2018-04-01

    Superhydrophobic surfaces demonstrate promising potential for skin friction reduction in naval and hydrodynamic applications. Recent developments of superhydrophobic surfaces aiming for scalable applications use random distribution of roughness, such as spray coating and etched process. However, most previous analyses of the interaction between flows and superhydrophobic surfaces studied periodic geometries that are economically feasible only in laboratory-scale experiments. In order to assess the drag reduction effectiveness as well as interfacial robustness of superhydrophobic surfaces with randomly distributed textures, we conduct direct numerical simulations of turbulent flows over randomly patterned interfaces considering a range of texture widths w+≈4 -26 , and solid fractions ϕs=11 %-25 % . Slip and no-slip boundary conditions are implemented in a pattern, modeling the presence of gas-liquid interfaces and solid elements. Our results indicate that slip of randomly distributed textures under turbulent flows is about 30 % less than those of surfaces with aligned features of the same size. In the small texture size limit w+≈4 , the slip length of the randomly distributed textures in turbulent flows is well described by a previously introduced Stokes flow solution of randomly distributed shear-free holes. By comparing DNS results for patterned slip and no-slip boundary against the corresponding homogenized slip length boundary conditions, we show that turbulent flows over randomly distributed posts can be represented by an isotropic slip length in streamwise and spanwise direction. The average pressure fluctuation on a gas pocket is similar to that of the aligned features with the same texture size and gas fraction, but the maximum interface deformation at the leading edge of the roughness element is about twice as large when the textures are randomly distributed. The presented analyses provide insights on implications of texture randomness on drag

  14. Solutal Marangoni flows of miscible liquids drive transport without surface contamination

    Science.gov (United States)

    Kim, Hyoungsoo; Muller, Koen; Shardt, Orest; Afkhami, Shahriar; Stone, Howard A.

    2017-11-01

    Mixing and spreading of different liquids are omnipresent in nature, life and technology, such as oil pollution on the sea, estuaries, food processing, cosmetic and beverage industries, lab-on-a-chip devices, and polymer processing. However, the mixing and spreading mechanisms for miscible liquids remain poorly characterized. Here, we show that a fully soluble liquid drop deposited on a liquid surface remains as a static lens without immediately spreading and mixing, and simultaneously a Marangoni-driven convective flow is generated, which are counterintuitive results when two liquids have different surface tensions. To understand the dynamics, we develop a theoretical model to predict the finite spreading time and length scales, the Marangoni-driven convection flow speed, and the finite timescale to establish the quasi-steady state for the Marangoni flow. The fundamental understanding of this solutal Marangoni flow may enable driving bulk flows and constructing an effective drug delivery and surface cleaning approach without causing surface contamination by immiscible chemical species.

  15. Effects of flow on corrosion and surface film formation on an alkali borosilicate glass

    International Nuclear Information System (INIS)

    Clark, D.E.; Christensen, H.; Hermansson, H.P.; Sundvall, S.B.; Werme, L.

    1984-01-01

    Samples of the Swedish KBS glass type ABS 39 have been leached in doubly distilled water for 28 days at 90 0 C under static and flow conditions. After leaching, pH, weight loss, and elemental mass loss were determined. Surface film formation was studied by using IRRS, SEM-EDS, and SIMS analyses. Increasing the flow rate resulted in a decreased attack on the glass surface. Na and B were depleted while Al, Fe, La, and U were enriched at the surfaces of all the samples. The depth of the extensively leached layer determined by SIMS was approximately 6 μm on the low-flow-rate sample and about 2 μm on the high-flow-rate sample. SEM analysis also showed some variations in the thickness of the leached layers, but in general, the thickness of the layer on the 0.5 mL/h samples was about 3 times greater than on the 90 mL/g samples. Small particles ( 2 for the static and 0.5 mL/h samples and 6 g/m 2 for the 90 mL/h samples. This factor of 3 difference in weight loss between the low and high flow rates correlates well with the factor of 3 difference in their leached depths. A model is proposed to explain the results based on the effectiveness of protective surface layers

  16. Surface representations of two- and three-dimensional fluid flow topology

    Science.gov (United States)

    Helman, James L.; Hesselink, Lambertus

    1990-01-01

    We discuss our work using critical point analysis to generate representations of the vector field topology of numerical flow data sets. Critical points are located and characterized in a two-dimensional domain, which may be either a two-dimensional flow field or the tangential velocity field near a three-dimensional body. Tangent curves are then integrated out along the principal directions of certain classes of critical points. The points and curves are linked to form a skeleton representing the two-dimensional vector field topology. When generated from the tangential velocity field near a body in a three-dimensional flow, the skeleton includes the critical points and curves which provide a basis for analyzing the three-dimensional structure of the flow separation. The points along the separation curves in the skeleton are used to start tangent curve integrations to generate surfaces representing the topology of the associated flow separations.

  17. Nanoscale surface modifications to control capillary flow characteristics in PMMA microfluidic devices

    Directory of Open Access Journals (Sweden)

    Mukhopadhyay Subhadeep

    2011-01-01

    Full Text Available Abstract Polymethylmethacrylate (PMMA microfluidic devices have been fabricated using a hot embossing technique to incorporate micro-pillar features on the bottom wall of the device which when combined with either a plasma treatment or the coating of a diamond-like carbon (DLC film presents a range of surface modification profiles. Experimental results presented in detail the surface modifications in the form of distinct changes in the static water contact angle across a range from 44.3 to 81.2 when compared to pristine PMMA surfaces. Additionally, capillary flow of water (dyed to aid visualization through the microfluidic devices was recorded and analyzed to provide comparison data between filling time of a microfluidic chamber and surface modification characteristics, including the effects of surface energy and surface roughness on the microfluidic flow. We have experimentally demonstrated that fluid flow and thus filling time for the microfluidic device was significantly faster for the device with surface modifications that resulted in a lower static contact angle, and also that the incorporation of micro-pillars into a fluidic device increases the filling time when compared to comparative devices.

  18. Numerical simulation of viscous flow and hydrodynamic noise in surface ship

    Directory of Open Access Journals (Sweden)

    YU Han

    2017-12-01

    Full Text Available [Objectives] The problem of noise caused by an unsteady flow field around a surface ship is a difficulty facing the stealth design of ship hulls, in which the existence of the free surface makes it different from submarine hydrodynamic noise calculation. To solve this problem,[Methods] the Volume of Fluid(VOF method and SST k-ω turbulence model are combined to simulate the unsteady flow field of the hull, and the free surface is given an air acoustic impedance to simulate the absorption boundary. The pulsating pressure of the hull surface is used as the source of the noise, and the underwater radiation noise of the surface ship is calculated with the acoustic finite element method.[Results] The results show high agreement with the experimental results and previous simulation results. The noise sources are mainly concentrated at the bow of the hull.[Conclusions] The results show that this calculation method can accurately simulate the flow field and sound field of a surface ship, and it can provides valuable reference for the acoustic stealth design of surface ships.

  19. Rational surfaces, ExB sheared flows and transport interplay in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Pedrosa, M.A.; Erents, K.

    2002-01-01

    Experimental evidence of a strong interplay between magnetic topology (rational surfaces) and the generation of ExB sheared flows has been observed in the plasma edge region of stellarator (TJ-II) and tokamak (JET) devices. Both constant and varying in time ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes, but below the power threshold to trigger the formation of transport barriers. Flows driven by fluctuations are candidates to explain these experimental results. (author)

  20. Rational surfaces, ExB sheared flows and transport interplay in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, Carlos; Pedrosa, Maria A.; Erents, Kevin

    2001-01-01

    Experimental evidence of a strong interplay between magnetic topology (rational surfaces) and the generation of ExB sheared flows has been observed in the plasma edge region of stellarator (TJ-II) and tokamak (JET) devices. Constant and varying in time ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. The plasma conditions where this has been observed are clearly below the power threshold to trigger the formation of transport barriers. Flows driven by fluctuations are candidates to explain these experimental results. (author)

  1. Core barrier formation near integer q surfaces in DIII-D

    International Nuclear Information System (INIS)

    Austin, M. E.; Gentle, K. W.; Burrell, K. H.; Waltz, R. E.; Gohil, P.; Greenfield, C. M.; Groebner, R. J.; Petty, C. C.; Prater, R.; Heidbrink, W. W.; Luo, Y.; Kinsey, J. E.; Makowski, M. A.; McKee, G. R.; Shafer, M. W.; Nazikian, R.; Rhodes, T. L.; Van Zeeland, M. A.

    2006-01-01

    Recent DIII-D experiments have significantly improved the understanding of internal transport barriers (ITBs) that are triggered close to the time when an integer value of the minimum in q is crossed. While this phenomenon has been observed on many tokamaks, the extensive transport and fluctuation diagnostics on DIII-D have permitted a detailed study of the generation mechanisms of q-triggered ITBs as pertaining to turbulence suppression dynamics, shear flows, and energetic particle modes. In these discharges, the evolution of the q profile is measured using motional Stark effect polarimetry and the integer q min crossings are further pinpointed in time by the observation of Alfven cascades. High time resolution measurements of the ion and electron temperatures and the toroidal rotation show that the start of improved confinement is simultaneous in all three channels, and that this event precedes the traversal of integer q min by 5-20 ms. There is no significant low-frequency magnetohydrodynamic activity prior to or just after the crossing of the integer q min and hence magnetic reconnection is determined not to be the precipitant of the confinement change. Instead, results from the GYRO code point to the effects of zonal flows near low order rational q values as playing a role in ITB triggering. A reduction in local turbulent fluctuations is observed at the start of the temperature rise and, concurrently, an increase in turbulence poloidal flow velocity and flow shear is measured with the beam emission spectroscopy diagnostic. For the case of a transition to an enduring internal barrier the fluctuation level remains at a reduced amplitude. The timing and nature of the temperature, rotation, and fluctuation changes leading to internal barriers suggests transport improvement due to increased shear flow arising from the zonal flow structures

  2. Comparing two surface flow wetlands for removal of nutrients in agricultural drainage water

    DEFF Research Database (Denmark)

    Hoffmann, Carl Christian; Kjærgaard, Charlotte; Levesen, Bo

    In Denmark there is a growing interest for using constructed wetlands as a mean for removal of nutrients from agricultural run-off, such as drainage ditches and tile drainage systems. We have studied two surface flow constructed wetlands from district Vejle, Jutland, Denmark. The Vicarage Wetland.......020 mg P and unfiltered TP decreases with 75 % to 0.040 mg P l-1. The results from this study seem to indicate that constructed surface flow wetlands are able to remove nitrogen and retain phosphorus from agricultural drainage run-off although the nutrient concentrations are much lower as compared...

  3. Surface profiling of normally responding and nonreleasing basophils by flow cytometry

    DEFF Research Database (Denmark)

    Kistrup, Kasper; Poulsen, Lars Kærgaard; Jensen, Bettina Margrethe

    a maximum release blood mononuclear cells were purified by density centrifugation and using flow cytometry, basophils, defined as FceRIa+CD3-CD14-CD19-CD56-,were analysed for surface expression of relevant markers. All samples were compensated and analysed in logicle display. All gates......c, C3aR, C5aR CCR3, FPR1, ST2, CRTH2 on anti-IgE respondsive and nonreleasing basophils by flow cytometry, thereby generating a surface profile of the two phenotypes. Methods Fresh buffy coat blood (

  4. A new facility for studying plasma interacting with flowing liquid lithium surface

    International Nuclear Information System (INIS)

    Cao, X.; Ou, W.; Tian, S.; Wang, C.; Zhu, Z.; Wang, J.; Gou, F.; Yang, D.; Chen, S.

    2014-01-01

    A new facility to study plasmas interacting with flowing liquid lithium surface was designed and is constructing in Sichuan University. The integrated setup includes the liquid lithium circulating part and linear high density plasma generator. The circulating part is consisted of main loop, on-line monitor system, lithium purification system and temperature programmed desorption system. In our group a linear high density plasma generator was built in 2012. Three coils were mounted along the vessel to produce an axial magnetic field inside. The magnetic field strength is up to 0.45 T and work continuously. Experiments on plasmas interacting with free flowing liquid lithium surface will be performed

  5. On the link between ExB sheared flows and rational surfaces in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Erents, K.; Matthews, G.

    2000-11-01

    Experimental evidence of flattening in plasma profiles has been observed in the edge region of the JET tokamak. This observation has been interpreted in terms of the influence of rational surfaces on plasma profiles. In the framework of this interpretation, significant ExB sheared flows linked to rational surfaces have been identified. These ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. These results can explain the link between the magnetic topology and the generation of transport barriers reported in fusion devices. (author)

  6. Shear induced hexagonal ordering observed in an ionic viscoelastic fluid in flow past a surface

    International Nuclear Information System (INIS)

    Hamilton, W.A.; Butler, P.D.; Baker, S.M.; Smith, G.S.; Hayter, J.B.; Magid, L.J.; Pynn, R.

    1994-01-01

    We present the first clear evidence of a shear induced hexagonal phase in a polyionic fluid in flow past a plane quartz surface. The dilute surfactant solution studied is viscoelastic due to the formation and entanglement of highly extended charged threadlike micelles many thousands of A long, which are known to align along the flow direction under shear. Small-angle neutron diffraction data show that in the high shear region within a few tens of microns of the surface these micelles not only align, but form a remarkably well ordered hexagonal array separated by 370 A, 8 times their 46 A diameter

  7. Synthesis and electrochemical performance of surface-modified nano-sized core/shell tin particles for lithium ion batteries

    International Nuclear Information System (INIS)

    Schmuelling, Guido; Meyer, Hinrich-Wilhelm; Placke, Tobias; Winter, Martin; Oehl, Nikolas; Knipper, Martin; Kolny-Olesiak, Joanna; Plaggenborg, Thorsten; Parisi, Jürgen

    2014-01-01

    Tin is able to lithiate and delithiate reversibly with a high theoretical specific capacity, which makes it a promising candidate to supersede graphite as the state-of-the-art negative electrode material in lithium ion battery technology. Nevertheless, it still suffers from poor cycling stability and high irreversible capacities. In this contribution, we show the synthesis of three different nano-sized core/shell-type particles with crystalline tin cores and different amorphous surface shells consisting of SnO x and organic polymers. The spherical size and the surface shell can be tailored by adjusting the synthesis temperature and the polymer reagents in the synthesis, respectively. We determine the influence of the surface modifications with respect to the electrochemical performance and characterize the morphology, structure, and thermal properties of the nano-sized tin particles by means of high-resolution transmission electron microscopy, x-ray diffraction, and thermogravimetric analysis. The electrochemical performance is investigated by constant current charge/discharge cycling as well as cyclic voltammetry. (paper)

  8. Theoretical Study of Local Surface Plasmon Resonances on a Dielectric-Ag Core-Shell Nanosphere Using the Discrete-Dipole Approximation Method

    International Nuclear Information System (INIS)

    Ma Ye-Wan; Wu Zhao-Wang; Zhang Li-Hua; Liu Wan-Fang; Zhang Jie

    2015-01-01

    The local surface plasmon resonances (LSPRs) of dielectric-Ag core-shell nanospheres are studied by the discretedipole approximation method. The result shows that LSPRs are sensitive to the surrounding medium refractive index, which shows a clear red-shift with the increasing surrounding medium refractive index. A dielectric-Ag core-shell nanosphere exhibits a strong coupling between the core and shell plasmon resonance modes. LSPRs depend on the shell thickness and the composition of dielectric-core and metal-shell. LSPRs can be tuned over a longer wavelength range by changing the ratio of core to shell value. The lower energy mode ω_− shows a red-shift with the increasing dielectric-core value and the inner core radius, while blue-shifted with the increasing outer shell thickness. The underlying mechanisms are analyzed with the plasmon hybridization theory and the phase retardation effect. (paper)

  9. Theory for source-responsive and free-surface film modeling of unsaturated flow

    Science.gov (United States)

    Nimmo, J.R.

    2010-01-01

    A new model explicitly incorporates the possibility of rapid response, across significant distance, to substantial water input. It is useful for unsaturated flow processes that are not inherently diffusive, or that do not progress through a series of equilibrium states. The term source-responsive is used to mean that flow responds sensitively to changing conditions at the source of water input (e.g., rainfall, irrigation, or ponded infiltration). The domain of preferential flow can be conceptualized as laminar flow in free-surface films along the walls of pores. These films may be considered to have uniform thickness, as suggested by field evidence that preferential flow moves at an approximately uniform rate when generated by a continuous and ample water supply. An effective facial area per unit volume quantitatively characterizes the medium with respect to source-responsive flow. A flow-intensity factor dependent on conditions within the medium represents the amount of source-responsive flow at a given time and position. Laminar flow theory provides relations for the velocity and thickness of flowing source-responsive films. Combination with the Darcy-Buckingham law and the continuity equation leads to expressions for both fluxes and dynamic water contents. Where preferential flow is sometimes or always significant, the interactive combination of source-responsive and diffuse flow has the potential to improve prediction of unsaturated-zone fluxes in response to hydraulic inputs and the evolving distribution of soil moisture. Examples for which this approach is efficient and physically plausible include (i) rainstorm-generated rapid fluctuations of a deep water table and (ii) space- and time-dependent soil water content response to infiltration in a macroporous soil. ?? Soil Science Society of America.

  10. Rapid growth of amorphous carbon films on the inner surface of micron-thick and hollow-core fibers

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Longfei [Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Electric Science, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Liu, Dongping, E-mail: Dongping.liu@dlnu.edu.cn [Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Electric Science, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Zhou, Xinwei [Department of Mechanical Engineering, Zhejiang University, Zhejiang 310007 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Ni, Weiyuan [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Niu, Jinhai; Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China)

    2013-10-01

    Ultrathick (> 25 μm) carbon films were obtained on the inner surface of hollow and micron-thick quartz fibers by confining CH{sub 4}/He or C{sub 2}H{sub 2}/He microplasmas in their hollow cores. The resulting carbon films were studied by using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The microplasma-enhanced chemical vapor deposition (CVD) technique resulted in the uniform growth of amorphous carbon films on the inner surface of very long (> 1 m) hollow-core fibers. Film deposition is performed by using microplasmas at atmospheric pressure and at 50 Pa. The carbon films obtained with the latter show the smooth inner surfaces and the well continuity across the film/optical fiber. Low-pressure CH{sub 4}/He and C{sub 2}H{sub 2}/He microplasmas can lead to a rapid growth (∼ 2.00 μm/min) of carbon films with their thickness of > 25 μm. The optical emission measurements show that various hydrocarbon species were formed in these depositing microplasmas due to the collisions between CH{sub 4}/C{sub 2}H{sub 2} molecules and energetic species. The microplasma-enhanced CVD technique running without the complicated fabrication processes shows its potentials for rapidly depositing the overlong carbon tubes with their inner diameters of tens of microns. - Highlights: • The microplasma device is applied for coating deposition inside hollow-core fibers. • The microplasma device results in > 25 μm-thick carbon films. • The microplasma device is simple for deposition of ultralong carbon tubes.

  11. Modeling the Surface Energy Balance of the Core of an Old Mediterranean City: Marseille.

    Science.gov (United States)

    Lemonsu, A.; Grimmond, C. S. B.; Masson, V.

    2004-02-01

    The Town Energy Balance (TEB) model, which parameterizes the local-scale energy and water exchanges between urban surfaces and the atmosphere by treating the urban area as a series of urban canyons, coupled to the Interactions between Soil, Biosphere, and Atmosphere (ISBA) scheme, was run in offline mode for Marseille, France. TEB's performance is evaluated with observations of surface temperatures and surface energy balance fluxes collected during the field experiments to constrain models of atmospheric pollution and transport of emissions (ESCOMPTE) urban boundary layer (UBL) campaign. Particular attention was directed to the influence of different surface databases, used for input parameters, on model predictions. Comparison of simulated canyon temperatures with observations resulted in improvements to TEB parameterizations by increasing the ventilation. Evaluation of the model with wall, road, and roof surface temperatures gave good results. The model succeeds in simulating a sensible heat flux larger than heat storage, as observed. A sensitivity comparison using generic dense city parameters, derived from the Coordination of Information on the Environment (CORINE) land cover database, and those from a surface database developed specifically for the Marseille city center shows the importance of correctly documenting the urban