WorldWideScience

Sample records for augmented flow fields

  1. Aerodynamic structures and processes in rotationally augmented flow fields

    DEFF Research Database (Denmark)

    Schreck, S.J.; Sørensen, Niels N.; Robinson, M.C.

    2007-01-01

    reliably identify and track pertinent features in the rotating blade boundary layer topology as they evolved in response to varying wind speed. Subsequently, boundary layer state was linked to above-surface flow field structure and used to deduce mechanisms; underlying augmented aerodynamic force....... Experimental measurements consisted of surface pressure data statistics used to infer sectional boundary layer state and to quantify normal force levels. Computed predictions included high-resolution boundary layer topologies and detailed above-surface flow field structures. This synergy was exploited to...

  2. MR-venography using manual flow augmentation in an open low field MR system

    International Nuclear Information System (INIS)

    Objective: To evaluate the feasibility of signal enhancement in the deep veins by means of manual compression of the calf (flow augmentation) as a new approach to MR venography in open configuration, low-field systems. Methods: 10 healthy volunteers underwent MR venography of the calf unconstrained and during short localized manual compression. Gradient recalled echo sequences (FLASH, FISP) with repeated single slice acquisition and first-order gradient motion refocussing were tested in four protocols with and without arterial presaturation slabs (scan time 2.2-5.0 s per slice). The effect on flow enhancement was rated by means of a signal score. Interventional accessories, particularly an in-room LCD screen, were required for interactive application of compression manoeuvres. Results: Sequences with arterial presaturation slabs were superior to those without regardless of the longer acquisition times. Careful targeting of compression to the mid-time of data acquisition was crucial to obtain marked flow acceleration. Enhancement was best in the case of proximally applied calf compression. Signal improvement was consistently achieved in the proximal parts of the posterior tibial and peroneal veins, but was only seen in 4/10 volunteers in the distal part of the anterior tibial vein. Conclusion: Flow augmentation by means of manual calf compression is a simple and effective complementary approach to MR venography in open configuration, low field MR systems. (orig.)

  3. Power augmentation measurement and flow field visualisation for coupled Savonius rotors

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, N.; Ogawa, Y.; Shirai, H.

    1988-01-01

    Power augmentation performance and its mechanism in coupled Savonius rotors running in parallel are studied by power measurement and by flow visualisation. It is found from the power measurement that the maximum power occurs with the counter-rotating rotors advancing at the center and the augmentation reaches 27% compared with the single rotor at the same tunnel blockage. The power augmentation mechanism suggested by the smoke-wire visualised results is considered to be due to the wind concentration effected by rotation and by the mutual flow-interaction effect between the rotors. Both effects are strong for counter-rotating rotors advancing at the center, but become weaker for other rotor combinations. This result agrees qualitatively with the measured power augmentation performance in the present experiment. (author).

  4. Modeling dynamic stall on wind turbine blades under rotationally augmented flow fields

    Energy Technology Data Exchange (ETDEWEB)

    Guntur, S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schreck, S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sorensen, N. N. [Technical Univ. of Denmark, Lyngby (Denmark); Bergami, L. [Technical Univ. of Denmark, Lyngby (Denmark)

    2015-04-22

    It is well known that airfoils under unsteady flow conditions with a periodically varying angle of attack exhibit aerodynamic characteristics different from those under steady flow conditions, a phenomenon commonly known as dynamic stall. It is also well known that the steady aerodynamic characteristics of airfoils in the inboard region of a rotating blade differ from those under steady two-dimensional (2D) flow conditions, a phenomenon commonly known as rotational augmentation. This paper presents an investigation of these two phenomena together in the inboard parts of wind turbine blades. This analysis is carried out using data from three sources: (1) the National Renewable Energy Laboratory’s Unsteady Aerodynamics Experiment Phase VI experimental data, including constant as well as continuously pitching blade conditions during axial operation, (2) data from unsteady Delayed Detached Eddy Simulations (DDES) carried out using the Technical University of Denmark’s in-house flow solver Ellipsys3D, and (3) data from a simplified model based on the blade element momentum method with a dynamic stall subroutine that uses rotationally augmented steady-state polars obtained from steady Phase VI experimental sequences, instead of the traditional 2D nonrotating data. The aim of this work is twofold. First, the blade loads estimated by the DDES simulations are compared to three select cases of the N sequence experimental data, which serves as a validation of the DDES method. Results show reasonable agreement between the two data in two out of three cases studied. Second, the dynamic time series of the lift and the moment polars obtained from the experiments are compared to those from the dynamic stall subroutine that uses the rotationally augmented steady polars. This allowed the differences between the stall phenomenon on the inboard parts of harmonically pitching blades on a rotating wind turbine and the classic dynamic stall representation in 2D flow to be

  5. Modeling dynamic stall on wind turbine blades under rotationally augmented flow fields

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Sørensen, Niels N.; Schreck, Scott;

    2016-01-01

    reduced order dynamic stall model that uses rotationally augmented steady-state polars obtained from steady Phase VI experimental sequences, instead of the traditional two-dimensional, non-rotating data. The aim of this work is twofold. First, the blade loads estimated by the DDES simulations are compared...... qualitative agreement between the model and the experimental data in many cases, which suggests that the current two-dimensional dynamic stall model as used in blade element momentum-based aeroelastic codes may provide a reasonably accurate representation of three-dimensional rotor aerodynamics when used in...

  6. MR-venography using manual flow augmentation in an open low field MR system; MR-Venographie am offenen Niederfeldtomographen unter Verwendung manueller Flussaugmentation

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, C.; Wiskirchen, J.; Truebenbach, J.; Timmermann, B.; Pereira, P.; Duda, S.H.; Claussen, C.D. [Tuebingen Univ. (Germany). Abt. fuer Radiologische Diagnostik

    2001-09-01

    Objective: To evaluate the feasibility of signal enhancement in the deep veins by means of manual compression of the calf (flow augmentation) as a new approach to MR venography in open configuration, low-field systems. Methods: 10 healthy volunteers underwent MR venography of the calf unconstrained and during short localized manual compression. Gradient recalled echo sequences (FLASH, FISP) with repeated single slice acquisition and first-order gradient motion refocussing were tested in four protocols with and without arterial presaturation slabs (scan time 2.2-5.0 s per slice). The effect on flow enhancement was rated by means of a signal score. Interventional accessories, particularly an in-room LCD screen, were required for interactive application of compression manoeuvres. Results: Sequences with arterial presaturation slabs were superior to those without regardless of the longer acquisition times. Careful targeting of compression to the mid-time of data acquisition was crucial to obtain marked flow acceleration. Enhancement was best in the case of proximally applied calf compression. Signal improvement was consistently achieved in the proximal parts of the posterior tibial and peroneal veins, but was only seen in 4/10 volunteers in the distal part of the anterior tibial vein. Conclusion: Flow augmentation by means of manual calf compression is a simple and effective complementary approach to MR venography in open configuration, low field MR systems. (orig.) [German] Ziel: Etablierung eines Messprotokolls zur Signalsteigerung in den Unterschenkelvenen durch kurzzeitigen manuellen Druck auf die Wade (Augmentation) bei der MR-Venographie am offenen Niederfeld-MRT. Methode: Bei 10 Probanden wurden MR-venographische Untersuchungen des Unterschenkels in Ruhelage sowie unter manueller Augmentation durchgefuehrt. Vier Sequenzprotokolle mit Gradientenecho-Sequenzen (FLASH, FISP) in serieller Einzelschicht-Akquisition und Flussrephasierung mit und ohne arterielle

  7. Entrainment and thrust augmentation in pulsatile ejector flows

    Science.gov (United States)

    Sarohia, V.; Bernal, L.; Bui, T.

    1981-01-01

    This study comprised direct thrust measurements, flow visualization by use of a spark shadowgraph technique, and mean and fluctuating velocity measurements with a pitot tube and linearized constant temperature hot-wire anemometry respectively. A gain in thrust of as much as 10 to 15% was observed for the pulsatile ejector flow as compared to the steady flow configuration. From the velocity profile measurements, it is concluded that this enhanced augmentation for pulsatile flow as compared to a nonpulsatile one was accomplished by a corresponding increased entrainment by the primary jet flow. It is also concluded that the augmentation and total entrainment by a constant area ejector critically depends upon the inlet geometry of the ejector. Experiments were performed to evaluate the influence of primary jet to ejector area ratio, ejector length, and presence of a diffuser on pulsatile ejector performance.

  8. Magnetic field induced augmented thermal conduction phenomenon in magneto nanocolloids

    OpenAIRE

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K

    2015-01-01

    Magnetic field induced drastically augmented thermal conductivity of magneto nanocolloids involving magnetic oxide nanoparticles, viz. Fe2O3, Fe3O4, Nickel oxide (NiO), Cobalt oxide (Co3O4), dispersed in different base fluids (heat transfer oil, kerosene, and ethylene glycol) have been reported. Experiments reveal the augmented thermal transport under the external applied magnetic field, with kerosene based MNCs showing at relatively low magnetic field intensities as compared to the heat tran...

  9. Augmented reality three-dimensional display with light field fusion.

    Science.gov (United States)

    Xie, Songlin; Wang, Peng; Sang, Xinzhu; Li, Chengyu

    2016-05-30

    A video see-through augmented reality three-dimensional display method is presented. The system that is used for dense viewpoint augmented reality presentation fuses the light fields of the real scene and the virtual model naturally. Inherently benefiting from the rich information of the light field, depth sense and occlusion can be handled under no priori depth information of the real scene. A series of processes are proposed to optimize the augmented reality performance. Experimental results show that the reconstructed fused 3D light field on the autostereoscopic display is well presented. The virtual model is naturally integrated into the real scene with a consistence between binocular parallax and monocular depth cues. PMID:27410076

  10. Augmentation of forced flow boiling heat transfer by introducing air flow into subcooled water flow

    International Nuclear Information System (INIS)

    The effect of air injection into a subcooled water flow on boiling heat transfer and a critical heat flux (CHF) was examined experimentally. Experiments were conducted in the range of subcooling of 50 K, a superficial velocity of water and air Ul = 0.17 ∼ 3.4 and Ug = 0 ∼ 15 m/s, respectively. A test heat transfer surface was a 5 mm wide, 40 mm long and 0.5 mm thick stainless steel sheet embedded on the bottom wall of a 10 mm high and 20 mm wide rectangular flow channel. Nine times enhancement of the heat transfer coefficient in the non-boiling region was attained at the most by introducing an air flow into a water single-phase flow. The heat transfer improvement was prominent when the water flow rate was low and the air introduction was large. The present results of the non-boiling heat transfer were well correlated with the Lockhart-Martinelli parameter Xtt; hTP/hL0 = 5.0(1/ Xtt)0.5. The air introduction has some effect on the augmentation of heat transfer in the boiling region, however, the two-phase flow effect was little and the boiling was dominant in the fully developed boiling region. The CHF was improved a little by the air introduction in the high water flow region. However, that was rather greatly reduced in the low flow region. Even so, the general trend by the air introduction was that qCHF increased as the air introduction was increased. The heat transfer augmentation in the non-boiling region was attained by less power increase than that in the case that only the water flow rate was increased. From the aspect of the power consumption and the heat transfer enhancement, the small air introduction in the low water flow rate region seemed more profitable, although the air introduction in the high water flow rate region and also the large air introduction were still effective in the augmentation of the heat transfer in the non-boiling region. (author)

  11. Field-Flow Fractionation.

    Science.gov (United States)

    Caldwell, Karin D.

    1988-01-01

    Describes a technique for separating samples that range over 15 orders of magnitude in molecular weight. Discusses theory, apparatus, and sample preparation techniques. Lists several types of field-flow fractionation (FFF) and their uses: sedimentation FFF, thermal FFF, flow FFF, electrical FFF, and steric FFF. (ML)

  12. ARSC: Augmented Reality Student Card--An Augmented Reality Solution for the Education Field

    Science.gov (United States)

    El Sayed, Neven A. M.; Zayed, Hala H.; Sharawy, Mohamed I.

    2011-01-01

    Augmented Reality (AR) is the technology of adding virtual objects to real scenes through enabling the addition of missing information in real life. As the lack of resources is a problem that can be solved through AR, this paper presents and explains the usage of AR technology we introduce Augmented Reality Student Card (ARSC) as an application of…

  13. The Effects of Augmented Levels of Stress on Reaction Time in the Peripheral Visual Field

    Science.gov (United States)

    Reynolds, Harriet L.

    1976-01-01

    The purpose of this study was to determine if reaction time in the peripheral visual field and size of the functional visual field were altered by augmented levels of physical stress while performing on a bicycle ergometer. (JD)

  14. New unstructured discretizations for fluid flows with augmented incompressibility

    International Nuclear Information System (INIS)

    In this research thesis belonging to the field of numerical analysis, the author addresses the discretization of Stokes and Navier-Stokes equations which are used to model incompressible flows on two- and three-dimensional unstructured grids by using a finite volume element method. The author presents the physical and mathematical modelling (Stokes and Navier-Stokes equations, theoretical framework for mathematical analysis). He addresses the discretization of Stokes equations and presents the finite volume element method which uses the finite element used in the Priceles code. Some drawbacks of this element are outlined and improvements are then proposed, first within the finite element framework, and then within the finite volume element framework. The new element is theoretically analysed and convergence results are given. As some problems remained, the discretization is slightly modified and gives good results. Then, the author addresses the discretization of Navier Stokes equations. Attention is paid to diffusion terms and convection terms. Neumann boundary conditions are taken into account. The results of three different calculations are presented and analysed

  15. Convective Heat Transfer Augmentation by Flexible fins in Laminar Channel Pulsating flow

    CERN Document Server

    Joshi, Rakshitha U; Bhardwaj, Rajneesh

    2015-01-01

    Fluid-structure interaction (FSI) of thin flexible fins coupled with convective heat transfer has applications in energy harvesting and in understanding functioning of several biological systems. We numerically investigate FSI of the thin flexible fins involving large-scale flow-induced deformation as a potential heat transfer enhancement technique. An in-house, strongly-coupled fluid-structure interaction (FSI) solver is employed in which flow and structure solvers are based on sharp-interface immersed boundary and finite element method, respectively. We consider twin flexible fins in a heated channel with laminar pulsating cross flow. The vortex ring past the fin sweep higher sources of vorticity generated on the channel walls out into the downstream - promoting the mixing of the fluid. The moving fin assists in convective mixing, augmenting convection in bulk and at the walls; and thereby reducing thermal boundary layer thickness and improving heat transfer at the channel walls. The thermal augmentation is...

  16. Flow field analysis

    Science.gov (United States)

    Cliff, W. C.; Verholek, M. G.

    1978-01-01

    The average mean wind speed integrated over a disk is shown to be extremely close to the mean value of wind speed which would be measured at the center of a disk for most geometries in which a WECS (Wind Energy Conversion System) would operate. Field test results are presented which compare instantaneous records of wind speed integrated over a disk with the wind speed measured at the center of the disk. The wind field that a rotating element would experience is presented which was synthesized from the outputs of an array of anemometers.

  17. Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images

    Science.gov (United States)

    Watson, Jeffrey R.; Gainer, Christian F.; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G. Michael, Jr.; Anton, Rein; Romanowski, Marek

    2015-10-01

    Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

  18. Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images.

    Science.gov (United States)

    Watson, Jeffrey R; Gainer, Christian F; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G Michael; Anton, Rein; Romanowski, Marek

    2015-10-01

    Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures. PMID:26440760

  19. An Evaluation of the Effectiveness of Flow Augmentation in the Snake River, 1991-1995 : Phase I: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, Albert E.; Schlecte, J.Warren [Bio Analysts, Inc., Redmond, WA (United States)]|[HDR Engineering, Inc., Salt Lake City, UT (United States)

    1997-07-01

    The purpose of this evaluation was to estimate the volume and shape of flow augmentation water delivered in the Snake Basin during the years 1991 through 1995, and to assess the biological consequences to ESA-listed salmon stocks in that drainage. HDR Engineering, Inc. calculated flow augmentation estimates and compared their values to those reported by agencies in the Northwest. BioAnalysts, Inc. conducted the biological evaluation.

  20. An evaluation of the effectiveness of flow augmentation in the Snake River, 1991-1995. Phase 1: Final report

    International Nuclear Information System (INIS)

    The purpose of this evaluation was to estimate the volume and shape of flow augmentation water delivered in the Snake Basin during the years 1991 through 1995, and to assess the biological consequences to ESA-listed salmon stocks in that drainage. HDR Engineering, Inc. calculated flow augmentation estimates and compared their values to those reported by agencies in the Northwest. BioAnalysts, Inc. conducted the biological evaluation

  1. Augmented Reality in a Simulated Tower Environment: Effect of Field of View on Aircraft Detection

    Science.gov (United States)

    Ellis, Stephen R.; Adelstein, Bernard D.; Reisman, Ronald J.; Schmidt-Ott, Joelle R.; Gips, Jonathan; Krozel, Jimmy; Cohen, Malcolm (Technical Monitor)

    2002-01-01

    An optical see-through, augmented reality display was used to study subjects' ability to detect aircraft maneuvering and landing at the Dallas Ft. Worth International airport in an ATC Tower simulation. Subjects monitored the traffic patterns as if from the airport's western control tower. Three binocular fields of view (14 deg, 28 deg and 47 deg) were studied in an independent groups' design to measure the degradation in detection performance associated with the visual field restrictions. In a second experiment the 14 deg and 28 deg fields were presented either with 46% binocular overlap or 100% overlap for separate groups. The near asymptotic results of the first experiment suggest that binocular fields of view much greater than 47% are unlikely to dramatically improve performance; and those of the second experiment suggest that partial binocular overlap is feasible for augmented reality displays such as may be used for ATC tower applications.

  2. Analysis of liposomes using asymmetrical flow field-flow fractionation

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Decker, Christiane; Fahr, Alfred

    2012-01-01

    Liposomes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol were analyzed by asymmetrical flow field-flow fractionation coupled with multi-angle laser light scattering. In addition to evaluation of fractionation conditions (flow conditions, sample mass, carrier liquid...

  3. Augmenting an observation network to facilitate flow and transport model discrimination

    Science.gov (United States)

    Pachepsky, Y. A.; Kuznetsov, M.; Guber, A.; Yakirevich, A.; Martinez Garcia, G.; Gish, T. J.; Cady, R.; Nicholson, T. J.

    2011-12-01

    Improving understanding of subsurface conditions includes performance comparison for competing models, independently developed or obtained via model abstraction. The model comparison and discrimination can be improved if additional observations will be included. The objective of this work was to implement and to test a Bayesian method for the sequential design of the network augmentation. The method is based on (1) generalization of Kullback's discriminant function and "weights of evidence" for the case of available prior probabilities, (2) ensemble modeling to estimate variance of the predicted values. The method was tested with the data from the tracer experiment at the USDA-ARS OPE3 integrated research site. A pulse of KCL solution was applied to an irrigation plot, and chloride concentrations were measured in the groundwater at three sampling depths in 12 observations wells. The spatial distribution of soil materials was obtained from cores taken from depths of 0-200 cm with 20 cm increment during installation of observation wells. A three-dimension flow and transport model was developed to simulate the flow and chloride transport for the tracer experiment at the OPE3 site. The manual calibration of hydraulic conductivities and dispersivities was performed, and pedotransfer functions were conditioned to calibration results to build ensemble of models. The search of the optimal location of the augmentation wells was done on a 2D grid. Models of different complexity were compared. Both single and multiple responses were used to discriminate models. The outcome of this study can provide the information for the future data collection and monitoring efforts to further reduce the uncertainty

  4. A Mixed Methods Assessment of Students' Flow Experiences during a Mobile Augmented Reality Science Game

    Science.gov (United States)

    Bressler, D. M.; Bodzin, A. M.

    2013-01-01

    Current studies have reported that secondary students are highly engaged while playing mobile augmented reality (AR) learning games. Some researchers have posited that players' engagement may indicate a flow experience, but no research results have confirmed this hypothesis with vision-based AR learning games. This study investigated factors…

  5. Dose-remission of pulsating electromagnetic fields as augmentation in therapy-resistant depression

    DEFF Research Database (Denmark)

    Straasø, Birgit; Lauritzen, Lise; Lunde, Marianne;

    2014-01-01

    OBJECTIVE: To evaluate to what extent a twice daily dose of Transcranial Pulsating ElectroMagnetic Fields (T-PEMF) was superior to once daily in patients with treatment-resistant depression as to obtaining symptom remission after 8 weeks of augmentation therapy. METHODS: A self-treatment set-up of...... (active dose in the morning and sham in the afternoon) or two T-PEMF doses (active dose both morning and afternoon) in a double-blind procedure. A score of 7 or less on the Hamilton Depression Scale (HAM-D17) was the criterion of remission. RESULTS: In total 34 patients received active T-PEMF once a day...

  6. Gradient-augmented hybrid interface capturing method for incompressible two-phase flow

    Science.gov (United States)

    Zheng, Fu; Shi-Yu, Wu; Kai-Xin, Liu

    2016-06-01

    Motivated by inconveniences of present hybrid methods, a gradient-augmented hybrid interface capturing method (GAHM) is presented for incompressible two-phase flow. A front tracking method (FTM) is used as the skeleton of the GAHM for low mass loss and resources. Smooth eulerian level set values are calculated from the FTM interface, and are used for a local interface reconstruction. The reconstruction avoids marker particle redistribution and enables an automatic treatment of interfacial topology change. The cubic Hermit interpolation is employed in all steps of the GAHM to capture subgrid structures within a single spacial cell. The performance of the GAHM is carefully evaluated in a benchmark test. Results show significant improvements of mass loss, clear subgrid structures, highly accurate derivatives (normals and curvatures) and low cost. The GAHM is further coupled with an incompressible multiphase flow solver, Super CE/SE, for more complex and practical applications. The updated solver is evaluated through comparison with an early droplet research. Project supported by the National Natural Science Foundation of China (Grant Nos. 10972010, 11028206, 11371069, 11372052, 11402029, and 11472060), the Science and Technology Development Foundation of China Academy of Engineering Physics (CAEP), China (Grant No. 2014B0201030), and the Defense Industrial Technology Development Program of China (Grant No. B1520132012).

  7. Field programming in gravitational field-flow fractionation

    Czech Academy of Sciences Publication Activity Database

    Chmelík, Josef; Plocková, Jana

    Amsterdam, 2002, s. A-12. [FFF'02. International Symposium on Field-Flow Fractionation /10./. Amsterdam (NL), 02.07.2002-05.07.2002] R&D Projects: GA AV ČR IAA4031805 Institutional research plan: CEZ:AV0Z4031919 Keywords : gravitational field-flow fractionation * field programming * hydrodynamic lift forces Subject RIV: CB - Analytical Chemistry, Separation

  8. Efficient algorithms for Asymmetric Flow Field Flow Fractionation

    OpenAIRE

    Nagapetyan, Tigran

    2014-01-01

    This thesis is devoted to the modeling and simulation of Asymmetric Flow Field Flow Fractionation, which is a technique for separating particles of submicron scale. This process is a part of large family of Field Flow Fractionation techniques and has a very broad range of industrial applications, e. g. in microbiology, chemistry, pharmaceutics, environmental analysis. Mathematical modeling is crucial for this process, as due to the own nature of the process, lab ex- periments are difficult...

  9. Numerical simulation of steady flow fields in coiled flow inverter

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vimal; Nigam, K.D.P. [Department of Chemical Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110 016 (India)

    2005-11-01

    Flatter velocity profiles and more uniform thermal environments are extremely desirous factors for improved performance in flow reactors and heat exchangers. One means of achieving it in laminar flow systems is to use mixers and flow inverters. In the present study a new device is introduced based on the flow inversion by changing the direction of centrifugal force in helically coiled tubes. The objective of the present study is to characterize flow development and temperature fields in the proposed device made up from the configurations of bent coils. The main mechanism generating the flow is the production of spatially chaotic path by changing the direction of flow using a 90{sup o} bend in helical coils (alternating Dean flow). If the direction of centrifugal force is rotated by any angle, the plane of vortex formation also rotates with the same angle. Thus in helical flow a 90{sup o} shift in the direction of centrifugal force cause a complete flow inversion. Complete flow fields and thermal fields in helical coil and bent coil configuration were studied using computational fluid dynamics software (FLUENT 6.0). The three-dimensional governing equations for momentum and energy under the laminar flow conditions were solved with a control-volume finite difference method (CVFDM) with second-order accuracy. The flow pattern obtained for the helical coil was in good agreement to those observed by the previous investigators [S.W. Jones, O.M. Thomas, H. Aref, Chaotic advection by laminar flow in twisted pipe. J. Fluid Mech. 209 (1989) 335-357; Ch. Duchene, H. Peerhossaini, P.J. Michard, On the velocity field and tracer patterns in a twisted duct flow. Phys. Fluids 7 (1995) 1307-1317]. The comparison of the flow fields and temperature fields in the helical tube and bent coil configuration are discussed. The bent coil configuration shows a 20-30% enhancement in the heat transfer due to chaotic mixing while relative pressure drop is 5-6%. The results of the present study

  10. Interactive Near-Field Illumination for Photorealistic Augmented Reality with Varying Materials on Mobile Devices.

    Science.gov (United States)

    Rohmer, Kai; Buschel, Wolfgang; Dachselt, Raimund; Grosch, Thorsten

    2015-12-01

    At present, photorealistic augmentation is not yet possible since the computational power of mobile devices is insufficient. Even streaming solutions from stationary PCs cause a latency that affects user interactions considerably. Therefore, we introduce a differential rendering method that allows for a consistent illumination of the inserted virtual objects on mobile devices, avoiding delays. The computation effort is shared between a stationary PC and the mobile devices to make use of the capacities available on both sides. The method is designed such that only a minimum amount of data has to be transferred asynchronously between the participants. This allows for an interactive illumination of virtual objects with a consistent appearance under both temporally and spatially varying real illumination conditions. To describe the complex near-field illumination in an indoor scenario, HDR video cameras are used to capture the illumination from multiple directions. In this way, sources of illumination can be considered that are not directly visible to the mobile device because of occlusions and the limited field of view. While our method focuses on Lambertian materials, we also provide some initial approaches to approximate non-diffuse virtual objects and thereby allow for a wider field of application at nearly the same cost. PMID:26529458

  11. FreshAiR and Field Studies—Augmenting Geological Reality with Mobile Devices

    Science.gov (United States)

    De Paor, D. G.; Crompton, H.; Dunleavy, M.

    2014-12-01

    During the last decade, mobile devices have fomented a revolution in geological mapping. Present Clinton set the stage for this revolution in the year 2000 when he ordered a cessation to Selective Availability, making reliable GPS available for civilian use. Geologists began using personal digital assistants and ruggedized tablet PCs for geolocation and data recording and the pace of change accelerated with the development of mobile apps such as Google Maps, digital notebooks, and digital compass-clinometers. Despite these changes in map-making technologies, most students continue to learn geology in the field the old-fashioned way, by following a field trip leader as a group and trying to hear and understand lecturettes at the outcrop. In this presentation, we demonstrate the potential of a new Augment Reality (AR) mobile app called "FreshAiR" to change fundamentally the way content-knowledge and learning objectives are delivered to students in the field. FreshAiR, which was developed by co-author and ODU alumnus M.D., triggers content delivery to mobile devices based on proximity. Students holding their mobile devices to the horizon see trigger points superimposed on the field of view of the device's built-in camera. When they walk towards the trigger, information about the location pops up. This can include text, images, movies, and quiz questions (multiple choice and fill-in-the-blank). Students can use the app to reinforce the field trip leader's presentations or they can visit outcrops individuals at different times. This creates the possibility for asynchronous field class, a concept that has profound implications for distance education in the geosciences.

  12. SRMAFTE facility checkout model flow field analysis

    Science.gov (United States)

    Dill, Richard A.; Whitesides, Harold R.

    1992-07-01

    The Solid Rocket Motor Air Flow Equipment (SRMAFTE) facility was constructed for the purpose of evaluating the internal propellant, insulation, and nozzle configurations of solid propellant rocket motor designs. This makes the characterization of the facility internal flow field very important in assuring that no facility induced flow field features exist which would corrupt the model related measurements. In order to verify the design and operation of the facility, a three-dimensional computational flow field analysis was performed on the facility checkout model setup. The checkout model measurement data, one-dimensional and three-dimensional estimates were compared, and the design and proper operation of the facility was verified. The proper operation of the metering nozzles, adapter chamber transition, model nozzle, and diffuser were verified. The one-dimensional and three-dimensional flow field estimates along with the available measurement data are compared.

  13. Visualization of numerically simulated aerodynamic flow fields

    International Nuclear Information System (INIS)

    The focus of this paper is to describe the development and the application of an interactive integrated software to visualize numerically simulated aerodynamic flow fields so as to enable the practitioner of computational fluid dynamics to diagnose the numerical simulation and to elucidate essential flow physics from the simulation. The input to the software is the numerical database crunched by a supercomputer and typically consists of flow variables and computational grid geometry. This flow visualization system (FVS), written in C language is targetted at the Personal IRIS Workstations. In order to demonstrate the various visualization modules, the paper also describes the application of this software to visualize two- and three-dimensional flow fields past aerodynamic configurations which have been numerically simulated on the NEC-SXIA Supercomputer. 6 refs

  14. Free surface transition and momentum augmentation of liquid flow in Micro/Nano-scale channels with hydrophobic and hydrophilic surfaces

    International Nuclear Information System (INIS)

    We propose a novel micro/nano-scale nozzle structure, featuring an interfacial line between the hydrophilic and the hydrophobic surfaces for a jetting system, such as an inkjet head or electrospray devices. This research will investigate the impact of the interfacial line on flow instability and momentum augmentation as the liquid meniscus moves across the line. The research methods used in this paper, in respect to micro-and nano-scale channels, are computational fluid dynamics (CFD) and non-equilibrium molecular dynamics (MD), respectively. With the growing interest in micro/ nano electromechanical systems (MEMS/NEMS), many studies have been conducted to develop an advanced micro/ nanofluidic system. However, until now, there have been few in-depth studies on passive flow control in micro and nano nozzles using the hydrophilic and hydrophobic surface characteristics. In this research, the sequential arrangement of hydrophilic and hydrophobic surfaces in the nozzle is presented along with an investigation into how flow instability and momentum augmentation are going to be applied to an efficient micro/nano jetting system. When a liquid meniscus arrives at the interfacial line between hydrophilic and hydrophobic surfaces, the meniscus shape changes from concave to convex and the fluid motion near the wall stops until the concave shape is fully converted. Because the momentum should be conserved, the lost momentum near the wall transfers to the center region, and therefore the liquid at the center region is accelerated as it crosses the line. If we use this nozzle structure and the augmentation of the momentum near the center, a tiny droplet can be easily generated

  15. The gradient flow in simple field theories

    CERN Document Server

    Monahan, Christopher

    2015-01-01

    The gradient flow is a valuable tool for the lattice community, with applications from scale-setting to implementing chiral fermions. Here I focus on the gradient flow as a means to suppress power-divergent mixing. Power-divergent mixing stems from the hypercubic symmetry of the lattice regulator and is a particular difficulty for calculations of, for example, high moments of parton distribution functions. The gradient flow removes power-divergent mixing on the lattice, provided the flow time is kept fixed in physical units, at the expense of introducing a new physical scale in the continuum. One approach to dealing with this new scale is the smeared operator product expansion, a formalism that systematically connects nonperturbative calculations of flowed operators to continuum physics. I study the role of the gradient flow in suppressing power-divergent mixing and present the first nonperturbative study in scalar field theory.

  16. Impeller flow field measurement and analysis

    Science.gov (United States)

    Fagan, J. R.; Fleeter, S.

    1991-01-01

    A series of experiments are performed to investigate and quantify the three-dimensional mean flow field in centrifugal compressor flow passages and to evaluate contemporary internal flow models. The experiments include the acquisition and analysis of LDV data in the impeller passages of a low-speed moderate-scale research mixed-flow centrifugal compressor operating at its design point. Predictions from a viscous internal flow model are then correlated with these data. The LDV data show the traditional jet-wake structure observed in many centrifugal compressors, with the wake observed along the shroud 70 percent of the length from the pressure to suction surface. The viscous model predicts the major flow phenomena. However, the correlations of the viscous predictions with the LDV data were poor.

  17. Augmenting the field experience: a student-led comparison of techniques and technologies

    OpenAIRE

    Priestnall, Gary; Brown, Elizabeth; Sharples, Mike; Polmear, Gemma

    2010-01-01

    In this study we report on our experiences of creating and running a student fieldtrip exercise which allowed students to compare a range of approaches to the design of technologies for augmenting landscape scenes. The main study site is around Keswick in the English Lake District, Cumbria, UK, an attractive upland environment popular with tourists and walkers. The aim of the exercise for the students was to assess the effectiveness of various forms of geographic information in augmenting rea...

  18. Experimenting with electromagnetism using augmented reality: Impact on flow student experience and educational effectiveness

    OpenAIRE

    Ibáñez, María Blanca; Di Serio, Angela; Villarán, Diego; Delgado Kloos, Carlos

    2014-01-01

    Educational researchers have recognized Augmented Reality (AR) as a technology with great potential to impact affective and cognitive learning outcomes. However, very little work has been carried out to substantiate these claims. The purpose of this study was to assess to which extent an AR learning application affects learners' level of enjoyment and learning effectiveness. The study followed an experimental/control group design using the type of the application (AR-based, web-based) as inde...

  19. Augmented Reality in Astrophysics

    CERN Document Server

    Vogt, Frédéric P A

    2013-01-01

    Augmented Reality consists of merging live images with virtual layers of information. The rapid growth in the popularity of smartphones and tablets over recent years has provided a large base of potential users of Augmented Reality technology, and virtual layers of information can now be attached to a wide variety of physical objects. In this article, we explore the potential of Augmented Reality for astrophysical research with two distinct experiments: (1) Augmented Posters and (2) Augmented Articles. We demonstrate that the emerging technology of Augmented Reality can already be used and implemented without expert knowledge using currently available apps. Our experiments highlight the potential of Augmented Reality to improve the communication of scientific results in the field of astrophysics. We also present feedback gathered from the Australian astrophysics community that reveals evidence of some interest in this technology by astronomers who experimented with Augmented Posters. In addition, we discuss p...

  20. Improved modeling techniques for turbomachinery flow fields

    Energy Technology Data Exchange (ETDEWEB)

    Lakshminarayana, B. [Pennsylvania State Univ., University Park, PA (United States); Fagan, J.R. Jr. [Allison Engine Company, Indianapolis, IN (United States)

    1995-10-01

    This program has the objective of developing an improved methodology for modeling turbomachinery flow fields, including the prediction of losses and efficiency. Specifically, the program addresses the treatment of the mixing stress tensor terms attributed to deterministic flow field mechanisms required in steady-state Computational Fluid Dynamic (CFD) models for turbo-machinery flow fields. These mixing stress tensors arise due to spatial and temporal fluctuations (in an absolute frame of reference) caused by rotor-stator interaction due to various blade rows and by blade-to-blade variation of flow properties. These tasks include the acquisition of previously unavailable experimental data in a high-speed turbomachinery environment, the use of advanced techniques to analyze the data, and the development of a methodology to treat the deterministic component of the mixing stress tensor. Penn State will lead the effort to make direct measurements of the momentum and thermal mixing stress tensors in high-speed multistage compressor flow field in the turbomachinery laboratory at Penn State. They will also process the data by both conventional and conditional spectrum analysis to derive momentum and thermal mixing stress tensors due to blade-to-blade periodic and aperiodic components, revolution periodic and aperiodic components arising from various blade rows and non-deterministic (which includes random components) correlations. The modeling results from this program will be publicly available and generally applicable to steady-state Navier-Stokes solvers used for turbomachinery component (compressor or turbine) flow field predictions. These models will lead to improved methodology, including loss and efficiency prediction, for the design of high-efficiency turbomachinery and drastically reduce the time required for the design and development cycle of turbomachinery.

  1. Entrainment and mixing in thrust augmenting ejectors

    Science.gov (United States)

    Bernal, L.; Sarohia, V.

    1983-01-01

    An experimental investigation of two-dimensional thrust augmenting ejector flows has been conducted. Measurements of the shroud surface pressure distribution, mean velocity, turbulent intensities and Reynolds stresses were made in two shroud geometries at various primary nozzle pressure ratios. The effects of shroud geometry and primary nozzle pressure ratio on the shroud surface pressure distribution, mean flow field and turbulent field were determined. From these measurements the evolution of mixing within the shroud of the primary flow and entrained fluid was obtained. The relationship between the mean flow field, the turbulent field and the shroud surface pressure distribution is discussed.

  2. Elution modes in field-flow fractionation

    Czech Academy of Sciences Publication Activity Database

    Chmelík, Josef

    New York : Marcel Dekker, 2001, s. 303-306 ISBN 0-8247-0511-4 R&D Projects: GA AV ČR IAA4031805 Institutional research plan: CEZ:AV0Z4031919 Keywords : Field-flow fractionation * elution modes Subject RIV: CB - Analytical Chemistry, Separation

  3. Flow field mapping in data rack model

    Directory of Open Access Journals (Sweden)

    Matěcha J.

    2013-04-01

    Full Text Available The main objective of this study was to map the flow field inside the data rack model, fitted with three 1U server models. The server model is based on the common four-processor 1U server. The main dimensions of the data rack model geometry are taken fully from the real geometry. Only the model was simplified with respect to the greatest possibility in the experimental measurements. The flow field mapping was carried out both experimentally and numerically. PIV (Particle Image Velocimetry method was used for the experimental flow field mapping, when the flow field has been mapped for defined regions within the 2D/3D data rack model. Ansys CFX and OpenFOAM software were used for the numerical solution. Boundary conditions for numerical model were based on data obtained from experimental measurement of velocity profile at the output of the server mockup. This velocity profile was used as the input boundary condition in the calculation. In order to achieve greater consistency of the numerical model with experimental data, the numerical model was modified with regard to the results of experimental measurements. Results from the experimental and numerical measurements were compared and the areas of disparateness were identified. In further steps the obtained proven numerical model will be utilized for the real geometry of data racks and data.

  4. The effect of heat transfer augmentation on two-phase flow instabilities in a vertical boiling channel

    International Nuclear Information System (INIS)

    Experimental and theoretical work have been carried out to find out the effects of heat transfer augmentation on two-phase flow instabilities in a single channel system. The effect of mass flow rate, heat input and inlet subcooling on the system behavior is studied using Freon-11 as the test fluid and six different heater surfaces are tested at various experimental conditions. Experimental evaluation is done using the steady-state pressure drop versus mass flow rate curves along with the curves of additional inlet pressure drop required to stabilize the system during the oscillations, and tables generated using the experimental data. Homogeneous equilibrium flow model and finite differences are used in theoretical analysis. An empirical relationship is obtained to calculate the pressure drop across the exit restriction. Characteristic equation for the system is found by linearizing the dynamic equations of the overall system and analyzed to determine the oscillation thresholds. The results are found to be conservative but in good agreement with the experimental findings

  5. Heating Augmentation in Laminar Flow Due to Heat-Shield Cavities on the Project Orion CEV

    Science.gov (United States)

    Hollis, Brian R.

    2008-01-01

    An experimental study has been conducted to assess the effects of compression pad cavities on the aeroheating environment of the Project Orion CEV heat-shield at laminar conditions. Testing was conducted in Mach 6 and Mach 10 perfect-gas wind tunnels to obtain heating measurements on and around the compression pads using global phosphor thermography. Consistent trends in heating augmentation levels were observed in the data and correlations of average and maximum heating at the cavities were formulated in terms of the local boundary-layer parameters and cavity dimensions. Additional heating data from prior testing of Genesis and Mars Science Laboratory models were also examined to extend the parametric range of cavity heating correlations.

  6. Interactive flow field around two Savonius turbines

    Energy Technology Data Exchange (ETDEWEB)

    Shigetomi, Akinari; Murai, Yuichi; Tasaka, Yuji; Takeda, Yasushi [Laboratory for Flow Control, Division of Energy and Environmental System, Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628 (Japan)

    2011-02-15

    The use of a Savonius type of vertical axis wind turbine is expanding in urban environments as a result of its ability to withstand turbulence as well as its relatively quiet operation. In the past, single turbine performance has been investigated primarily for determining the optimum blade configuration. In contrast, combining multiple Savonius turbines in the horizontal plane produces extra power in particular configurations. This results from the interaction between the two flow fields around individual turbines. To understand quantitatively the interaction mechanism, we measured the flow field around two Savonius turbines in close configurations using particle image velocimetry. The phase-averaged flow fields with respect to the rotation angle of the turbines revealed two types of power-improvement interactions. One comes from the Magnus effect that bends the main stream behind the turbine to provide additional rotation of the downstream turbine. The other is obtained from the periodic coupling of local flow between the two turbines, which is associated with vortex shedding and cyclic pressure fluctuations. Use of this knowledge will assist the design of packaged installations of multiple Savonius turbines. (author)

  7. Field emission microplasma actuation for microchannel flows

    Science.gov (United States)

    Sashank Tholeti, Siva; Shivkumar, Gayathri; Alexeenko, Alina A.

    2016-06-01

    Microplasmas offer attractive flow control methodology for gas transport in microsystems where large viscous losses make conventional pumping methods highly inefficient. We study microscale flow actuation by dielectric-barrier discharge (DBD) with field emission (FE) of electrons, which allows lowering the operational voltage from kV to a few hundred volts and below. A feasibility study of FE-DBD for flow actuation is performed using 2D particle-in-cell method with Monte Carlo collisions (PIC/MCC) at 10 MHz in nitrogen at atmospheric pressure. The free diffusion dominated, high velocity field emission electrons create a large positive space charge and a body force on the order of 106 N m‑3. The body force and Joule heat decrease with increase in dielectric thickness and electrode thickness. The body force also decreases at lower pressures. The plasma body force distribution along with the Joule heating is then used in the Navier–Stokes simulations to quantify the flow actuation in a microchannel. Theoretical analysis and simulations for plasma actuated planar Poiseuille flow show that the gain in flow rate is inversely proportional to Reynolds number. This theoretical analysis is in good agreement with the simulations for a microchannel with closely placed actuators under incompressible conditions. Flow rate of FE-DBD driven 2D microchannel is around 100 ml min‑1 mm‑1 for an input power of 64 μW mm‑1. The gas temperature rises by 1500 K due to the Joule heating, indicating FE-DBD’s potential for microcombustion, micropropulsion and chemical sensing in addition to microscale pumping and mixing applications.

  8. Flow Field of a Human Cough

    Science.gov (United States)

    Hertzberg, Jean

    2005-11-01

    Cough generated infectious aerosols are of interest while developing strategies for the mitigation of disease risks ranging from the common cold to SARS. In this work, the velocity field of human cough was measured using particle image velocimetry (PIV). The project subjects (total 29) coughed into an enclosure seeded with stage fog for most measurements. Cough flow speed profiles, average widths of the cough jet, waveform, and maximum cough speeds were measured. Maximum cough speeds ranged from 1.5 m/s to 28.8 m/s. No correlation was found for maximum cough flow speeds to height or gender. The slow growth of the width of the cough flow suggests that a cough may penetrate farther into a room than a steady jet of similar volume. The velocity profile was found to scale with the square root of downstream distance.

  9. On the no-field method for void time determination in flow field-flow fractionation.

    Science.gov (United States)

    Martin, Michel; Hoyos, Mauricio

    2011-07-01

    Elution time measurements of colloidal particles injected in a symmetrical flow field-flow fractionation (flow FFF) system when the inlet and outlet cross-flow connections are closed have been performed. This no-field method has been proposed earlier for void time (and void volume) determination in flow FFF Giddings et al. (1977). The elution times observed were much larger than expected on the basis of the channel geometrical volume and the flow rate. In order to explain these discrepancies, a flow model allowing the carrier liquid to flow through the porous walls toward the reservoirs located behind the porous elements and along these reservoirs was developed. The ratio between the observed elution time and expected one is found to depend only on a parameter which is a function of the effective permeability and thickness of the porous elements and of the channel thickness and length. The permeabilities of the frits used in the system were measured. Their values lead to predicted elution times in reasonable agreement with experimental ones, taking into account likely membrane protrusion inside the channel on system assembly. They comfort the basic feature of the flow model, in the no-field case. The carrier liquid mostly bypasses the channel to flow along the system mainly in the reservoir. It flows through the porous walls toward the reservoirs near channel inlet and again through the porous walls from the reservoirs to the channel near channel outlet before exiting the system. In order to estimate the extent of this bypassing process, it is desirable that the hydrodynamic characteristics of the permeable elements (permeability and thickness) are provided by flow FFF manufacturers. The model applies to symmetrical as well as asymmetrical flow FFF systems. PMID:21256498

  10. Flow stability of liquid metal flow under transverse magnetic field

    International Nuclear Information System (INIS)

    A stability analysis of a viscous incompressible liquid metal flow in an annular linear induction electromagnetic pump for sodium coolant circulation of LMR (Liquid Metal Reactors ) is carried out when transverse magnetic fields permeate an electrically conducting sodium fluid across the narrow annular gap. Due to a negligible skin effect, the radial magnetic field is assumed to be constant over the narrow channel gap, and the steady state solution of an axial velocity is obtained as a function of radius r. Small perturbations for MHD fields in the form of f(r)ej(wt-k·r), where w is the angular frequency and k is the wave vector of perturbation, are considered and perturbed MHD equations are linearized. The solutions of the perturbed equations are sought in the form of linear combination of independent orthogonal functions {ψn(ζ)n=0∞} in the non-dimensional radial interval (0,1) and each orthogonal function is chosen to satisfy boundary conditions of adhesion at the solid walls of the channel. Under assumption that solutions of the equations are not oscillated rapidly according to radial coordinate r, finite numbers of orthogonal polynomials are considered. As a result, simultaneous equations with coefficients of steady-state solutions are arranged and dispersion relations between angular frequency and wave number of perturbed state are sought. The imaginary part of the angular frequency (wi) is taken into consideration from the condition of the existence of nontrivial solution of the system, which yields the relation between critical Reynolds number (Recr) and Hartmann number (Hα). In the present study, critical Reynolds number and Wave numbers are plotted on the Hartmann number for long wave perturbation, thus, it is shown that a magnetic field has a significant stabilizing effect on liquid metal flow. (author)

  11. Asymmetric flow field-flow fractionation of (bio) macromolecules (abstract)

    International Nuclear Information System (INIS)

    Field-Flow Fractionation (FFF) has developed into a promising separation technique with different variants in various applications fields of separation sciences. Asymmetric Flow FFF (FlFFF) is the most popular class of the FFF family; it is used for the separation and characterization of nano- to micro-sized particles of diverse origin. It is simple, gentle and soft separation principle is most feasible for fragile macromolecules present in biological samples. Although recently there has been a substantial involvement of asymmetric FlFFF for the characterization of proteins, viruses, DNA and cells, its application for body fluid analysis in clinical laboratories has yet to be explored. The purpose of the research study was to explore asymmetric FlFFF as an analytical tool for the analysis of (bio) macromolecules, especially in clinical perspective and to see how much the results based on its use are beneficent in diagnostic studies of various diseases. Different approaches involving asymmetric FlFFF prior to renowned separating techniques such as liquid and gas chromatography are exploited, to get additional insights in (bio) macromolecules based on their size. The research work was focused on human serum analysis, to characterize lipoproteins and their associated compounds, which could add more information in diagnosing coronary heart diseases. Furthermore, the size-based separation of blood circulating hyaluronan was studied, which could provide a vital clue in understanding the metabolic activity of endothelial glyco calyx under pathological conditions. (author)

  12. Augmentation of Real & Reactive Power in Grid by Unified Power Flow Controller

    Directory of Open Access Journals (Sweden)

    E.Rajasekar

    2016-05-01

    Full Text Available In this paper, a Power Flow Control in transmission line with respect to voltage condition (L-G, L-L-G, L-L over come by using unified power flow controller. The existing system employs UPFC with transformer less connection with both series and shunt converter. This converter have been cascaded with multilevel inverters which is more complicated to enhance the performance of UPFC.A proposed system consist of three terminal transformer for shunt converter and six terminal transformer for series converter. Shunt converter & series converter is coupled with common DC capacitor. DC link capacitor voltage is maintained using PID controller and synchronous reference frame theory (SRF is used to generate reference voltage & current signal. Simulation studies are carried out for (L-G, L-L-G, L-L real & reactive power compensation results will be shown in this paper.

  13. Transient Stability Augmentation by Programmed Power Angle Relationship using Unified Power Flow Controller

    OpenAIRE

    Padiyar, KR; Krishna, S

    2001-01-01

    Improvement in transient stability can be achieved by adequate system design and discrete supplementary controllers. The emerging Flexible AC Transmission System (FACTS) controllers are considered to be suitable for this purpose due to their speed and flexibility. The Unified Power Flow Controller (UPFC) is a voltage source converter based FACTS controller which injects a series voltage and a shunt current. In this paper, a control strategy is developed to achieve maximal improvement in trans...

  14. Magnetic field dissipation in converging flows

    International Nuclear Information System (INIS)

    Converging flows (e.g., gas accreting on to compact objects) are often ionized and magnetized. As the gas in these systems compresses towards smaller radii, flux conservation acts to intensify the magnetic field B, which can attain superequipartition values. (Throughout this paper, equipartition is meant to imply a comparison between the energy density in the field and that of the particles only, not including turbulence.) Since such a field probably cannot remain anchored in the gas, it is often assumed that the field intensity in excess of equipartition (i.e., Beq) is dissipated as heat, and that B therefore saturates at its Beq value -the so-called 'equipartition assumption'. In this paper we make an attempt at developing a model for magnetic field dissipation based on resistive magnetic tearing, in order to provide a more realistic means of determining the evolution of B in cases where the contribution to the spectrum from magnetic bremsstrahlung is important. We find that the violation of equipartition can vary in degree from large to small radii, and in either direction. Thus the spectrum predicted on the basis of the equipartition assumption is not always an adequate representation of the actual state of the system. However, several major shortcomings remain in our formulation. For example, our approach in this paper is to consider the turbulence as being initiated primarily by hydrodynamic processes. Arguing that the magnetic field is frozen into the highly ionized plasma, we therefore adopt a magnetic field spatial distribution that mirrors that of the gas. This may be valid Only when the field is subequipartition, for otherwise the turbulent cascade may be influenced primarily by magnetic dissipation, rather than the hydrodynamics

  15. Testing of SLA-561V in NASA-Ames' Turbulent Flow Duct with Augmented Radiative Heating

    Science.gov (United States)

    Sepka, Steven A.; Kornienko, Robert S.; Radbourne, Chris A.

    2010-01-01

    As part of Mars Science Laboratory s (MSL) heatshield development program, SLA-561 was tested in NASA Ames Turbulent Flow Duct (TFD) Facility. For these tests, the TFD facility was modified to include a ceramic plate located in the wall opposite to the test model. Normally the TFD wall opposite to the test model is water-cooled steel. Installing a noncooled ceramic plate allows the ceramic to absorb convective heating and radiate the energy back to the test model as the plate heats up. This work was an effort to increase the severity of TFD test conditions. Presented here are the results from these tests.

  16. Do You Believe in Magic? Exploring the Conceptualization of Augmented Reality and its Implications for the User in the Field of Library and Information Science

    OpenAIRE

    Zak, Elizabeth

    2014-01-01

    Augmented reality technology has implications for the ways that the field of library and information science (LIS) serves users and organizes information. Through content analysis, the author examined how augmented reality (AR) is conceptualized within a sample of LIS literature from the Library and Information Science and Technology Abstracts (LISTA) database and Google Blogs postings, and whether Radical Change Theory (RCT) and the digital age principles of interactivity, connectivity and a...

  17. Effectiveness of basic display augmentation in vehicular control by visual field cues

    Science.gov (United States)

    Grunwald, A. J.; Merhav, S. J.

    1978-01-01

    The paper investigates the effectiveness of different basic display augmentation concepts - fixed reticle, velocity vector, and predicted future vehicle path - for RPVs controlled by a vehicle-mounted TV camera. The task is lateral manual control of a low flying RPV along a straight reference line in the presence of random side gusts. The man-machine system and the visual interface are modeled as a linear time-invariant system. Minimization of a quadratic performance criterion is assumed to underlie the control strategy of a well-trained human operator. The solution for the optimal feedback matrix enables the explicit computation of the variances of lateral deviation and directional error of the vehicle and of the control force that are used as performance measures.

  18. Augmentation of Explicit Spatial Configurations by Knowledge-Based Inference on Geometric Fields

    Directory of Open Access Journals (Sweden)

    Dan Tappan

    2009-04-01

    Full Text Available A spatial configuration of a rudimentary, static, realworld scene with known objects (animals and properties (positions and orientations contains a wealth of syntactic and semantic spatial information that can contribute to a computational understanding far beyond what its quantitative details alone convey. This work presents an approach that (1 quantitatively represents what a configuration explicitly states, (2 integrates this information with implicit, commonsense background knowledge of its objects and properties, (3 infers additional, contextually appropriate, commonsense spatial information from and about their interrelationships, and (4 augments the original representation with this combined information. A semantic network represents explicit, quantitative information in a configuration. An inheritance-based knowledge base of relevant concepts supplies implicit, qualitative background knowledge to support semantic interpretation. Together, these structures provide a simple, nondeductive, constraint-based, geometric logical formalism to infer substantial implicit knowledge for intrinsic and deictic frames of spatial reference.

  19. Heat transfer augmentation of a circular pipe flow using nano-particle layers

    Energy Technology Data Exchange (ETDEWEB)

    Yamagishi, Akira; Yuki, Kazuhisa; Sato, Tomoaki; Hashizume, Hidetoshi [Tohoku Univ. (Japan). Dept. of Quantum Science and Energy Engineering; Kunugi, Tomoaki [Kyoto Univ. (Japan). Faculty of Engineering; Sagara, Akio [National Inst. for Fusion Science (Japan)

    2007-07-01

    For the advanced fusion reactor FFHR2 (Force Free Helical Reactor) that has been proposed by NIFS, molten salt Flibe (LiF:BeF2=64:36) breeder blanket system is selected because of Flibe's features such as chemical stability, low-pressure operation and low electric conductivity. The Flibe is however high Prandtl number fluid since it has high viscosity and low thermal conductivity. Therefore its heat transfer performance is low compared with liquid Li or Pb-Li. In addition to heat removal of 1MW/m2 on the first wall, electrolysis of molten salt due to MHD effect will take place under high flow rate condition. This indicates that heat transfer enhancement under low flow rate is essential for the Flibe blanket system. In our laboratory, heat transfer characteristics of molten salt HTS (KNO3:NaNO2:NaNO3=53:40:7), have been evaluated, which is used as a simulant fluid of Flibe from the points of view of Be's toxicity and similar Prandtl number. In this paper, we adopt nano-particle layer method to form nano{proportional_to}micro scale structure on a heating surface using an acid or an alkali includes nano particles. There exist two methods to form nano particle layer. One is NPLS (Nano Particle Layer Structure) method which uses a chemical etching with an acid or an alkali including copper-oxide nano-particles. The other is FP (Fine Particle) method which employs electroless plating with inorganic metal salt solution. At first, immersion experiments of NPLS or FP layers into melted HTS shows that erosion of the FP sample is much less than that of the NPLS sample. Furthermore, a forced-convention heat transfer experiments with a circular tube whose inner surface has the nano-particle layer by the FP method is carried out in a large molten salt circulating loop named as TNT loop. Results show that average Nusselt numbers of the circular tube flow are about 1.3 times higher than that of a bared tube in the range of 3000

  20. Effect of front guide nozzle shape on the flow characteristics in an augmentation channel of a direct drive turbine for wave power generation

    Institute of Scientific and Technical Information of China (English)

    Deepak; PRASAD; Mohammed; Asid; ZULLAH; Mohammed; Rafiuddin; AHMED; Young-Ho; LEE

    2010-01-01

    There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work aims at implementing the direct drive turbine(DDT) of cross flow type for wave power generation.A numerical wave tank was used to simulate the waves and after obtaining the desired wave properties;the augmentation channel plus the front guide nozzle and rear chamber were integrated to the numerical wave tank.The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet.The inlet which was modeled as a plate wall moved sinusoidally with the general function x = asinω t.The augmentation channel consisted of a front nozzle,rear nozzle and an internal fluid region which represented the turbine housing.The front and rear nozzles were geometrically the same.Three different front guide nozzle configurations were studied:a standard guide nozzle which was originally attached to the augmentation channel and two other front guide nozzles of different geometries.The purpose of this study is to observe how the front guide nozzle shape influences the flow downstream,mainly in the augmenta-tion channel,water power and the first stage energy conversion.The analysis was performed using a commercial CFD code ANSYS-CFX.The results of the flow in the augmentation channel for the three front guide nozzles are presented in this paper.

  1. Performance of a vanadium redox flow battery with and without flow fields

    International Nuclear Information System (INIS)

    Highlights: • The performances of a VRFB with/without flow fields are compared. • The respective maximum power efficiency occurs at different flow rates. • The battery with flow fields Exhibits 5% higher energy efficiency. - Abstract: A flow field is an indispensable component for fuel cells to macroscopically distribute reactants onto electrodes. However, it is still unknown whether flow fields are also required in all-vanadium redox flow batteries (VRFBs). In this work, the performance of a VRFB with flow fields is analyzed and compared with the performance of a VRFB without flow fields. It is demonstrated that the battery with flow fields has a higher discharge voltage at higher flow rates, but exhibits a larger pressure drop. The maximum power-based efficiency occurs at different flow rates for the both batteries with and without flow fields. It is found that the battery with flow fields Exhibits 5% higher energy efficiency than the battery without flow fields, when operating at the flow rates corresponding to each battery's maximum power-based efficiency. Therefore, the inclusion of flow fields in VRFBs can be an effective approach for improving system efficiency

  2. Augmented postcard

    OpenAIRE

    Bernik , Aleš

    2012-01-01

    The aim of this thesis is the examination of augmented reality technology, which allows us mixing real and virtual elements. Augmented reality is a relatively new technology which is becoming more widespread, thanks to a fairly reasonable price of smart phones. Here we presents the types of augmented reality, the necessary technology and their advantages and disadvantages, its current use in applications, and software for building augmented reality applications. The thesis is mainly focuse...

  3. Monodisperse granular flows in viscous dispersions in a centrifugal acceleration field

    Science.gov (United States)

    Cabrera, Miguel Angel; Wu, Wei

    2016-04-01

    Granular flows are encountered in geophysical flows and innumerable industrial applications with particulate materials. When mixed with a fluid, a complex network of interactions between the particle- and fluid-phase develops, resulting in a compound material with a yet unclear physical behaviour. In the study of granular suspensions mixed with a viscous dispersion, the scaling of the stress-strain characteristics of the fluid phase needs to account for the level of inertia developed in experiments. However, the required model dimensions and amount of material becomes a main limitation for their study. In recent years, centrifuge modelling has been presented as an alternative for the study of particle-fluid flows in a reduced scaled model in an augmented acceleration field. By formulating simple scaling principles proportional to the equivalent acceleration Ng in the model, the resultant flows share many similarities with field events. In this work we study the scaling principles of the fluid phase and its effects on the flow of granular suspensions. We focus on the dense flow of a monodisperse granular suspension mixed with a viscous fluid phase, flowing down an inclined plane and being driven by a centrifugal acceleration field. The scaled model allows the continuous monitoring of the flow heights, velocity fields, basal pressure and mass flow rates at different Ng levels. The experiments successfully identify the effects of scaling the plastic viscosity of the fluid phase, its relation with the deposition of particles over the inclined plane, and allows formulating a discussion on the suitability of simulating particle-fluid flows in a centrifugal acceleration field.

  4. Water Modeling of Optimizing Tundish Flow Field

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-gang; YAN Hui-cheng; LIU Liu; WANG Xin-hua

    2007-01-01

    In the water modeling experiments, three cases were considered, i.e. , a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs (dams) and a turbulence inhibitor. Comparing the RTD curves, inclusion separation, and the result of the streamline experiment, it can be found that the tundish equipped with weirs (dams) and a turbulence inhibitor has a great effect on the flow field and the inclusion separation when compared with the sole use or no use of the turbulent inhibitor or weirs (dams). In addition, the enlargement of the distance between the weir and dam will result in a better effect when the tundish equipped with weirs (dam) and a turbulence inhibitor was used.

  5. Calculation and measurement of horizontal flow fields in tidal rivers

    International Nuclear Information System (INIS)

    A new technique for horizontal flow measurements in tidal rivers by the moving boat method is described. A two-dimensional tidal model for shallow waters using measured velocity cross-profiles on the open boundaries is developed. The flow field of the lower Weser river is calculated and comparisons of numerical results with measured field data are performed. The influence of model parameters on the calculated flow fields is discussed. (orig.)

  6. AC Electric Fields Drive Steady Flows in Flames

    OpenAIRE

    Drews, Aaron M.; Cademartiri, Ludovico; Chemama, Michael Leopold; Brenner, Michael P.; Whitesides, George M.; Bishop, Kyle J. M.

    2012-01-01

    We show that time-oscillating electric fields applied to plasmas present in flames create steady flows of gas. Ions generated within the flame move in the field and migrate a distance δ before recombining; the net flow of ions away from the flame creates a time-averaged force that drives the steady flows observed experimentally. A quantitative model describes the response of the flame and reveals how δ decreases as the frequency of the applied field increases. Interestingly, above a critical ...

  7. Magnetohydrodynamic channel flows with weak transverse magnetic fields.

    Science.gov (United States)

    Rothmayer, A P

    2014-07-28

    Magnetohydrodynamic flow of an incompressible fluid through a plane channel with slowly varying walls and a magnetic field applied transverse to the channel is investigated in the high Reynolds number limit. It is found that the magnetic field can first influence the hydrodynamic flow when the Hartmann number reaches a sufficiently large value. The magnetic field is found to suppress the steady and unsteady viscous flow near the channel walls unless the wall shapes become large. PMID:24936018

  8. A 2-year follow-up study of patients participating in our transcranial pulsating electromagnetic fields augmentation in treatment-resistant depression

    DEFF Research Database (Denmark)

    Bech, Per; Lindberg, Lone; Straasø, Birgit;

    2015-01-01

    OBJECTIVE: We have made a 2-year follow-up study to evaluate the effect of repeated transcranial pulsating electromagnetic fields (T-PEMF) augmentation in patients who had achieved remission but later on relapsed, as well as to identify factors contributing to treatment-resistant depression in...... first series of T-PEMF. Treatment-resistant depression is a condition that has a high degree of multivariate problems. Misuse of alcohol or drugs, severe somatic disorders and other psychosocial problems may need other kinds of treatment before T-PEMF augmentation....

  9. Effect of an electric field on an intermittent granular flow

    OpenAIRE

    Mersch, E.; Lumay, G.; F. Boschini; Vandewalle, N.

    2010-01-01

    Granular gravity driven flows of glass beads have been observed in a silo with a flat bottom. A DC high electric field has been applied perpendicularly to the silo to tune the cohesion. The outlet mass flow has been measured. An image subtraction technique has been applied to visualize the flow geometry and a spatiotemporal analysis of the flow dynamics has been performed. The outlet mass flow is independent of voltage, but a transition from funnel flow to rathole flow is observed. This trans...

  10. Low magnetic fields for flow propagators in permeable rocks.

    Science.gov (United States)

    Singer, Philip M; Leu, Gabriela; Fordham, Edmund J; Sen, Pabitra N

    2006-12-01

    Pulsed field gradient NMR flow propagators for water flow in Bentheimer sandstone are measured at low fields (1H resonance 2 MHz), using both unipolar and bipolar variants of the pulsed gradient method. We compare with propagators measured at high fields (1H resonance 85 MHz). We show that (i) measured flow propagators appear to be equivalent, in this rock, and (ii) the lower signal to noise ratio at low fields is not a serious limitation. By comparing different pulse sequences, we study the effects of the internal gradients on the propagator measurement at 2 MHz, which for certain rocks may persist even at low fields. PMID:16962343

  11. Flow equations for supersymmetric field theories

    International Nuclear Information System (INIS)

    A manifestly supersymmetric exact renormalization group flow is presented for the N=1 Wess-Zumino-Model in two dimensions. For that purpose, supersymmetric regulators are constructed in the off-shell formulation. The considered model allows for dynamical supersymmetry breaking. The phase diagramm is discussed as well as the fixed-point structure of the ERG-flow

  12. Reconstruction of velocity fields in electromagnetic flow tomography.

    Science.gov (United States)

    Lehtikangas, Ossi; Karhunen, Kimmo; Vauhkonen, Marko

    2016-06-28

    Electromagnetic flow meters (EMFMs) are the gold standard in measuring flow velocity in process industry. The flow meters can measure the mean flow velocity of conductive liquids and slurries. A drawback of this approach is that the velocity field cannot be determined. Asymmetric axial flows, often encountered in multiphase flows, pipe elbows and T-junctions, are problematic and can lead to serious systematic errors. Recently, electromagnetic flow tomography (EMFT) has been proposed for measuring velocity fields using several coils and a set of electrodes attached to the surface of the pipe. In this work, a velocity field reconstruction method for EMFT is proposed. The method uses a previously developed finite-element-based computational forward model for computing boundary voltages and a Bayesian framework for inverse problems. In the approach, the vz-component of the velocity field along the longitudinal axis of the pipe is estimated on the pipe cross section. Different asymmetric velocity fields encountered near pipe elbows, solids-in-water flows in inclined pipes and in stratified or multiphase flows are tested. The results suggest that the proposed reconstruction method could be used to estimate velocity fields in complicated pipe flows in which the conventional EMFMs have limited accuracy. This article is part of the themed issue 'Supersensing through industrial process tomography'. PMID:27185961

  13. NUMERICAL SIMULATION OF FLOW FIELD INSIDE HYDRAULIC SPOOL VALVE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The finite element method of computational fluid dynamics was applied to simulate the internal flow field in hydraulic spool valve which is one of the most important components in hydraulic technique. The formation of the vortexes with time was investigated under two different flow conditions. Two kinds of flow descriptions including streamline patterns and velocity vector plots were given to show the flow field inside the spool valve clearly, which is of theoretical significance and of practical values to analyze energy loss and fluid noise in the valve and to optimize the intermal flow structure of the valve.

  14. Energy flow structuring in the focused field

    CERN Document Server

    Chen, Hao

    2015-01-01

    We propose an iterative method of energy flow shaping in the focal region with the amplitude, phase and polarization modulation of incident light. By using an iterative optimization based on the diffraction calculation with help of the fast Fourier transform, we can tailor the polarization and phase structure in the focal plane. By appropriate design of the polarization and phase gradients, arbitrary energy flow including spin and orbital parts can be designed and tailored independently. The capability of energy flow structuring is demonstrated by the measurement of the Stokes parameters and self-interference pattern. This provides a novel method to control the vectorial feature of the focal volume.

  15. Energy flow structuring in the focused field

    OpenAIRE

    Chen, Hao; Li, Guoqiang

    2015-01-01

    We propose an iterative method of energy flow shaping in the focal region with the amplitude, phase and polarization modulation of incident light. By using an iterative optimization based on the diffraction calculation with help of the fast Fourier transform, we can tailor the polarization and phase structure in the focal plane. By appropriate design of the polarization and phase gradients, arbitrary energy flow including spin and orbital parts can be designed and tailored independently. The ...

  16. Computational analysis of the flow field downstream of flow conditioners

    Energy Technology Data Exchange (ETDEWEB)

    Erdal, Asbjoern

    1997-12-31

    Technological innovations are essential for maintaining the competitiveness for the gas companies and here metering technology is one important area. This thesis shows that computational fluid dynamic techniques can be a valuable tool for examination of several parameters that may affect the performance of a flow conditioner (FC). Previous design methods, such as screen theory, could not provide fundamental understanding of how a FC works. The thesis shows, among other things, that the flow pattern through a complex geometry, like a 19-hole plate FC, can be simulated with good accuracy by a k-{epsilon} turbulence model. The calculations illuminate how variations in pressure drop, overall porosity, grading of porosity across the cross-section and the number of holes affects the performance of FCs. These questions have been studied experimentally by researchers for a long time. Now an understanding of the important mechanisms behind efficient FCs emerges from the predictions. 179 ref., 110 figs., 8 tabs.

  17. Biofilm responses to smooth flow fields and chemical gradients in novel microfluidic flow cells

    OpenAIRE

    Song, Jisun L.; Au, Kelly H.; Huynh, Kimberly T.; Packman, Aaron I.

    2013-01-01

    We present two novel microfluidic flow cells developed to provide reliable control of flow distributions and chemical gradients in biofilm studies. We developed a single-inlet microfluidic flow cell to support biofilm growth under a uniform velocity field, and a double-inlet flow cell to provide a very smooth transverse concentration gradient. Both flow cells consist of a layer of polydimethylsiloxane (PDMS) bonded to glass cover slips and were fabricated using the replica molding technique. ...

  18. Geology of the Tyrrhenus Mons Lava Flow Field, Mars

    Science.gov (United States)

    Crown, David A.; Mest, Scott C.

    2014-11-01

    The ancient, eroded Martian volcano Tyrrhenus Mons exhibits a central caldera complex, layered flank deposits dissected by radial valleys, and a 1000+ km-long flow field extending to the southwest toward Hellas Planitia. Past studies suggested an early phase of volcanism dominated by large explosive eruptions followed by subsequent effusive activity at the summit and to the southwest. As part of a new geologic mapping study of northeast Hellas, we are examining the volcanic landforms and geologic evolution of the Tyrrhenus Mons flow field, including the timing and nature of fluvial activity and effects on volcanic units. New digital geologic mapping incorporates THEMIS IR (100 m/pixel) and CTX (5 m/pixel) images as well as constraints from MOLA topography.Mapping results to-date include delineation of the boundaries of the flow field, identification and mapping of volcanic and erosional channels within the flow field, and mapping and analysis of lava flow lobes. THEMIS IR and CTX images allow improved discrimination of the numerous flow lobes that are observed in the flow field, including refinement of the margins of previously known flows and identification of additional and smaller lobes. A prominent sinuous rille extending from Tyrrhenus Mons’ summit caldera is a major feature that supplied lava to the flow field. Smaller volcanic channels are common throughout the flow field; some occur in segments along crests of local topographic highs and may delineate lava tubes. In addition to volcanic channels, the flow field surface is characterized by several types of erosional channels, including wide troughs with scour marks, elongate sinuous channels, and discontinuous chains of elongate pits and troughs. High-resolution images reveal the widespread and significant effects of fluvial activity in the region, and further mapping studies will examine spatial and temporal interactions between volcanism and fluvial processes.

  19. PIV MEASUREMENTS FOR GAS FLOW UNDER GRADIENT MAGNETIC FIELDS

    Institute of Scientific and Technical Information of China (English)

    RUAN Xiaodong; WU Feng; F.YAMAMOTO

    2004-01-01

    Particle Image Velocimetry (PIV) techniques were developed to measure the convective N2-air flow under gradient magnetic fields. The velocity fields were calculated by the Minimum Quadratic Difference (MQD) algorithm and spurious vectors were eliminated by Delaunay Tessellation.The N2-air flow was measured as the magnetic flux density varying from 0 ~ 1.5 T. A strengthened vortex flow of air was observed under the condition that the magnetic field was applied, and the velocity of N2 jet rose with the increase of the magnetic density. The experimental results show that the magnetic force will induce a vortex flow and cause a convection flow of the air mixture when both gradients of the O2 concentration and the magnetic field intensity exist.

  20. Variability modes in core flows inverted from geomagnetic field models

    CERN Document Server

    Pais, Maria A; Schaeffer, Nathanaël

    2014-01-01

    We use flows that we invert from two geomagnetic field models spanning centennial time periods (gufm1 and COV-OBS), and apply Principal Component Analysis and Singular Value Decomposition of coupled fields to extract the main modes characterizing their spatial and temporal variations. The quasi geostrophic flows inverted from both geomagnetic field models show similar features. However, COV-OBS has a less energetic mean flow and larger time variability. The statistical significance of flow components is tested from analyses performed on subareas of the whole domain. Bootstrapping methods are also used to extract robust flow features required by both gufm1 and COV-OBS. Three main empirical circulation modes emerge, simultaneously constrained by both geomagnetic field models and expected to be robust against the particular a priori used to build them. Mode 1 exhibits three large robust vortices at medium/high latitudes, with opposite circulation under the Atlantic and the Pacific hemispheres. Mode 2 interesting...

  1. Flow Field of an Exited Impinging Jet

    Czech Academy of Sciences Publication Activity Database

    Vejražka, Jiří; Marty, P.; Tihon, Jaroslav

    Aachen, 2002, s. 29-31. [Workshop Local Flow Effects in Hydrodynamic Systems /2./. Aachen (DE), 07.11.2002-09.11.2002] R&D Projects: GA MŠk OC F2.10 Keywords : impinging jet * vortex structure * phase averaging technique Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  2. Compression and Cavitation of Externally Applied Magnetic Field on a Hohlraum due to Non-Local Heat Flow Effects

    Science.gov (United States)

    Joglekar, Archis; Thomas, Alec; Ridgers, Chris; Kingham, Rob

    2015-11-01

    In this study, we present full-scale 2D kinetic modeling of externally imposed magnetic fields on hohlraums with laser heating. We observe magnetic field cavitation and compression due to thermal energy transport. Self-consistent modeling of the electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's Law. A complete Ohm's Law contains magnetic field advection through the Nernst mechanism that arises due to the heat flow. Magnetic field amplification by a factor of 3 occurs due to magnetic flux pile-up from Nernst convection. The magnetic field cavitates towards the hohlraum axis over a 0.5 ns time scale due to Nernst convection. This results in significantly different magnetic field profiles and slower cavitation than can be expected due to the plasma bulk flow. Non-local electrons contribute to the heat flow down the density gradient resulting in an augmented Nernst convection mechanism that is included self-consistently through kinetic modeling. In addition to showing the prevalence of non-local heat flows, we show effects such as anomalous heat flow up the density gradient induced by inverse bremsstrahlung heating. This research was supported by the DOE through Grant No. DE SC0010621 and in part through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor.

  3. Nonintrusive flow field measurements (using laser Raman spectroscopy)

    International Nuclear Information System (INIS)

    Nonintrusive flow field measurements have received great attention, where the presence of a physical probe would cause an unacceptable pertubation to the system under study. There is a continuing need for the noninterfering measurement of gas temperature and number density in high speed flow fields, turbulent mixing, reaction kinetic, environmental pollution and so on. Molecular Raman scattering is well suited to obtain local measurements of individual gas densities and gas temperatures. In this report the main effort has involved experimental and analytical procedures necessary to determine these flow field parameters. The study was concerned with the applications of a single pulse technique to the diagnostics. (orig.)

  4. Estimation of Dense Image Flow Fields in Fluids

    OpenAIRE

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    1995-01-01

    The estimation of flow fields from time sequences of satellite imagery has a number of important applications. For visualisation of cloud or sea ice movements in sequences of crude temporal sampling a satisfactory non-blurred temporal interpolation can be performed only when the flow field or an estimate there-of is known. Estimated flow fields in weather satellite imagery might also be used on an operational basis as inputs to short-term weather prediction. In this article we describe a meth...

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

    DEFF Research Database (Denmark)

    Finlay, Chris; Amit, H.

    We present a method to estimate the typical magnitude of flow close toEarth's core surface based on observational knowledge of the maingeomagnetic field (MF) and its secular variation (SV), together withprior information concerning field-flow alignment gleaned from numericaldynamo models. An expr...

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

    Science.gov (United States)

    Finlay, C. C.; Amit, H.

    2012-12-01

    We present a method to estimate the typical magnitude of flow close to Earth's core surface based on observational knowledge of the main geomagnetic field (MF) and its secular variation (SV), together with prior information concerning field-flow alignment gleaned from numerical dynamo models. An expression linking the core surface flow magnitude to spherical harmonic spectra of the MF and SV is derived from the magnetic induction equation. This involves the angle γ between the flow and the horizontal gradient of the radial field. We study γ in a suite of numerical dynamo models and discuss the physical mechanisms that control it. Horizontal flow is observed to approximately follow contours of the radial field close to high-latitude flux bundles, while more efficient induction occurs at lower latitudes where predominantly zonal flows are often perpendicular to contours of the radial field. We show that the amount of field-flow alignment depends primarily on a magnetic modified Rayleigh number Raη = α g0 Δ T D / η Ω , which measures the vigor of convective driving relative to the strength of magnetic dissipation. Synthetic tests of the flow magnitude estimation scheme are encouraging, with results differing from reference values by less than 8%. Application to a high quality geomagnetic field model based on satellite observations (the xCHAOS model in epoch 2004.0) leads to a flow magnitude estimate of 11 - 14 km / yr, in accordance with previous estimates. When applied to the historical geomagnetic field model gufm1 for the interval 1840.0 - 1990.0, the method predicts temporal variations in flow magnitude similar to those found in earlier studies. The calculations rely primarily on knowledge of the MF and SV spectra; by extrapolating these beyond observed scales the influence of small scales on flow magnitude estimates is assessed. Exploring three possible spectral extrapolations we find that the magnitude of the core surface flow, including small scales, is

  7. Numerical simulation of flow fields and particle trajectories

    DEFF Research Database (Denmark)

    Mayer, Stefan

    2000-01-01

    A model describing the ciliary driven flow and motion of suspended particles in downstream suspension feeders is developed. The quasi-steady Stokes equations for creeping flow are solved numerically in an unbounded fluid domain around cylindrical bodies using a boundary integral formulation. The...... time-dependent flow is approximated with a continuous sequence of steady state creeping flow fields, where metachronously beating ciliary bands are modelled by linear combinations of singularity solutions to the Stokes equations. Generally, the computed flow fields can be divided into an unsteady...... the simulated unsteady ciliary driven flow. A fraction of particles appear to follow trajectories, that resemble experimentally observed particle capture events in the downstream feeding system of the polycheate Sabella penicillus, indicating that particles can be captured by ciliary systems without...

  8. Rendering methods for augmented reality

    OpenAIRE

    Fischer, Jan

    2006-01-01

    Augmented reality (AR) has become a promising and fast-growing application of computer graphics over the course of the last years. Augmented reality systems overlay computer-generated graphical information over the view of the real world. Several main research challenges can be identified in the field of augmented reality. These are the design of advanced display devices (e.g., head-mounted displays), camera tracking, system design, user interaction, and rendering. While a major part of the p...

  9. Effect of flow field on the performance of an all-vanadium redox flow battery

    Science.gov (United States)

    Kumar, S.; Jayanti, S.

    2016-03-01

    A comparative study of the electrochemical energy conversion performance of a single-cell all-vanadium redox flow battery (VRFB) fitted with three flow fields has been carried out experimentally. The charge-discharge, polarization curve, Coulombic, voltage and round-trip efficiencies of a 100 cm2 active area VRFB fitted with serpentine, interdigitated and conventional flow fields have been obtained under nearly identical experimental conditions. The effect of electrolyte circulation rate has also been investigated for each flow field. Stable performance has been obtained for each flow field for at least 40 charge/discharge cycles. Ex-situ measurements of pressure drop have been carried out using water over a range of Reynolds numbers. Together, the results show that the cell fitted with the serpentine flow field gives the highest energy efficiency, primarily due to high voltaic efficiency and also the lowest pressure drop. The electrolyte flow rate is seen to have considerable effect on the performance; a high round-trip energy efficiency of about 80% has been obtained at the highest flow rate with the serpentine flow field. The data offer interesting insights into the effect of electrolyte circulation on the performance of VRFB.

  10. Specific Properties of Air Flow Field Within the Grinding Zone

    Institute of Scientific and Technical Information of China (English)

    ZHENG Junyi; JIANG Zhengfeng; ZHAO Liang

    2006-01-01

    Air barrier of grinding means a boundary layer of air existing at the circumference of the rotating wheel, which hinders coolant from entry. This paper makes a research on air flow field of the grinding zone through experiments and numerical simulations, focusing on acquainting with the specific properties of the air flow field. Finite volume method is applied to analyze air flow field within grinding wheel in the course of numerical calculations. The test devices such as Hot-wire anemometer and Betz manometer are used during the experiments of testing the pressure and velocity within grinding zone. Results of experiments agree by and large with numerical results of calculations. The conclusions obtained in this paper, the distribution of wall pressure and the distribution of air flow velocity, are important and useful to navigate the delivery of coolant into the grinding zone. In conclusion, some recommendations are made for further study and practical applications in such field.

  11. Lip augmentation.

    Science.gov (United States)

    Byrne, Patrick J; Hilger, Peter A

    2004-02-01

    Lip augmentation has become increasingly popular in recent years as a reflection of cultural trends emphasizing youth and beauty. Techniques to enhance the appearance of the lips have evolved with advances in biotechnology. An understanding of lip anatomy and aesthetics forms the basis for successful results. We outline the pertinent anatomy and aesthetics of the preoperative evaluation. A summary of various filler materials available is provided. Augmentation options include both injectable and open surgical techniques. The procedures and materials currently favored by the authors are described in greater detail. PMID:15034811

  12. Magnetohydrodynamic cross-field boundary layer flow

    Directory of Open Access Journals (Sweden)

    D. B. Ingham

    1982-01-01

    Full Text Available The Blasius boundary layer on a flat plate in the presence of a constant ambient magnetic field is examined. A numerical integration of the MHD boundary layer equations from the leading edge is presented showing how the asymptotic solution described by Sears is approached.

  13. Uncertainty in multiphase flow estimates for a field development case

    OpenAIRE

    Bjørlo, Ingvil

    2013-01-01

    Commercial multiphase flow simulators typically give one value for each output parameter simulated in a pipeline. Field development project managers want to know the uncertainty in these predictions in order to assess the risk. A study on two field cases, one gravity dominated case and one friction dominated, from the Troll P10 pipeline was conducted using the multiphase flow simulator OLGA and the functions in the embedded RMO (Risk Management and Optimization) module. A sensitivity analysis...

  14. Augmentation of laminar flow and heat transfer in flat tubes by means of helical screw-tape inserts

    International Nuclear Information System (INIS)

    The heat transfer a characteristics and friction factor in the horizontal double pipes of flat tubes with full length helical screw element of different twist ratio and helical screw inserts with different spacer length are investigated. Cold and hot water are used as working fluid in tube side and shell side respectively. The experiments covered a range of Reynolds numbers 5.7 x 102 ≤ Re ≤ 1.31 x 103. The effect of spacer length on the heat transfer augmentation and friction factor and the effect of twist ratio on heat transfer augmentation and friction factor have been presented separately. The study shows that, the Nusslet number (Nu) and friction factor (f) decrease with the increase of S or Y for flat tube. The comparison between the data of present plain circular with that of previous plain circular tube showed a good agreement between them but the data of present plain flat tube showed a higher in heat transfer and pressure drop than that of plain circular tube. The correlations of average Nusselt number and friction factor with Re, S and Y are presented.

  15. Augmentation of laminar flow and heat transfer in flat tubes by means of helical screw-tape inserts

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, E.Z., E-mail: emadz20022000@yahoo.co [Faculty of Engineering, Zagazig University, 44519 Zagazig (Egypt)

    2011-01-15

    The heat transfer a characteristics and friction factor in the horizontal double pipes of flat tubes with full length helical screw element of different twist ratio and helical screw inserts with different spacer length are investigated. Cold and hot water are used as working fluid in tube side and shell side respectively. The experiments covered a range of Reynolds numbers 5.7 x 10{sup 2} {<=} Re {<=} 1.31 x 10{sup 3}. The effect of spacer length on the heat transfer augmentation and friction factor and the effect of twist ratio on heat transfer augmentation and friction factor have been presented separately. The study shows that, the Nusslet number (Nu) and friction factor (f) decrease with the increase of S or Y for flat tube. The comparison between the data of present plain circular with that of previous plain circular tube showed a good agreement between them but the data of present plain flat tube showed a higher in heat transfer and pressure drop than that of plain circular tube. The correlations of average Nusselt number and friction factor with Re, S and Y are presented.

  16. Augmented Reality

    DEFF Research Database (Denmark)

    Kjærgaard, Hanne Wacher; Kjeldsen, Lars Peter Bech; Rahn, Annette

    2015-01-01

    This chapter describes the use of iPad-facilitated application of augmented reality in the teaching of highly complex anatomical and physiological subjects in the training of nurses at undergraduate level. The general aim of the project is to investigate the potentials of this application in term...

  17. Polymer electrolyte fuel cells: flow field for efficient air operation

    Energy Technology Data Exchange (ETDEWEB)

    Buechi, F.N.; Tsukada, A.; Haas, O.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    A new flow field was designed for a polymer electrolyte fuel cell stack with an active area of 200 cm{sup 2} for operation at low air stoichiometry and low air over pressure. Optimum of gas flow and channel dimensions were calculated based on the required pressure drop in the fluid. Single cells and a bi-cell stack with the new flow field show an improved current/voltage characteristic when operated at low air stoichiometries as compared to that of the previous non optimized design. (author) 4 figs., 3 refs.

  18. Propulsion efficiency and imposed flow fields of a copepod jump

    DEFF Research Database (Denmark)

    Jiang, H.; Kiørboe, Thomas

    2011-01-01

    imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simulations by modeling the copepod as a self-propelled body. The computational fluid dynamics simulation was validated by particle image velocimetry data. The flow field generated by a repositioning jump...... quickly evolves into two counter-rotating viscous vortex rings that are near mirror image of one another, one in the wake and one around the body of the copepod; this near symmetrical flow may provide hydrodynamic camouflage because it contains no information about the position of the copepod prey within...

  19. On the flow field around a Savonius rotor

    Science.gov (United States)

    Bergeles, G.; Athanassiadis, N.

    A model of a two-bucket Savonius rotor windmill was constructed and tested in a wind tunnel. The flow field around the rotor was examined visually and also quantitatively with the use of a hot wire. The flow visualization revealed an upstream influence on the flow field up to 3 rotor diameters away and a strong downwash downstream. Hot wire measurements showed a large velocity deficit behind the rotor and a quick velocity recovery downstream due to strong mixing; the latter was associated with high levels of turbulence. Energy spectra revealed that all turbulence was concentrated in a single harmonic corresponding to twice the rotational speed of the rotor.

  20. Computation of flow pressure fields from magnetic resonance velocity mapping.

    Science.gov (United States)

    Yang, G Z; Kilner, P J; Wood, N B; Underwood, S R; Firmin, D N

    1996-10-01

    Magnetic resonance phase velocity mapping has unrivalled capacities for acquiring in vivo multi-directional blood flow information. In this study, the authors set out to derive both spatial and temporal components of acceleration, and hence differences of pressure in a flow field using cine magnetic resonance velocity data. An efficient numerical algorithm based on the Navier-Stokes equations for incompressible Newtonian fluid was used. The computational approach was validated with in vitro flow phantoms. This work aims to contribute to a better understanding of cardiovascular dynamics and to serve as a basis for investigating pulsatile pressure/flow relationships associated with normal and impaired cardiovascular function. PMID:8892202

  1. Flows and chemical reactions in an electromagnetic field

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions', 'Chemical Reactions Flows in Homogeneous Mixtures' and 'Chemical Reactions and Flows in Heterogeneous Mixtures' - is devoted to flows with chemical reactions in the electromagnetic field. The first part, entitled basic equations, consists of four chapters. The first chapter provides an overview of the equations of electromagnetism in Minkowski spacetime. This presentation is extended to balance equations, first in homogeneous media unpolarized in the second chapter and homogeneous fluid medium polarized in the thir

  2. Numerical Simulations of Canted Nozzle and Scarfed Nozzle Flow Fields

    Science.gov (United States)

    Javed, Afroz; Chakraborty, Debasis

    2016-06-01

    Computational fluid dynamics (CFD) techniques are used for the analysis of issues concerning non-conventional (canted and scarfed) nozzle flow fields. Numerical simulations are carried out for the quality of flow in terms of axisymmetric nature at the inlet of canted nozzles of a rocket motor. Two different nozzle geometries are examined. The analysis of these simulation results shows that the flow field at the entry of the nozzles is non axisymmetric at the start of the motor. With time this asymmetry diminishes, also the flow becomes symmetric before the nozzle throat, indicating no misalignment of thrust vector with the nozzle axis. The qualitative flow fields at the inlet of the nozzles are used in selecting the geometry with lesser flow asymmetry. Further CFD methodology is used to analyse flow field of a scarfed nozzle for the evaluation of thrust developed and its direction. This work demonstrates the capability of the CFD based methods for the nozzle analysis problems which were earlier solved only approximately by making simplifying assumptions and semi empirical methods.

  3. Using Animated Textures to Visualize Electromagnetic Fields and Energy Flow

    CERN Document Server

    Belcher, John

    2008-01-01

    Animated textures can be used to visualize the spatial structure and temporal evolution of vector fields at high spatial resolution. The animation requires two time-dependent vector fields. The first of these vector fields determines the spatial structure to be displayed. The second is a velocity field that determines the time evolution of the field lines of the first vector field. We illustrate this method with an example in magneto-quasi-statics, where the second velocity field is taken to be the ExB drift velocity of electric monopoles. This technique for displaying time-dependent electromagnetic fields has three pedagogical advantages: (1) the continuous nature of the representation underscores the action-by-contact nature of forces transmitted by fields; (2) the animated texture motion shows the direction of electromagnetic energy flow; and (3) the time-evolving field configuration enables insights into Maxwell stresses.

  4. Flow Field Evolution of a Decaying Sunspot

    CERN Document Server

    Deng, Na; Tritschler, Alexandra; Denker, Carsten; Liu, Chang; Wang, Haimin

    2007-01-01

    We study the evolution of the flows and horizontal proper motions in and around a decaying follower sunspot based on time sequences of two-dimensional spectroscopic observations in the visible and white light imaging data obtained over six days from June~7 to~12, 2005. During this time period the sunspot decayed gradually to a pore. The spectroscopic observations were obtained with the Fabry-P\\'{e}rot based Visible-Light Imaging Magnetograph (VIM) in conjunction with the high-order adaptive optics (AO) system operated at the 65 cm vacuum reflector of the Big Bear Solar Observatory (BBSO). We apply local correlation tracking (LCT) to the speckle reconstructed time sequences of white-light images around 600 nm to infer horizontal proper motions while the Doppler shifts of the scanned \\FeI line at 630.15 nm are used to calculate line-of-sight (LOS) velocities with sub-arcsecond resolution. We find that the dividing line between radial inward and outward proper motions in the inner and outer penumbra, respectivel...

  5. Pedestrian Flow in the Mean Field Limit

    KAUST Repository

    Haji Ali, Abdul Lateef

    2012-11-01

    We study the mean-field limit of a particle-based system modeling the behavior of many indistinguishable pedestrians as their number increases. The base model is a modified version of Helbing\\'s social force model. In the mean-field limit, the time-dependent density of two-dimensional pedestrians satisfies a four-dimensional integro-differential Fokker-Planck equation. To approximate the solution of the Fokker-Planck equation we use a time-splitting approach and solve the diffusion part using a Crank-Nicholson method. The advection part is solved using a Lax-Wendroff-Leveque method or an upwind Backward Euler method depending on the advection speed. Moreover, we use multilevel Monte Carlo to estimate observables from the particle-based system. We discuss these numerical methods, and present numerical results showing the convergence of observables that were calculated using the particle-based model as the number of pedestrians increases to those calculated using the probability density function satisfying the Fokker-Planck equation.

  6. Ellipsoid flowed around by a harmonic vector field

    Science.gov (United States)

    Savchenko, A. O.; Savchenko, O. Ya.

    2012-03-01

    We consider the screening of an external magnetic field in which a superconducting ellipsoid is inserted and a change in the velocity distribution in an ideal liquid flowing around an ellipsoid inserted in it. In both cases, the solution is given by a harmonic vector field parallel to the surface near the ellipsoid.

  7. Reducing the Need for Accurate Stream Flow Forecasting for Water Supply Planning by Augmenting Reservoir Operations with Seawater Desalination and Wastewater Recycling

    Science.gov (United States)

    Bhushan, R.; Ng, T. L.

    2014-12-01

    Accurate stream flow forecasts are critical for reservoir operations for water supply planning. As the world urban population increases, the demand for water in cities is also increasing, making accurate forecasts even more important. However, accurate forecasting of stream flows is difficult owing to short- and long-term weather variations. We propose to reduce this need for accurate stream flow forecasts by augmenting reservoir operations with seawater desalination and wastewater recycling. We develop a robust operating policy for the joint operation of the three sources. With the joint model, we tap into the unlimited reserve of seawater through desalination, and make use of local supplies of wastewater through recycling. However, both seawater desalination and recycling are energy intensive and relatively expensive. Reservoir water on the other hand, is generally cheaper but is limited and variable in its availability, increasing the risk of water shortage during extreme climate events. We operate the joint system by optimizing it using a genetic algorithm to maximize water supply reliability and resilience while minimizing vulnerability subject to a budget constraint and for a given stream flow forecast. To compute the total cost of the system, we take into account the pumping cost of transporting reservoir water to its final destination, and the capital and operating costs of desalinating seawater and recycling wastewater. We produce results for different hydro climatic regions based on artificial stream flows we generate using a simple hydrological model and an autoregressive time series model. The artificial flows are generated from precipitation and temperature data from the Canadian Regional Climate model for present and future scenarios. We observe that the joint operation is able to effectively minimize the negative effects of stream flow forecast uncertainty on system performance at an overall cost that is not significantly greater than the cost of a

  8. Numerical analysis of flow fields generated by accelerating flames

    Energy Technology Data Exchange (ETDEWEB)

    Kurylo, J.

    1977-12-01

    Presented here is a numerical technique for the analysis of non-steady flow fields generated by accelerating flames in gaseous media. Of particular interest in the study is the evaluation of the non-steady effects on the flow field and the possible transition of the combustion process to detonation caused by an abrupt change in the burning speed of an initially steady flame propagating in an unconfined combustible gas mixture. Optically recorded observations of accelerating flames established that the flow field can be considered to consist of non-steady flow fields associated with an assembly of interacting shock waves, contact discontinuities, deflagration and detonation fronts. In the analysis, these flow fields are treated as spatially one-dimensional, the influence of transport phenomena is considered to be negligible, and unburned and burned substances are assumed to behave as perfect gases with constant, but different, specific heats. The basis of the numerical technique is an explicit, two step, second order accurate, finite difference scheme employed to integrate the flow field equations expressed in divergence form. The burning speed, governing the motion of the deflagration, is expressed in the form of a power law dependence on pressure and temperature immediately ahead of its front. The steady wave solution is obtained by the vector polar interaction technique, that is, by determining the point of intersection between the loci of end states in the plane of the two interaction invariants, pressure and particle velocity. The technique is illustrated by a numerical example in which a steady flame experiences an abrupt change in its burning speed. Solutions correspond either to the eventual reestablishment of a steady state flow field commensurate with the burning speed or to the transition to detonation. The results are in satisfactory agreement with experimental observations.

  9. Paper-based flow fractionation system for preconcentration and field-flow fractionation.

    Science.gov (United States)

    Hong, Seokbin; Kwak, Rhokyun; Kim, Wonjung

    2015-11-01

    We present a novel paper-based flow fractionation system for preconcentration and field-flow fractionation. The paper fluidic system consisting of a straight channel connected with expansion regions can generate a fluid flow with a constant flow rate for 10 min without any external pumping devices. The flow bifurcates with a fraction ratio of up to 30 depending on the control parameters of the channel geometry. Utilizing this simple paper-based bifurcation system, we developed a continuous-flow preconcentrator and a field-flow fractionator on a paper platform. Our experimental results show that the continuous-flow preconcentrator can produce a 33-fold enrichment of the ion concentration and that the flow fractionation system successfully separates the charged dyes. Our study suggests simple, cheap ways to construct preconcentration and field-flow fractionation systems for paper-based microfluidic diagnostic devices. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP) (NRF-2015R1A2A2A04006181).

  10. Flow Driven by an Archimedean Helical Permanent Magnetic Field. Part I: Flow Patterns and Their Transitions

    Science.gov (United States)

    Wang, Bo; Wang, Xiaodong; Etay, Jacqueline; Na, Xianzhao; Zhang, Xinde; Fautrelle, Yves

    2016-04-01

    In this study, an Archimedean helical permanent magnetic field was constructed and its driving effects on liquid metal were examined. A magnetic stirrer was constructed using a series of arc-like magnets. The helical distribution of its magnetic field, which was confirmed via Gauss probe measurements and numerical simulations, can be considered a combination of rotating and traveling magnetic fields. The characteristics of the flow patterns, particularly the transitions between the meridian secondary flow (two vortices) and the global axial flow (one vortex), driven by this magnetic field were quantitatively measured using ultrasonic Doppler velocimetry. The transient and modulated flow behaviors will be presented in a companion article. The D/ H dimension ratio was used to characterize the transitions of these two flow patterns. The results demonstrated that the flow patterns depend on not only the intrinsic structure of the magnetic field, e.g., the helix lead angle, but also the performance parameters, e.g., the dimensional ratio of the liquid bulk. The notable opposing roles of these two flow patterns in the improvement of macrosegregations when imposing such magnetic fields near the solidifying front were qualitatively addressed.

  11. Prototyping Augmented Reality

    CERN Document Server

    Mullen, Tony

    2011-01-01

    Learn to create augmented reality apps using Processing open-source programming language Augmented reality (AR) is used all over, and you may not even realize it. Smartphones overlay data onto live camera views to show homes for sale, restaurants, or historical sites. American football broadcasts use AR to show the invisible first-down line on the field to TV viewers. Nike and Budweiser, among others, have used AR in ads. Now, you can learn to create AR prototypes using 3D data, Processing open-source programming language, and other languages. This unique book is an easy-to-follow guide on how

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

    Directory of Open Access Journals (Sweden)

    Norimasa Shiomi

    2003-01-01

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

  13. Compressible dynamics of magnetic field lines for incompressible magnetohydrodynamic flows

    International Nuclear Information System (INIS)

    It is demonstrated that the deformation of magnetic field lines in incompressible magnetohydrodynamic flows results from a compressible mapping associated with the transverse motion of fluid particles. Appearance of zeros for the Jacobian of this mapping corresponds to the breaking of magnetic field lines and the local blowup of the magnetic field intensity. The occurrence of such events is found to be unlikely in two dimensions but possible in three dimensions

  14. Flow Field Investigation in a Trapezoidal Duct with Swirl Flow Induced by Impingement Jets

    Institute of Scientific and Technical Information of China (English)

    LIU Haiyong; QIANG Hongfu; LIU Songling; LIU Cunliang

    2011-01-01

    An enlarged model of trapezoidal duct near the leading-edge in the blade is built up. The effects of impingement jets, swirl flow, cross flow and effusion flow are considered. Experiments are performed to measure flow fields in this confined passage and exit holes on one of its side walls. Cross flow and effusion flow are induced in the channel by the outflow of side exit hole (SEH) and film cooling hole (FCH), which are oriented on one end wall and bottom wall of the passage. Detailed flow structures are measured for two impingement angles of 35° and 45° with 6 combinations of outflow ratios. Results show that the small jets impinge the target wall effectively while the large jets contribute to inducing and impelling a strong counter-clockwise vortex in the upper part of the passage. Cross flow plays a dominate role for the flow structures in the passage and exit holes. It deflects jets, enhances swirl and deteriorates side exit conditions. Impingement angle is another significant factor for the flow characteristics. Its effect reveals more evidently with cross flow. Within the present test conditions, the mass flow rates and outflow positions of FCHs have no distinct effect on the main flow structures.

  15. Field observations of a debris flow event in the Dolomites

    Science.gov (United States)

    Berti, Matteo; Genevois, Rinaldo; Simoni, Alessandro; Tecca, Pia Rosella

    1999-09-01

    A debris flow event occurred in June 1997 in the Dolomites (Eastern Alps, Italy). The phenomenon was directly observed in the field and recorded by a video camera near its initiation area. The debris flow originated shortly after an intense rainstorm (25 mm in 30 min) whose runoff mobilised the loose coarse debris that filled the bottom of the channel in its upper part. The analysis of the steep headwater basin indicates a very short concentration time (9-14 min) that fits the quick hydrological response observed in the field. The debris flow mobilisation was not contemporaneous with the arrival of the peak water discharge in the initiation area probably due to the time required for the saturation of the highly conductive channel-bed material. Channel cross-section measurements taken along the flow channel indicate debris flow peak velocity and discharge ranging from 3.1 to 9.0 m/s and from 23 to 71 m 3/s, respectively. Samples collected immediately after deposition were used to determine the water content and bulk density of the material. Channel scouring, fines enrichment and transported volume increase testify erosion and entrainment of material along the flow channel. Field estimates of the rheological properties based on open channel flow of Bingham fluid indicate a yield strength of 5000±400 Pa and relatively low viscosity (60-326 Pa s), probably due to a high percentage of fines (approx. 30%).

  16. Laboratory observation of magnetic field growth driven by shear flow

    International Nuclear Information System (INIS)

    Two magnetic flux ropes that collide and bounce have been characterized in the laboratory. We find screw pinch profiles that include ion flow vi, magnetic field B, current density J, and plasma pressure. The electron flow ve can be inferred, allowing the evaluation of the Hall J×B term in a two fluid magnetohydrodynamic Ohm's Law. Flux ropes that are initially cylindrical are mutually attracted and compress each other, which distorts the cylindrical symmetry. Magnetic field is created via the ∇×ve×B induction term in Ohm's Law where in-plane (perpendicular) shear of parallel flow (along the flux rope) is the dominant feature, along with some dissipation and magnetic reconnection. We predict and measure the growth of a quadrupole out-of-plane magnetic field δBz. This is a simple and coherent example of a shear flow driven dynamo. There is some similarity with two dimensional reconnection scenarios, which induce a current sheet and thus out-of-plane flow in the third dimension, despite the customary picture that considers flows only in the reconnection plane. These data illustrate a general and deterministic mechanism for large scale sheared flows to acquire smaller scale magnetic features, disordered structure, and possibly turbulence

  17. Rapid protein separation and diffusion coefficient measurement by frit inlet flow field-flow fractionation.

    OpenAIRE

    Liu, M. K.; Li, P.; Giddings, J. C.

    1993-01-01

    In this study three flow field-flow fractionation (flow FFF) channels are utilized for the separation of proteins and for the simultaneous measurement of their translational diffusion coefficients, D. One channel has a traditional sample inlet, whereas the other two incorporate a frit inlet design that permits more convenient and rapid sample introduction. The dependence of retention time on D, which leads to differential elution and the opportunity to measure D for protein peaks purified by ...

  18. Characterization of enzymatically synthesized amylopectin analogs via asymmetrical flow field flow fractionation

    NARCIS (Netherlands)

    Ciric, Jelena; Rolland-Sabate, Agnes; Guilois, Sophie; Loos, Katja

    2014-01-01

    Asymmetrical flow field flow fractionation (AF4), when coupled with multi-angle laser light scattering (MALLS), is a very powerful technique for determination of the macromolecular structure of high molar mass (branched) polysaccharides. AF4 is a size fractionation technique just as size exclusion c

  19. Simulations of Viscous Flow Fields of ASTM Assembly and the Effective Average Velocities of Flow Tubes

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; ZHANG Wei-min; CHEN Nai-lu; WANG Ming-hua; LI Lin-lin; Yuan Jian

    2004-01-01

    With the finite element analysis of viscous quenchant flow fields of the ASTM assembly, the effective average velocities of flow tubes are introduced in this paper. And through the results of experiments, the influences of quenchant velocities upon the whole cooling processes are discussed.

  20. Different elution modes and field programming in gravitational field-flow fractionation. III. Field programming by flow-rate gradient generated by a programmable pump

    Czech Academy of Sciences Publication Activity Database

    Plocková, Jana; Chmelík, Josef

    2001-01-01

    Roč. 918, č. 2 (2001), s. 361-370. ISSN 0021-9673 R&D Projects: GA AV ČR IAA4031805 Institutional research plan: CEZ:AV0Z4031919 Keywords : field-flow fractionation * field programming * flow-rate gradients Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.793, year: 2001

  1. Acoustic tomographic imaging of temperature and flow fields in air

    International Nuclear Information System (INIS)

    Acoustic travel-time tomography is a remote sensing technique that uses the dependence of sound speed in air on temperature and wind speed along the sound propagation path. Travel-time measurements of acoustic signals between several sound sources and receivers travelling along different paths through a measuring area give information on the spatial distribution of temperature and flow fields within the area. After a separation of the two influences, distributions of temperature and flow can be reconstructed using inverse algorithms. As a remote sensing method, one advantage of acoustic travel-time tomography is its ability to measure temperature and flow field quantities without disturbing the area under investigation due to insertion of sensors. Furthermore, the two quantities—temperature and flow velocity—can be recorded simultaneously with this measurement method. In this paper, an acoustic tomographic measurement system is introduced which is capable of resolving three-dimensional distributions of temperature and flow fields in air within a certain volume (1.3 m × 1.0 m × 1.2 m) using 16 acoustic transmitter–receiver pairs. First, algorithms for the 3D reconstruction of distributions from line-integrated measurements are presented. Moreover, a measuring apparatus is introduced which is suited for educational purposes, for demonstration of the method as well as for indoor investigations. Example measurements within a low-speed wind tunnel with different incident flow situations (e.g. behind bluff bodies) using this system are shown. Visualizations of the flow illustrate the plausibility of the tomographically reconstructed flow structures. Furthermore, alternative individual measurement methods for temperature and flow speed provide comparable results

  2. Flow field measurements in the cell culture unit

    Science.gov (United States)

    Walker, Stephen; Wilder, Mike; Dimanlig, Arsenio; Jagger, Justin; Searby, Nancy

    2002-01-01

    The cell culture unit (CCU) is being designed to support cell growth for long-duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity ( micro g), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground-based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the

  3. Ulysses magnetic field observations of fluctuations within polar coronal flows

    Science.gov (United States)

    Horbury, T.; Balogh, A.; Forsyth, R. J.; Smith, E. J.

    1995-01-01

    The Ulysses spacecraft has gathered data from within flows from the Sun's southern polar coronal hole, the first in situ measurement of this region. We present a brief analysis of the heliospheric magnetic field data from this region, using a fractal method. As is the case near the ecliptic, estimated spectral exponents are near 5/3 on spacecraft scales of seconds to minutes. On longer time scales, however, there appears to be a significantly different population in polar flows, which is similar to that found by the Helios spacecraft in fast solar wind flows at 0.3 AU.

  4. Determination of the functioning parameters in asymmetrical flow field-flow fractionation with an exponential channel.

    Science.gov (United States)

    Déjardin, P

    2013-08-30

    The flow conditions in normal mode asymmetric flow field-flow fractionation are determined to approach the high retention limit with the requirement d≪l≪w, where d is the particle diameter, l the characteristic length of the sample exponential distribution and w the channel height. The optimal entrance velocity is determined from the solute characteristics, the channel geometry (exponential to rectangular) and the membrane properties, according to a model providing the velocity fields all over the cell length. In addition, a method is proposed for in situ determination of the channel height. PMID:23885667

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

    Science.gov (United States)

    Finlay, Christopher C.; Amit, Hagay

    2011-05-01

    We present a method to estimate the typical magnitude of flow close to Earth's core surface based on observational knowledge of the geomagnetic main field (MF) and its secular variation (SV), together with prior information concerning field-flow alignment gleaned from numerical dynamo models. An expression linking the core surface flow magnitude to spherical harmonic spectra of the MF and SV is derived from the magnetic induction equation. This involves the angle γ between the flow and the horizontal gradient of the radial field. We study γ in a suite of numerical dynamo models and discuss the physical mechanisms that control it. Horizontal flow is observed to approximately follow contours of the radial field close to high-latitude flux bundles, while more efficient induction occurs at lower latitudes where predominantly zonal flows are often perpendicular to contours of the radial field. We show that the amount of field-flow alignment depends primarily on a magnetic modified Rayleigh number Raη=αg0ΔTD/ηΩ, which measures the vigour of convective driving relative to the strength of magnetic dissipation. Synthetic tests of the flow magnitude estimation scheme are encouraging, with results differing from true values by less than 8 per cent. Application to a high-quality geomagnetic field model based on satellite observations (the xCHAOS model in epoch 2004.0) leads to a flow magnitude estimate of 11-14 km yr-1, in accordance with previous estimates. When applied to the historical geomagnetic field model gufm1 for the interval 1840.0-1990.0, the method predicts temporal variations in flow magnitude similar to those found in earlier studies. The calculations rely primarily on knowledge of the MF and SV spectra; by extrapolating these beyond observed scales the influence of small scales on flow magnitude estimates is assessed. Exploring three possible spectral extrapolations we find that the magnitude of the core surface flow, including small scales, is likely

  6. The Flow Field Analysis and Flow Calculation of Ultrasonic Flowmeter Based on the Fluent Software

    OpenAIRE

    Ling Guo; Yue Sun; Ling Liu; Zhixi Shen; Ruizhen Gao; Kai (Jackie) Zhao

    2014-01-01

    We can build the three-dimensional structure model based on the Gambit software and achieve the distribution of flow field in the pipe and reflux flow condition at the position of transducer in regard to the real position of transducer according to the Fluent software. Under the framework, define the reflux length based on the distance of reflux along the channel and evaluate the effect of reflux on flow field. Then we can correct the power factor with the transmission speed difference method...

  7. Experimental study on visualization of the flow field in microtube

    Institute of Scientific and Technical Information of China (English)

    LIU Zhigang; ZHAO Yaohua

    2005-01-01

    An experimental study was conducted to visualize the flow field and confirm the transitional Reynolds number from laminar to turbulent flow, as distilled water flows through quartz glass microtubes with inner diameter 315 and 520 μm. With gentian violet as colorant, the flow field pictures in the microtube, and therefore, is shot by a CCD camera with a microscope at different Reynolds numbers. Pressure drop data were also used to characterize the friction factor for those microtubes in the Reynolds number range of 200―2300. The experimental results clearly showed that the flow in the microtube was the laminar state and the friction factors agreed well with the Poiseuille equations when the Reynolds number was low. As the Reynolds number was larger than 1200 and 1500 for the microtube with inner diameter 315 and 520 μm, respectively, the friction factor departed from the classical laminar solution due to the earlier transition from laminar to turbulent flow. The flow turned into full turbulent when the Reynolds number reached 1500―1800.

  8. Complex analysis with applications to flows and fields

    CERN Document Server

    Braga da Costa Campos, Luis Manuel

    2012-01-01

    Complex Analysis with Applications to Flows and Fields presents the theory of functions of a complex variable, from the complex plane to the calculus of residues to power series to conformal mapping. The book explores numerous physical and engineering applications concerning potential flows, the gravity field, electro- and magnetostatics, steady heat conduction, and other problems. It provides the mathematical results to sufficiently justify the solution of these problems, eliminating the need to consult external references.The book is conveniently divided into four parts. In each part, the ma

  9. Augmentation mammoplasty

    International Nuclear Information System (INIS)

    Seventy-five cases of breast implants have been reviewed. Two categories of abnormalities were identified: those involving the implant itself and those within the breast parenchyma. Complications of the implant itself include leakage, fibrous capsular contraction, traumatic rupture, displacement, and collapse. Concomitant breast parenchymal abnormalities include breast carcinoma, cysts, solid masses, and clusters of microcalcifications. Mammographic technique is critical and often involves manual settings and special views. Mammography and US in conjunction with physical examination play an important role in detecting breast pathology in the augmented breast

  10. Continuous flow augments reactivity of rabbit carotid artery by reducing bioavailability of NO despite an increase in release of EDHF

    DEFF Research Database (Denmark)

    Rasmussen, Lasse Enkebølle; Vanhoutte, Paul M. G.; Jensen, Boye L.; Skøtt, Ole

    2006-01-01

    endothelial small- and intermediate-conductance calcium-activated potassium channels by apamin plus 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34). These experiments demonstrate that continuous flow increases the constriction evoked by alpha(1)-adrenergic activation in the rabbit carotid artery...

  11. A study on rotational augmentation using CFD analysis of flow in the inboard region of the MEXICO rotor blades

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Sørensen, Niels N.

    2015-01-01

    This work presents an analysis of data from existing as well as new full-rotor computational fluid dynamics computations on the MEXICO rotor, with focus on the flow around the inboard parts of the blades. The boundary layer separation characteristics on the airfoil sections in the inboard parts...

  12. Mean-field effects on matter and antimatter elliptic flow

    International Nuclear Information System (INIS)

    We report our recent work on mean-field potential effects on the elliptic flows of matters and antimatters in heavy ion collisions leading to the production of a baryon-rich matter. Within the framework of a multiphase transport (AMPT) model that includes both initial partonic and final hadronic interactions, we have found that including mean-field potentials in the hadronic phase leads to a splitting of the elliptic flows of particles and their antiparticles, providing thus a plausible explanation of the different elliptic flows between p and anti-p, K+ and K-, and π+ and π- observed by the STAR Collaboration in the Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider (RHIC). Using a partonic transport model based on the Nambu-Jona-Lasinio (NJL) model, we have also studied the effect of scalar and vector mean fields on the elliptic flows of quarks and antiquarks in these collisions. Converting quarks and antiquarks at hadronization to hadrons via the quark coalescence model, we have found that the elliptic flow differences between particles and antiparticles also depend on the strength of the quark vector coupling in baryon-rich quark-gluon plasma, providing thus the possibility of extracting information on the latter's properties from the BES program at RHIC. (authors)

  13. Numerical Simulation of Laminar Flow Field in a Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    范茏; 王卫京; 杨超; 毛在砂

    2004-01-01

    Stirred tanks are used extensively in process industry and one of the most commonly used impellers in stirred tanks is the R.ushton disk turbine. Surprisingly few data are available regarding flow and mixing in stirred-tank reactors with Rushton turbine in the laminar regime, in particular the laminar flow in baffled tanks.In this paper, the laminar flow field in a baffled tank stirred by a standard R.ushton turbine is simulated with the improved inner-outer iterative method. The non-inertial coordinate system is used for the impeller region, which is in turn used as the boundary conditions for iteration. It is found that the simulation results are in good agreement with previous experiments. In addition, the flow number and impeller power number calculated from the simulated flow field are in satisfactory agreement with experimental data. This numerical method allows prediction of flow structure requiring no experimental data as the boundary conditions and has the potential of being used to scale-up and design of related process equipment.

  14. Solar-Cycle Evolution of Subsurface Flows and Magnetic Field

    Science.gov (United States)

    Kosovichev, Alexander G.; Zhao, Junwei

    2016-05-01

    Local helioseismology and magnetic field measurements from the HMI instrument on SDO provide unique high-resolution data that allow us to investigate detailed dynamics of the upper convection zone and its relation to the magnetic field evolution during the first five years of the current solar cycle. This study is focused on the understanding the role of the near-surface shear layer (NSSL) in the dynamo process, generation, emergence and transport of the solar magnetic flux. The helioseismology data represent 3D flow maps in the depth range of 0-20 Mm, obtained uninterruptedly every 8 hours for almost the whole solar disk with the spatial sampling of two arcsec. We calculate the flow characteristics (such as divergence, vorticity and kinetic helicity) on different spatio-temporal scales from supergranulation to global-scale zonal and meridional flows. We investigate the multi-scale organization of the subsurface flows, including the inflows into active regions, the hemispheric `flip-flop’ asymmetry of variations of the meridional flows, the structure and dynamics of torsional oscillations, and compare the flow behavior with the evolution of the observed magnetic activity of the current cycle.

  15. FLOW FIELD IN SCOURED ZONE OF CHANNEL CONTRACTIONS

    Institute of Scientific and Technical Information of China (English)

    Rajkumar V. RAIKAR; Subhasish DEY

    2004-01-01

    Experiments were conducted in a laboratory flume to measure the two-dimensional turbulent flow field in the scoured zone of channel contractions under a clear-water scour condition. The Acoustic Doppler Velocimeter (ADV) was used to detect the flow field at different vertical lines along the centerline of uncontracted (main channel) and contracted zones of the channel. The distributions of time-averaged velocity components, turbulent intensity, turbulent kinetic energy, and Reynolds stresses are presented in nondimensional graphical form. The bed shear stresses are computed from the measured Reynolds stresses being in threshold condition within the zone of contraction where bed was scoured. The data presented in this paper would be useful to the investigators for the development of kinematic flow model and morphological model of scour at a channel or river contraction.

  16. Design of vortex fluid amplifiers with asymmetrical flow fields.

    Science.gov (United States)

    Lawley, T. J.; Price, D. C.

    1972-01-01

    Variation of geometric parameters, including supply area, control area, chamber length, and outlet diameter, of a large scale, modular design vortex fluid amplifier with single supply and control jets, has confirmed and extended a previously published design method, developed for vortex amplifiers with symmetric flow fields. This allows application of the method to devices which are more representative of practical, production type components.

  17. Estimation of Centers and Stagnation points in optical flow fields

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1997-01-01

    allows us to give a qualitative local description of the flow field and to estimate the position of stagnation points (e.g. nodes, saddles, and centers). We will apply the algorithm to two data sets. The first sequence consists of infrared images from the meteorological satellite Meteosat. Here the...

  18. Interdependence of centrifugal compressor blade geometry and relative flow field

    Science.gov (United States)

    Krain, H.

    1985-03-01

    The influence of the impeller blade geometry on the calculated relative flow field has been studied by means of an impeller design program available at DFVLR (Krain, 1984). Several geometrical parameters were varied, however, the meridional channel geometry was always kept constant. By this approach the blade wrap angle has been found to react significantly on the relative flow which is illustrated by comparing two designs with different wrap angles. Primarily in the hub/leading edge area a better boundary layer flow connected with a reduction of blade loading was obtained by increasing the wrap angle. But also in the shroud/pressure side area the increased blade looping attributed to an additional flow stabilization.

  19. Numerical simulation of electromagnetic and flow fields of TiAI melt under electric field

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong; Ding Hongsheng; Jiang Sanyong; Chen Ruirun; Guo Jingjie

    2010-01-01

    This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAI melt under two electric fields. FEM (Finite Element Method) and APDL (ANSYS Parametric Design Language) were employed to perform the simulation, model setup, loading and problem solving. The melt in molds of same cross section area with different flakiness ratio (i.e. width/depth) under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field. The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1. The melt is driven bipolarly from the center in each electric field. It is also found that the pulse electric field actuates the TiAI melt to flow stronger than what the sinusoidal electric field does.

  20. Flow of a conducting fluid in a rotating magnetic field

    International Nuclear Information System (INIS)

    The motion of a conducting fluid in a rotating magnetic field has been investigated in many studies. These studies had one substantial drawback: the magnetic field induction was taken to be uniform along the radius, and the velocity profile uvar-phi was linear. In real devices, however, the magnetic field is nonuniform, affecting the profile u substantially. In the present study the authors investigate experimentally the motion of a conducting fluid in a cylindrical container with the ratio H/R ≅ 1 in a nonuniform rotating field. Also considered is an approximate analytic flow model of a rotating fluid. The proposed analytical model makes it possible to determine the var-phi-component of the velocity fluid flow in a rotating field with H ≅ R. The deviation of the model from the experimental results is related to the fact that the solution for the boundary layer at the bottom was selected from the equation for an Eckmann layer of an infinite disk. Therefore, the flow of the r-component is somewhat enhanced in this boundary layer. 10 refs., 6 figs

  1. Nanoparticle separation with a miniaturized asymmetrical flow field-flow fractionation cartridge

    OpenAIRE

    David eMüller; Stefano eCattaneo; Florian eMeier; Roland eWelz; deMello, Andrew J.

    2015-01-01

    Asymmetrical Flow Field-Flow Fractionation (AF4) is a separation technique applicable to particles over a wide size range. Despite the many advantages of AF4, its adoption in routine particle analysis is somewhat limited by the large footprint of currently available separation cartridges, extended analysis times and significant solvent consumption. To address these issues, we describe the fabrication and characterization of miniaturized AF4 cartridges. Key features of the scale-down platform ...

  2. Nanoparticle separation with a miniaturized asymmetrical flow field-flow fractionation cartridge

    OpenAIRE

    Müller, David; Cattaneo, Stefano; Meier, Florian; Welz, Roland; de Mello, Andrew J.

    2015-01-01

    Asymmetrical Flow Field-Flow Fractionation (AF4) is a separation technique applicable to particles over a wide size range. Despite the many advantages of AF4, its adoption in routine particle analysis is somewhat limited by the large footprint of currently available separation cartridges, extended analysis times and significant solvent consumption. To address these issues, we describe the fabrication and characterization of miniaturized AF4 cartridges. Key features of the down-scaled platform...

  3. Laboratory and field trials of Coriolis mass flow metering for three-phase flow measurement

    Science.gov (United States)

    Zhou, Feibiao; Henry, Manus; Tombs, Michael

    2014-04-01

    A new three-phase flow metering technology is discussed in this paper, which combines Coriolis mass flow and water cut readings and without applying any phase separation [1]. The system has undergone formal laboratory trials at TUV NEL (National Engineering Laboratory), UK and at VNIIR (National Flow Laboratory), Kazan, Russia; a number of field trials have taken place in Russia. Laboratory trial results from the TUV NEL will be described in detail. For the 50mm (2") metering system, the total liquid flow rate ranged from 2.4 kg/s up to 11 kg/s, the water cut ranged from 0% to 100%, and the gas volume fraction (GVF) from 0 to 50%. In a formally observed trial, 75 test points were taken at a temperature of approximately 40 °C and with a skid inlet pressure of approximately 350 kPa. Over 95% of the test results fell within the desired specification, defined as follows: the total (oil + water) liquid mass flow error should fall within ± 2.5%, and the gas mass flow error within ± 5.0%. The oil mass flow error limit is ± 6.0% for water cuts less than 70%, while for water cuts between 70% and 95% the oil mass flow error limit is ± 15.0%. These results demonstrate the potential for using Coriolis mass flow metering combined with water cut metering for three-phase (oil/water/gas) measurement.

  4. Visualization of exchange flow and simulation of flow rate in unstably stratified field

    International Nuclear Information System (INIS)

    The exchange flow under unstably stratified field may occur following Rayleigh-Taylor instability, the example is pipe ruptures in a high temperature gas-cooled nuclear reactor, i.e., HTGR. The exchange flows in density different gases were investigated through a vertical narrow tube. The experiments were carried out in a test chamber filled with helium and the flow behavior was visualized using the smoke methods and recorded by the high-speed camera. The image of the flow was transferred to digital data, and then the slow flow velocity was measured by PIV software. Numerical analysis was carried out by the 3D code of moving particle with Lagrange method. As the result, it was clarified that the flume and 3D vortex mechanism. (author)

  5. Navier-Stokes flow field analysis of compressible flow in a pressure relief valve

    Science.gov (United States)

    Vu, Bruce T.; Wang, Ten-See; Shih, Ming-Hsin; Soni, Bharat K.

    1993-07-01

    The present study was motivated to analyze the complex flow field involving gaseous oxygen (GOX) flow in a relief valve (RV). The 9391 RV, pictured in Figure 1, was combined with the pilot valve to regulate the actuation pressure of the main valve system. During a high-pressure flow test at Marshall Space Flight Center (MSFC) the valve system developed a resonance chatter, which destroyed most of the valve body. Figures 2-4 show the valve body before and after accident. It was understood that the subject RV has never been operated at 5500 psia. In order to fully understand the flow behavior in the RV, a computational fluid dynamics (CFD) analysis is carried out to investigate the side load across the piston sleeve and the erosion patterns resulting from flow distribution around piston/nozzle interface.

  6. Magnetic Fields in Cooling Flow Clusters: A Critical View

    CERN Document Server

    Soker, Noam

    2010-01-01

    Shortly after the first results of Chandra and XMM-Newton appeared, many researchers in the field abandoned the term "cooling flow clusters" in favor of the name "cool core clusters". This change, I argue, has been causing damage by promoting the view that there is no substantial cooling in these clusters. In this contribution I discuss the following points, with emphasize on the last one that deals with magnetic fields in cooling flow clusters. (1) Both AGN-feedback and hot-gas cooling to form stars occur during galaxy formation as well as in cooling flow clusters. Ignoring cooling of the intra-cluster medium, as implied by the term "cool core", does not encourage comparative study of AGN feedback in cooling flow clusters with that of galaxy formation. (2) The line of thought that there is no cooling might lead to wrong questions and research directions. (3) A key question in both cooling flow clusters and during galaxy formation is the mode of accretion by the super massive black hole (SMBH). When cooling i...

  7. Subsurface magnetic field and flow structure of simulated sunspots

    CERN Document Server

    Rempel, Matthias

    2011-01-01

    We present a series of numerical sunspot models addressing the subsurface field and flow structure in up to 16 Mm deep domains covering up to 2 days of temporal evolution. Changes in the photospheric appearance of the sunspots are driven by subsurface flows in several Mm depth. Most of magnetic field is pushed into a downflow vertex of the subsurface convection pattern, while some fraction of the flux separates from the main trunk of the spot. Flux separation in deeper layers is accompanied in the photosphere with light bridge formation in the early stages and formation of pores separating from the spot at later stages. Over a time scale of less than a day we see the development of a large scale flow pattern surrounding the sunspots, which is dominated by a radial outflow reaching about 50% of the convective rms velocity in amplitude. Several components of the large scale flow are found to be independent from the presence of a penumbra and the associated Evershed flow. While the simulated sunspots lead to blo...

  8. Time-Dependent of Accretion Flow with Toroidal Magnetic Field

    CERN Document Server

    Khesali, Alireza

    2008-01-01

    In the present study time evolution of quasi-spherical polytropic accretion flow with toroidal magnetic field was investigated. The study especially focused the astrophysically important case in which the adiabatic exponent $\\gamma=5/3$. In this scenario, it was assumed that the angular momentum transport is due to viscous turbulence and used $\\alpha$-prescription for kinematic coefficient of viscosity. The equations of accretion flow are solved in a simplified one-dimensional model that neglects the latitudinal dependence of the flow. In order to solve the integrated equations which govern the dynamical behavior of the accretion flow, self-similar solution was used. The solution provides some insight into the dynamics of quasi-spherical accretion flow and avoids many of the strictures of the steady self-similar solution. The effect of the toroidal magnetic field is considered with additional variable $\\beta[=p_{mag}/p_{gas}]$, where $p_{mag}$ and $p_{gas}$ are the magnetic and gas pressure, respectively. The...

  9. Transient simulation in interior flow field of lobe pump

    International Nuclear Information System (INIS)

    The subject of this paper is mainly focused on the development and control of the double folium and trifolium lobe pump profiles by using the principle of involute engagement and use CAD to get an accurate involute profile. We use the standard k-ε turbulence model and PISO algorithm based on CFD software FLUENT. The dynamic mesh and UDF technology is introduced to simulate the interior flow field inside a lobe pump, and the variation of interior flow field under the condition of the lobe rotating is analyzed. We also analyse the influence produced by the difference in lobes, and then reveal which lobe is best. The results show that dynamic variation of the interior flow field is easily obtained by dynamic mesh technology and the distribution of its pressure and velocity. Because of the small gaps existing between the rotors and pump case, the higher pressure area will flow into the lower area though the small gaps which cause the working area keep with higher pressure all the time. Both of the double folium and trifolium are existing the vortex during the rotting time and its position, size and shape changes all the time. The vortexes even disappear in a circle period and there are more vortexes in double folium lobe pump. The velocity and pressure pulsation of trifolium pump are lower than that of the double folium

  10. Performance enhancement of iron-chromium redox flow batteries by employing interdigitated flow fields

    Science.gov (United States)

    Zeng, Y. K.; Zhou, X. L.; Zeng, L.; Yan, X. H.; Zhao, T. S.

    2016-09-01

    The catalyst for the negative electrode of iron-chromium redox flow batteries (ICRFBs) is commonly prepared by adding a small amount of Bi3+ ions in the electrolyte and synchronously electrodepositing metallic particles onto the electrode surface at the beginning of charge process. Achieving a uniform catalyst distribution in the porous electrode, which is closely related to the flow field design, is critically important to improve the ICRFB performance. In this work, the effects of flow field designs on catalyst electrodeposition and battery performance are investigated. It is found that compared to the serpentine flow field (SFF) design, the interdigitated flow field (IFF) forces the electrolyte through the porous electrode between the neighboring channels and enhances species transport during the processes of both the catalyst electrodeposition and iron/chromium redox reactions, thus enabling a more uniform catalyst distribution and higher mass transport limitation. It is further demonstrated that the energy efficiency of the ICRFB with the IFF reaches 80.7% at a high current density (320 mA cm-2), which is 8.2% higher than that of the ICRFB with the SFF. With such a high performance and intrinsically low-cost active materials, the ICRFB with the IFF offers a great promise for large-scale energy storage.

  11. Numerical simulation of three-dimensional boattail afterbody flow fields

    Science.gov (United States)

    Deiwert, G. S.

    1980-01-01

    The thin shear layer approximations of the three-dimensional, compressible Navier-Stokes equations are solved for subsonic, transonic, and supersonic flow over axisymmetric boattail bodies at moderate angles of attack. The plume is modeled by a solid body configuration identical to those used in experimental tests. An implicit algorithm of second-order accuracy is used to solve the equations on the ILLIAC IV computer. The turbulence is expressed by an algebraic model applicable to three-dimensional flow fields with moderate separation. The computed results compare favorably with three different sets of experimental data reported by Reubush, Shrewsbury, and Benek, respectively

  12. Numerical simulation of the flow field around a complete aircraft

    Science.gov (United States)

    Shang, J. S.; Scherr, S. J.

    1986-01-01

    The present effort represents a first attempt of numerical simulation of the flow field around a complete aircraft-like, lifting configuration utilizing the Reynolds averaged Navier-Stokes equations. The numerical solution generated for the experimental aircraft concept X24C-10D at a Mach number of 5.95 not only exhibited accurate prediction of detailed flow properties but also of the integrated aerodynamic coefficients. In addition, the present analysis demonstrated that a page structure of data collected into cyclic blocks is an efficient and viable means for processing the Navier-Stokes equations on the CRAY XMP-22 computer with external memory device.

  13. Local Flow Field and Slip Length of Superhydrophobic Surfaces

    Science.gov (United States)

    Schäffel, David; Koynov, Kaloian; Vollmer, Doris; Butt, Hans-Jürgen; Schönecker, Clarissa

    2016-04-01

    While the global slippage of water past superhydrophobic surfaces has attracted wide interest, the local distribution of slip still remains unclear. Using fluorescence correlation spectroscopy, we performed detailed measurements of the local flow field and slip length for water in the Cassie state on a microstructured superhydrophobic surface. We revealed that the local slip length is finite, nonconstant, anisotropic, and sensitive to the presence of surfactants. In combination with numerical calculations of the flow, we can explain all these properties by the local hydrodynamics.

  14. Flow field interference characteristic of axial ring wing configuration

    OpenAIRE

    Qi, Duo; Jinfu, Feng; Jiaqiang, Zhang; Yongli, Li

    2016-01-01

    To analyze the air flow interference between upper and lower wings in axial ring wing configuration, NASA SC(2)-1006 supercritical airfoil is chosen as the basic airfoil. Flow field around the double-wing structure with different relative distances between upper and lower wings is numerically simulated, using SST  turbulence model, and the numerical conclusion about the influence of relative distance D/L on the aerodynamic performance is drawn. It is shown that, at the speed Ma = 0.8, reflect...

  15. The 3D Flow Field Around an Embedded Planet

    CERN Document Server

    Fung, Jeffrey; Wu, Yanqin

    2015-01-01

    Understanding the 3D flow topology around a planet embedded in its natal disk is crucial to the study of planet formation. 3D modifications to the well-studied 2D flow topology have the potential to resolve longstanding problems in both planet migration and accretion. We present a detailed analysis of the 3D isothermal flow field around a 5 Earth-mass planet on a fixed circular orbit, simulated using our high-resolution multi-GPU hydrodynamics code PEnGUIn. We show that, overall, the horseshoe region has a columnar structure extending vertically much beyond the Hill sphere of the planet. This columnar structure is only broken for some of the widest horseshoe streamlines, along which high altitude fluid descends and converges rapidly toward the planet, enters its Bondi sphere, performs one horseshoe turn, and exits radially in the midplane. A portion of this flow gathers enough speed to exit the horseshoe region altogether. We call this newly identified feature the "transient" horseshoe flow. As the flow conti...

  16. Post-processing methods of PIV instantaneous flow fields for unsteady flows in turbomachines

    OpenAIRE

    Cavazzini, G; A. Dazin; Pavesi, G; Dupont, P.; Bois, G.

    2012-01-01

    The Particle Image Velocimetry is undoubtedly one of the most important technique in Fluid-dynamics since it allows to obtain a direct and instantaneous visualization of the flow field in a non-intrusive way. This innovative technique spreads in a wide number of research fields, from aerodynamics to medicine, from biology to turbulence researches, from aerodynamics to combustion processes. The book is aimed at presenting the PIV technique and its wide range of possible applications so as to p...

  17. Elevator mode convection in flows with strong magnetic fields

    Science.gov (United States)

    Liu, Li; Zikanov, Oleg

    2015-04-01

    Instability modes in the form of axially uniform vertical jets, also called "elevator modes," are known to be the solutions of thermal convection problems for vertically unbounded systems. Typically, their relevance to the actual flow state is limited by three-dimensional breakdown caused by rapid growth of secondary instabilities. We consider a flow of a liquid metal in a vertical duct with a heated wall and strong transverse magnetic field and find elevator modes that are stable and, thus, not just relevant, but a dominant feature of the flow. We then explore the hypothesis suggested by recent experimental data that an analogous instability to modes of slow axial variation develops in finite-length ducts, where it causes large-amplitude fluctuations of temperature. The implications for liquid metal blankets for tokamak fusion reactors that potentially invalidate some of the currently pursued design concepts are discussed.

  18. Elevator mode convection in flows with strong magnetic fields

    International Nuclear Information System (INIS)

    Instability modes in the form of axially uniform vertical jets, also called “elevator modes,” are known to be the solutions of thermal convection problems for vertically unbounded systems. Typically, their relevance to the actual flow state is limited by three-dimensional breakdown caused by rapid growth of secondary instabilities. We consider a flow of a liquid metal in a vertical duct with a heated wall and strong transverse magnetic field and find elevator modes that are stable and, thus, not just relevant, but a dominant feature of the flow. We then explore the hypothesis suggested by recent experimental data that an analogous instability to modes of slow axial variation develops in finite-length ducts, where it causes large-amplitude fluctuations of temperature. The implications for liquid metal blankets for tokamak fusion reactors that potentially invalidate some of the currently pursued design concepts are discussed

  19. Elevator mode convection in flows with strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Li; Zikanov, Oleg, E-mail: zikanov@umich.edu [Department of Mechanical Engineering, University of Michigan-Dearborn, 48128-1491 Michigan (United States)

    2015-04-15

    Instability modes in the form of axially uniform vertical jets, also called “elevator modes,” are known to be the solutions of thermal convection problems for vertically unbounded systems. Typically, their relevance to the actual flow state is limited by three-dimensional breakdown caused by rapid growth of secondary instabilities. We consider a flow of a liquid metal in a vertical duct with a heated wall and strong transverse magnetic field and find elevator modes that are stable and, thus, not just relevant, but a dominant feature of the flow. We then explore the hypothesis suggested by recent experimental data that an analogous instability to modes of slow axial variation develops in finite-length ducts, where it causes large-amplitude fluctuations of temperature. The implications for liquid metal blankets for tokamak fusion reactors that potentially invalidate some of the currently pursued design concepts are discussed.

  20. Longitudinal Dispersivity in a Radial Diverging Flow Field

    Science.gov (United States)

    Seaman, J. C.; Wilson, M.; Bertsch, P. M.; Aburime, S. A.

    2005-12-01

    Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore, a series of field experiments using tritiated water and several other commonly used hydrologic tracers (Br, Cl, FBAs) were conducted in the water-table aquifer on the U.S. Department of Energy's Savannah River Site (Aiken, SC) to evaluate solute transport processes in a diverging radial flow field. For each experiment, tracer-free groundwater was injected for approximately 24 hours at a fixed rate of 56.7 L/min (15 gpm) to establish a forced radial gradient prior to the introduction of a tracer pulse. After the tracer pulse, the forced gradient was maintained throughout the experiment using non-labeled groundwater. Tracer migration was monitored using a set of six sampling wells radially spaced at approximate distances of 1.5, 3, and 4.5 meters from a central injection well. Each sampling well was further divided into three discrete sampling depths that were monitored continuously throughout the course of the tracer experiment. At various time intervals, discrete groundwater samples were collected from all 18 sampling ports for tritium analysis. Longitudinal dispersivity for tritium breakthrough at each sampling location was estimated using analytical approximations of the convection dispersion equation (CDE) for radial flow assuming an instantaneous Dirac pulse and a pulse of known duration. The results were also compared to dispersivity values derived from fitting the tracer data to analytical solutions derived from assuming uniform flow conditions. Tremendous variation in dispersivity values and tracer arrival

  1. A high-performance flow-field structured iron-chromium redox flow battery

    Science.gov (United States)

    Zeng, Y. K.; Zhou, X. L.; An, L.; Wei, L.; Zhao, T. S.

    2016-08-01

    Unlike conventional iron-chromium redox flow batteries (ICRFBs) with a flow-through cell structure, in this work a high-performance ICRFB featuring a flow-field cell structure is developed. It is found that the present flow-field structured ICRFB reaches an energy efficiency of 76.3% with a current density of 120 mA cm-2 at 25 °C. The energy efficiency can be as high as 79.6% with an elevated current density of 200 mA cm-2 at 65 °C, a record performance of the ICRFB in the existing literature. In addition, it is demonstrated that the energy efficiency of the battery is stable during the cycle test, and that the capacity decay rate of the battery is 0.6% per cycle. More excitingly, the high performance of the flow-field structured battery significantly lowers the capital cost at 137.6 kWh-1, which is 28.2% lower than that of the conventional ICRFB for 8-h energy storage.

  2. Inverse Simulation of Field Infiltration Experiment Counting Preferential Flow

    Science.gov (United States)

    Zumr, David; Snehota, Michal; Nemcova, Renata; Dohnal, Michal; Cislerova, Milena

    2010-05-01

    The field tension and ponded infiltration experiments were conducted to monitor and describe irregularities of moisture propagation and to estimate the soil hydraulic properties (Distric Cambisol, Korkusova Hut, Sumava). On these soils the preferential pathways have been observed in several scales with the use of dye tracers, MRI and CT imaging. Preferential behavior was detected also during laboratory infiltration experiments. The flow irregularities are credited to variable air entrapment at the beginning of infiltrations. The field infiltration experiment was carried out in a shallow pit for a period of one day. The upper boundary condition was controlled by the tension disk infiltrometer, the propagation of a water front was monitored by two tensiometers installed in two depths below the infiltration disk. The propagation of saline solution front during ponded infiltration was visualized with high resolution electrical resistivity tomography (ERT). Infiltration experiments were monitored with TDR probes, tensiometers and ERT. Zones of preferential flow were determined through analyses of photographs taken during laboratory dye tracer infiltration experiments performed on undisturbed soil samples. Connectivity, volumetric ratio and spatial development of preferential pathways were evaluated as the necessary information for numerical simulations of flow using dual-permeability approach. 2D axisymetric numerical simulations were conducted to evaluate the results of the experiment. The parameter estimator PEST coupled with the simulation code S2D_DUAL (Vogel et al., 2000) were employed. Two different approaches were used: 1. Single-domain approach based on Richards' equation. 2. Dual-permeability approach based on two interacting water flow domains (matrix and preferential domains), each governed by one Richards' equation. Concerning the existence of preferential flow on investigated soil, the dual-permeability model gives a better picture of the flow regime. The

  3. Unsteady Simulation of a Landing-Gear Flow Field

    Science.gov (United States)

    Li, Fei; Khorrami, Mehdi R.; Malik, Mujeeb R.

    2002-01-01

    This paper presents results of an unsteady Reynolds-averaged Navier-Stokes simulation of a landing-gear flow field. The geometry of the four-wheel landing gear assembly consists of several of the fine details including the oleo-strut, two diagonal struts, a door, yokes/pin and a flat-plate simulating the wing surface. The computational results, obtained by using 13.3 million grid points, are presented with an emphasis on the characteristics of the unsteadiness ensuing from different parts of the landing-gear assembly, including vortex shedding patterns and frequencies of dominant oscillations. The results show that the presence of the diagonal struts and the door significantly influence the flow field. Owing to the induced asymmetry, vortices are shed only from one of the rear wheels and not the other. Present computations also capture streamwise vortices originating from the upstream corners of the door.

  4. The Numerical Analysis of Flow Field on Warship Deck

    Directory of Open Access Journals (Sweden)

    Kwan Ouyang

    2015-03-01

    Full Text Available This study aims to simulate the exhaust flow field of ship by the method of computational fluid dynamics (CFD concerning with the interference by exhaust temperature, shape of stack and rolling angles etc.. In this research wind tunnel test for a corvette has been performed to attain associated experimental data, which were used as a reference basis. During simulation process several configurations of stacks have been selected, and combining with various rolling angles, exhaust temperatures and velocities, we have generated numerous cases from which the diffusion paths and temperature distribution of the exhaust flow field can be clearly observed and analyzed. In terms of numerical simulation, the packaged program computational fluid dynamics software has been adopted. The simulation results also possess the same trend as the experimental data, which have initially confirmed the methods developed here can be used for the arrangement of stack and superstructure at the stage of initial and conceptual design of ships.

  5. Flow-induced Crystallization of Long Chain Aliphatic Polyamides under a Complex Flow Field

    Science.gov (United States)

    Dong, Xia; Gao, Yunyun; Wang, Lili; Wang, Dujin

    The present work deals with the flow-induced multiple orientations and crystallization structure of polymer melts under a complex flow field. This complex flow field is characteristic of the consistent coupling of extensional ``pulse'' and closely followed shear flow in a narrow channel. Utilizing an ingenious combination of an advanced micro-injection device and long chain aliphatic polyamides, the flow-induced crystallization morphology was well preserved for ex-situ synchrotron micro-focused wide angle X-ray scattering as well as small angle X-ray scattering. The experimental results clearly indicate that the effect of extensional pulse on the polymer melt is restrained and further diminished due to either the transverse tumble of fountain flow or the rapid retraction of stretched high molecular weight tails. However, the residual shish-kebab structures in the core layer of the far-end of channel suggest that the effect of extensional pulse should be considered in the small-scaled geometries or under the high strain rate condition. The authors thank the financial support from MOST (2013BAE02B02, 2014CB643600) and NSFC(21574140).

  6. Flowing in group field theory space: a review

    CERN Document Server

    Carrozza, Sylvain

    2016-01-01

    We provide a non--technical overview of recent extensions of renormalization methods and techniques to Group Field Theories (GFTs), a class of combinatorially non--local quantum field theories which generalize matrix models to dimension $d \\geq 3$. More precisely, we focus on GFTs with so--called closure constraint, which are closely related to lattice gauge theories and quantum gravity spin foam models. With the help of modern tensor model tools, a rich landscape of renormalizable theories has been unravelled. We review our current understanding of their renormalization group flows, at both perturbative and non--perturbative levels.

  7. Role of uniform horizontal magnetic field on convective flow

    CERN Document Server

    Pal, Pinaki; 10.1140/epjb/e2012-30048-8

    2013-01-01

    The effect of uniform magnetic field applied along a fixed horizontal direction in Rayleigh-B\\'enard convection in low-Prandtl-number fluids has been studied using a low dimensional model. The model shows the onset of convection (primary instability) in the form of two dimensional stationary rolls in the absence of magnetic field, when the Rayleigh number $R$ is raised above a critical value $R_c$. The flow becomes three dimensional at slightly higher values of Rayleigh number via wavy instability. These wavy rolls become chaotic for slightly higher values of $R$ in low-Prandtl-number ($P_r$) fluids. A uniform magnetic field along horizontal plane strongly affects all kinds of convective flows observed at higher values of $R$ in its absence. As the magnetic field is raised above certain value, it orients the convective rolls in its own direction. Although the horizontal magnetic field does not change the threshold for the primary instability, it affects the threshold for secondary (wavy) instability. It inhib...

  8. Cutting risk, boosting cash flow and developing marginal fields

    International Nuclear Information System (INIS)

    To minimize financial risk and accelerate return on investment, oil companies are using low-cost, reusable production systems. The scope of these development options is illustrated by looking at three offshore case studies that range from extended well test to marginal field development. In each case, production systems technology has been deployed to provide superior data, early oil or both, thus reducing economic uncertainty and delivering accelerated cash flow. 10 figs., 23 refs

  9. An Efficient Procedure for Viscous Propeller Flow Field Calculations

    OpenAIRE

    Boyle, Fergal

    2002-01-01

    An efficient procedure has been developed for the computation of the three-dimensional, compressible, viscous flow field around a general propeller geometry with the inflow at zero angles of incidence and yaw. The solution procedure combines a recently developed Reynolds-Averaged-Navier-Stokes equations solver with a commercially available grid generator designed specifically for turbomachinery configurations. Preliminary results from the calculation of laminar and turbulent incompressible fl...

  10. ARLearn: augmented reality meets augmented virtuality

    NARCIS (Netherlands)

    Ternier, Stefaan; Klemke, Roland; Kalz, Marco; Van Ulzen, Patricia; Specht, Marcus

    2012-01-01

    Ternier, S., Klemke, R., Kalz, M., Van Ulzen, P., & Specht, M. (2012). ARLearn: augmented reality meets augmented virtuality [Special issue]. Journal of Universal Computer Science - Technology for learning across physical and virtual spaces, 18(15), 2143-2164.

  11. Light field optical flow for refractive surface reconstruction

    Science.gov (United States)

    Iffa, Emishaw; Wetzstein, Gordon; Heidrich, Wolfgang

    2012-10-01

    This paper discusses a method to reconstruct a transparent ow surface from single camera shot with the aid of a Micro-lens array. An intentionally prepared high frequency background which is placed behind the refractive flow is captured and a curl-free optical flow algorithm is applied between pairs of images taken by different micro-lenses. The computed raw optical ow vector is a blend of motion parallax and background deformation vector due to the underlying flow. Subtracting the motion parallax, which is obtained by calibration, from the total op- optical flow vector yields the background deformation vector. The deflection vectors on each images are used to reconstruct the flow profile. A synthetic data set of fuel injection was used to evaluate the accuracy of the proposed algorithm and good agreement was achieved between the test and reconstructed data. Finally, real light field data of hot air created by a lighter flame is used to reconstruct and show a hot air plume surface.

  12. Kinetic simulation of rarefied and weakly ionized hypersonic flow fields

    Science.gov (United States)

    Farbar, Erin D.

    When a vehicle enters the Earth's atmosphere at the very large velocities associated with Lunar and Mars return, a strong bow shock is formed in front of the vehicle. The shock heats the air to very high temperatures, causing collisions that are sufficiently energetic to produce ionized particles. As a result, a weakly ionized plasma is formed in the region between the bow shock and the vehicle surface. The presence of this plasma impedes the transport of radio frequency waves to the vehicle, causing the phenomenon known as "communications black out". The plasma also interacts with the neutral particles in the flow field, and contributes to the heat flux at the vehicle surface. Since it is difficult to characterize these flow fields using flight or ground based experiments, computational tools play an important role in the design of reentry vehicles. It is important to include the physical phenomena associated with the presence of the plasma in the computational analysis of the flow fields about these vehicles. Physical models for the plasma phenomena are investigated using a state of the art, Direct Simulation Monte Carlo (DSMC) code. Models for collisions between charged particles, plasma chemistry, and the self-induced electric field that currently exist in the literature are implemented. Using these baseline models, steady state flow field solutions are computed for the FIRE II reentry vehicle at two different trajectory points. The accuracy of each baseline plasma model is assessed in a systematic fashion, using one flight condition of the FIRE II vehicle as the test case. Experimental collision cross section data is implemented to model collisions of electrons with neutral particles. Theoretical and experimental reaction cross section data are implemented to model chemical reactions that involve electron impact, and an associative ionization reaction. One-dimensional Particle-In-Cell (PIC) routines are developed and coupled to the DSMC code, to assess the

  13. Modeling field scale unsaturated flow and transport processes

    International Nuclear Information System (INIS)

    The scales of concern in subsurface transport of contaminants from low-level radioactive waste disposal facilities are in the range of 1 to 1,000 m. Natural geologic materials generally show very substantial spatial variability in hydraulic properties over this range of scales. Such heterogeneity can significantly influence the migration of contaminants. It is also envisioned that complex earth structures will be constructed to isolate the waste and minimize infiltration of water into the facility. The flow of water and gases through such facilities must also be a concern. A stochastic theory describing unsaturated flow and contamination transport in naturally heterogeneous soils has been enhanced by adopting a more realistic characterization of soil variability. The enhanced theory is used to predict field-scale effective properties and variances of tension and moisture content. Applications illustrate the important effects of small-scale heterogeneity on large-scale anisotropy and hysteresis and demonstrate the feasibility of simulating two-dimensional flow systems at time and space scales of interest in radioactive waste disposal investigations. Numerical algorithms for predicting field scale unsaturated flow and contaminant transport have been improved by requiring them to respect fundamental physical principles such as mass conservation. These algorithms are able to provide realistic simulations of systems with very dry initial conditions and high degrees of heterogeneity. Numerical simulation of the movement of water and air in unsaturated soils has demonstrated the importance of air pathways for contaminant transport. The stochastic flow and transport theory has been used to develop a systematic approach to performance assessment and site characterization. Hypothesis-testing techniques have been used to determine whether model predictions are consistent with observed data

  14. Field-Flow Fractionation of Carbon Nanotubes and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    John P. Selegue

    2011-11-17

    During the grant period, we carried out FFF studies of carbonaceous soot, single-walled and multi-walled carbon nanotubes, carbon nano-onions and polyoxometallates. FFF alone does not provide enough information to fully characterize samples, so our suite of characterization techniques grew to include light scattering (especially Photon Correlation Spectroscopy), scanning and transmission electron microscopy, thermogravimetric analysis and spectroscopic methods. We developed convenient techniques to deposit and examine minute FFF fractions by electron microscopy. In collaboration with Arthur Cammers (University of Kentucky), we used Flow Field-Flow Fractionation (Fl-FFF) to monitor the solution-phase growth of keplerates, a class of polyoxometallate (POM) nanoparticles. We monitored the evolution of Mo-POM nanostructures over the course of weeks by by using flow field-flow fractionation and corroborated the nanoparticle structures by using transmission electron microscopy (TEM). Total molybdenum in the solution and precipitate phases was monitored by using inductively coupled plasma analyses, and total Mo-POM concentration by following the UV-visible spectra of the solution phase. We observe crystallization-driven formation of (Mo132) keplerate and solution phase-driven evolution of structurally related nanoscopic species (3-60 nm). FFF analyses of other classes of materials were less successful. Attempts to analyze platelets of layered materials, including exfoliated graphite (graphene) and TaS2 and MoS2, were disappointing. We were not able to optimize flow conditions for the layered materials. The metal sulfides react with the aqueous carrier liquid and settle out of suspension quickly because of their high density.

  15. Prolonged Low Flow Reduces Reactive Hyperemia and Augments Low Flow Mediated Constriction in the Brachial Artery Independent of the Menstrual Cycle

    OpenAIRE

    Mark Rakobowchuk; Emily R Parsloe; Sarah E Gibbins; Emma Harris; Karen M Birch

    2013-01-01

    © 2013 Rakobowchuk et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Non-invasive forearm ischemia-reperfusion injury and low flow induced vascular dysfunction models provide methods to evaluate vascular function. The role of oestrogen, an endogenous anti-oxidant on recovery from ischemia-reperfus...

  16. Flow downstream of the heliospheric terminal shock - Magnetic field kinematics

    Science.gov (United States)

    Nerney, S.; Suess, S. T.; Schmahl, E. J.

    1991-01-01

    A kinematic model of the interplanetary magnetic field in the heliosheath beyond the solar wind terminal shock is presented in order to evaluate the possible importance of MHD effects in that region of space. The need for this evaluation arises because the interplanetary magnetic field is compressed across the terminal shock and further amplified by the decreasing flow speed beyond the shock. Streamlines which approach the stagnation point before turning in the downstream direction lead to the strongest effects due to the extreme slowing of the solar wind and consequent compression of the embedded magnetic field. The magnetic volume force therefore cannot be neglected on streamlines that approach the heliopause in the upstream direction, where the volume containing them is a large fraction of the overall of the heliosheath in the upstream direction. The increase in the magnetic pressure may act to bring the upstream terminal shock significantly closer to the sun, potentially reconciling a conflict between models and observations.

  17. The 3D Flow Field Around an Embedded Planet

    Science.gov (United States)

    Fung, Jeffrey; Artymowicz, Pawel; Wu, Yanqin

    2015-10-01

    3D modifications to the well-studied 2D flow topology around an embedded planet have the potential to resolve long-standing problems in planet formation theory. We present a detailed analysis of the 3D isothermal flow field around a 5 Earth-mass planet on a fixed circular orbit, simulated using our graphics processing unit hydrodynamics code PEnGUIn. We find that, overall, the horseshoe region has a columnar structure extending vertically much beyond the Hill sphere of the planet. This columnar structure is only broken for some of the widest horseshoe streamlines, along which high altitude fluid descends rapidly into the planet’s Bondi sphere, performs one horseshoe turn, and exits the Bondi sphere radially in the midplane. A portion of this flow exits the horseshoe region altogether, which we refer to as the “transient” horseshoe flow. The flow continues as it rolls up into a pair of up-down symmetric horizontal vortex lines shed into the wake of the planet. This flow, unique to 3D, affects both planet accretion and migration. It prevents the planet from sustaining a hydrostatic atmosphere due to its intrusion into the Bondi sphere, and leads to a significant corotation torque on the planet, unanticipated by 2D analysis. In the reported simulation, starting with a {{Σ }}˜ {r}-3/2 radial surface density profile, this torque is positive and partially cancels with the negative differential Lindblad torque, resulting in a factor of three slower planet migration rate. Finally, we report 3D effects can be suppressed by a sufficiently large disk viscosity, leading to results similar to 2D.

  18. Numerical Investigation Of Surface Roughness Effects On The Flow Field In A Swirl Flow

    Directory of Open Access Journals (Sweden)

    Ali SAKİN

    2014-12-01

    Full Text Available The aim of this study is to investigate axial and tangential velocity profiles, turbulent dissipation rate, turbulent kinetic energy and pressure losses under the influence of surface roughness for the swirling flow in a cyclone separator. The governing equations for this flow were solved by using Fluent CFD code. First, numerical analyses were run to verify numerical solution and domain with experimental results. Velocity profiles, turbulent parameters and pressure drops were calculated by increasing inlet velocity from 10 to 20 m/s and roughness height from 0 to 4 mm. Analyses of results showed that pressure losses are decreased and velocity field is considerably affected by increasing roughness height.

  19. Improved Flow-Field Structures for Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gurau, Bogdan

    2013-05-31

    The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.

  20. Different elution modes and field programming in gravitational field-flow fractionation. III. Field programming by flow-rate gradient generated by a programmable pump.

    Science.gov (United States)

    Plocková, J; Chmelík, J

    2001-05-25

    Gravitational field-flow fractionation (GFFF) utilizes the Earth's gravitational field as an external force that causes the settlement of particles towards the channel accumulation wall. Hydrodynamic lift forces oppose this action by elevating particles away from the channel accumulation wall. These two counteracting forces enable modulation of the resulting force field acting on particles in GFFF. In this work, force-field programming based on modulating the magnitude of hydrodynamic lift forces was implemented via changes of flow-rate, which was accomplished by a programmable pump. Several flow-rate gradients (step gradients, linear gradients, parabolic, and combined gradients) were tested and evaluated as tools for optimization of the separation of a silica gel particle mixture. The influence of increasing amount of sample injected on the peak resolution under flow-rate gradient conditions was also investigated. This is the first time that flow-rate gradients have been implemented for programming of the resulting force field acting on particles in GFFF. PMID:11407583

  1. Flow rate estimation using acoustic field distortions caused by turbulent flows: time-reversal approach

    Science.gov (United States)

    Zimmermann, A. L.; Pérez, N.; Adamowski, J. C.

    2011-05-01

    A new acoustic technique for flow rate estimation is proposed here. This technique is based on the traditional ultrasonic cross-correlation flow meter, but instead of using a continuous wave or pulse trains in each transmitter-receiver pair, the acoustic time-reversal technique is applied. The system relies on the principle that a turbulent flow with multiple vortices will cause random distortions in a given acoustic field; hence, analyzing this noise caused in the ultrasound signal by the turbulence over time allows a "signature" or "tag" of the flow to be defined. In other words, the vortices modify the frequency response function of the flowing system uniquely, since the distortion is assumed to be random. The use of the time-reversal procedure in the cross-correlation flow meter provides improvements in several aspects: it simplifies the signal processing needed after the reception of the signals, avoiding the use of a demodulator to obtain the signature of the vortex; the signal is focused at the position of the reception transducer and; the sensitivity is also increased because the wave travels twice in the acoustic channel. The method is theoretically discussed showing its limitations and improvements. Experimental results in a laboratory water tank are also presented.

  2. Effect of Impeller Geometry and Tongue Shape on the Flow Field of Cross Flow Fans

    Institute of Scientific and Technical Information of China (English)

    M. Govardhan; G. Venkateswarlu

    2003-01-01

    Experiments were conducted to investigate the effect of impeller geometry and tongue shape on the flow field of cross flow fans.Three impellers (Ⅰ,Ⅱ,Ⅲ)having same outer diameter,but different radius ratio and blade angles were employed for the investigation. Each impeller was tested with two tongue shapes. Flow survey was carded out for each impeller and tongue shape at two flow coefficients, and for each flow coefficient at different circumferential positions. The flow is two-dimensional along the blade span except near the shrouds.The total pressure developed by the impellers in each case is found to be maximum at a circumferential position of around 270°. The total and static pressures at the inlet of impellers are more or less same regardless of impeller and tongue geometry, but they vary considerably at exit of the impellers. Impeller Ⅲ with tongue T2 develops higher total pressure and efficiency where as impeller Ⅱ with tongue T_2 develops minimum total pressure.Higher diffusion and smaller vortex size are the reasons for better performance of impeller Ⅲ with tongue T2.

  3. Horizontal flow fields observed in Hinode G-band images. II. Flow fields in the final stages of sunspot decay

    Science.gov (United States)

    Verma, M.; Balthasar, H.; Deng, N.; Liu, C.; Shimizu, T.; Wang, H.; Denker, C.

    2012-02-01

    Context. Generation and dissipation of magnetic fields is a fundamental physical process on the Sun. In comparison to flux emergence and the initial stages of sunspot formation, the demise of sunspots still lacks a comprehensive description. Aims: The evolution of sunspots is most commonly discussed in terms of their intensity and magnetic field. Here, we present additional information about the three-dimensional flow field in the vicinity of sunspots towards the end of their existence. Methods: We present a subset of multi-wavelengths observations obtained with the Japanese Hinode mission, the Solar Dynamics Observatory (SDO), and the Vacuum Tower Telescope (VTT) at Observatorio del Teide, Tenerife, Spain during the time period 2010 November 18-23. Horizontal proper motions were derived from G-band and Ca ii H images, whereas line-of-sight velocities were extracted from VTT echelle Hα λ656.28 nm spectra and Fe i λ630.25 nm spectral data of the Hinode/Spectro-Polarimeter, which also provided three-dimensional magnetic field information. The Helioseismic and Magnetic Imager on board SDO provided continuum images and line-of-sight magnetograms, in addition to the high-resolution observations for the entire disk passage of the active region. Results: We perform a quantitative study of photospheric and chromospheric flow fields in and around decaying sunspots. In one of the trailing sunspots of active region NOAA 11126, we observe moat flow and moving magnetic features (MMFs), even after its penumbra had decayed. We also detect a superpenumbral structure around this pore. We find that MMFs follow well-defined, radial paths from the spot all the way to the border of a supergranular cell surrounding the spot. In contrast, flux emergence near the other sunspot prevents the establishment of similar well ordered flow patterns, which could be discerned around a tiny pore of merely 2 Mm diameter. After the disappearance of the sunspots/pores, a coherent patch of abnormal

  4. Hybrid approach to uncertainty in far-field groundwater flow

    International Nuclear Information System (INIS)

    The quantification of far-field groundwater flow uncertainty is a critical issue regarding site selection for a geologic high-level nuclear waste repository. A nonlinear relationship between geohydrologic parameters (e.g., hydraulic conductivity, potentiometric head, effective porosity) and repository performance measures (e.g., groundwater travel paths or travel times) induces an extremely complex input/output variable response. A hybrid approach involving geostatistics (kriging), adjoint sensitivity, parameter-identification, first-order variance, and Monte Carlo simulation is proposed to determine groundwater flow system uncertainty. The techniques are currently being applied to help select new borehole locations for the site characterization phase of the salt formation investigations by the Salt Repository Project of Nuclear Waste. Preliminary results are presented from two-dimensional simulations of the Wolfcamp Formation within the Permian system

  5. CFD analysis of flow field in a triangular rod bundle

    International Nuclear Information System (INIS)

    The flow field was investigated in subchannels of VVER-440 pressurized water cooled reactors' fuel assemblies (triangular lattice, P/D = 1.35). Impacts of the mesh resolution and turbulence model were studied in order to obtain guidelines for CFD calculations of VVER-440 rod bundles. Results were compared to measurement data published by Trupp and Azad in 1975. The study pointed out that RANS method with BSL Reynolds stress model using a sufficient fine grid can provide an accurate prediction for the turbulence quantities in this lattice. Applying the experiences of the sensitivity study thermal hydraulic processes were investigated in VVER-440 rod bundle sections. Based on the examinations the spacer grids have important effects on the cross flows, axial velocity and outlet temperature distribution of subchannels therefore they have to be modeled satisfactorily in CFD calculations.

  6. Mean-Field Description of Plastic Flow in Amorphous Solids

    Science.gov (United States)

    Lin, Jie; Wyart, Matthieu

    2016-01-01

    Failure and flow of amorphous materials are central to various phenomena including earthquakes and landslides. There is accumulating evidence that the yielding transition between a flowing and an arrested phase is a critical phenomenon, but the associated exponents are not understood, even at a mean-field level where the validity of popular models is debated. Here, we solve a mean-field model that captures the broad distribution of the mechanical noise generated by plasticity, whose behavior is related to biased Lévy flights near an absorbing boundary. We compute the exponent θ characterizing the density of shear transformation P (x )˜xθ, where x is the stress increment beyond which they yield. We find that after an isotropic thermal quench, θ =1 /2 . However, θ depends continuously on the applied shear stress; this dependence is not monotonic, and its value at the yield stress is not universal. The model rationalizes previously unexplained observations and captures reasonably well the value of exponents in three dimensions. Values of exponents in four dimensions are accurately predicted. These results support the fact that it is the true mean-field model that applies in large dimensions, and they raise fundamental questions about the nature of the yielding transition.

  7. Axial Magnetic Field Effect on Taylor-Couette Flow

    Directory of Open Access Journals (Sweden)

    Sofiane ABERKANE

    2015-01-01

    Full Text Available This study is interested in the effect of an axial magnetic field imposed on incompressible flow of electrically conductive fluid between two horizontal coaxial cylinders. The imposed magnetic field is assumed uniform and constant. The effect of heat generation due to viscous dissipation is also taken into account. The inner and outer cylinders are maintained at different uniform temperatures. The movement of the fluid is due to rotation of the cylinder with a constant speed. An exact solution of the equations governing the flow was obtained in the form of Bessel functions. A finite difference implicit scheme was used in the numerical solution. The velocity and temperature distributions were obtained with and without the magnetic field. The results show that for different values of the Hartmann number, the velocity between the two cylinders decreases as the Hartmann number increases. Also, it is found that by increasing the Hartmann number, the average Nusselt number decreases. On the other hand, the Hartmann number does not affect the temperature.

  8. Numerical realization of flow field by integrating computation and measurement

    International Nuclear Information System (INIS)

    In this paper we propose a concept of numerical realization, namely, simulations in real conditions, in order to distinguish their inherent difficulties as well as their importance in comparison with those of ordinary simulations. An important property of numerical simulations is that analysis can be performed under arbitrarily specified conditions. Investigation using various parameters reveals the structure or the internal relationships of the phenomena, and thus, numerical simulation has been taking the place of the experimental approach to design problems in a wide variety of fields. On the other hand, analysis in real conditions is another important objective of numerical simulation. lt provides information on the internal states of the relevant phenomena, which is essential in control problems in a wide sense. lt should be emphasized that this is not a trivial issue, especially for field problems such as flow systems because of the difficulty in determining the conditions. For example, the number of boundary conditions to be specified is on the order of n2 for a 3-D problem with n3 grid points. lt is apparently unrealistic to measure all the boundary values so as to include every possible disturbance on the boundary. Observability and controllability in dynamic system theory should be the key concepts in simulations in real conditions, or numerical realization. For observable and controllable dynamical systems of relatively small orders, a theoretical framework has been established in which an observer has been designed to enable conceptualization of the whole state from observation of a few output variables. The concept of observer can be applied to the numerical realization of flow field. First, a finite number of output variables are so defined that measurement is possible and the system satisfies the observability condition. Then a number of inputs are defined in the numerical simulation as the boundary conditions or the body force in the domain. The

  9. Resist deformation and flow fields in microimprint lithography

    International Nuclear Information System (INIS)

    In microimprint lithography, the resist deformation directly influences the quality of the final imprinted patterns. The resist velocity field was investigated through numerical simulations and visualization experiments. A numerical model based on the computational fluid dynamics was built to predict the resist filling behavior. Meanwhile, a 3D defocusing digital particle image velocimetry (DDPIV) system was developed to achieve the microscale velocity field of resist. The spatial coordinates of the fluorescent tracer particles were derived from their defocused images, and then the three-dimensional particle field and velocity field inside the resist were obtained according to the particles' spatial coordinates and time interval recording the particle images. The investigation of the velocity field, including the horizontal and vertical velocity history, was performed to help describe the filling mode and flow behavior of the resist. The experimental results agreed well with the simulation prediction, which justified the use of the micro DDPIV system to investigate the resist filling behavior and verified the numerical model. The combined effect of the mold's local asymmetric geometries and resist's initial thickness on its own deformation was further analyzed by numerical simulation. (paper)

  10. Magnetohydrodynamic Ekman layers with field-aligned flow

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, Manuel, E-mail: mnjmhd@am.uva.es [Departamento de Analisis Matematico, Universidad de Valladolid, 47005 Valladolid (Spain)

    2011-05-01

    The Ekman layer in a conducting fluid with constant angular velocity, provided with a magnetic field aligned with the flow, is studied here. The existence of solutions to the magnetohydrodynamic linearized equations depends on the balance between viscosity and resistivity, on the one hand, and the angular and Alfven velocities, on the other. In most cases, exponentially decreasing solutions exist, although their longitudinal oscillations do not need to be periodic. One of the instances without a solution is explained by the presence of Alfven waves traveling backwards along the streamlines.

  11. Verifying a Simplified Fuel Oil Flow Field Measurement Protocol

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, H.; Dentz, J.; Doty, C.

    2013-07-01

    The Better Buildings program is a U.S. Department of Energy program funding energy efficiency retrofits in buildings nationwide. The program is in need of an inexpensive method for measuring fuel oil consumption that can be used in evaluating the impact that retrofits have in existing properties with oil heat. This project developed and verified a fuel oil flow field measurement protocol that is cost effective and can be performed with little training for use by the Better Buildings program as well as other programs and researchers.

  12. Real gas flow fields about three dimensional configurations

    Science.gov (United States)

    Balakrishnan, A.; Lombard, C. K.; Davy, W. C.

    1983-01-01

    Real gas, inviscid supersonic flow fields over a three-dimensional configuration are determined using a factored implicit algorithm. Air in chemical equilibrium is considered and its local thermodynamic properties are computed by an equilibrium composition method. Numerical solutions are presented for both real and ideal gases at three different Mach numbers and at two different altitudes. Selected results are illustrated by contour plots and are also tabulated for future reference. Results obtained compare well with existing tabulated numerical solutions and hence validate the solution technique.

  13. Flow and Temperature Fields in Slab Continuous Casting Molds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to develop super-board and super-thick slabs, the flow and temperature fields were studied in slab continuous casting molds under different practical conditions, such as slab dimensions, with-drawing slab speed, design of nozzles, and superheat temperature. The results showed that it is preferred to incline nozzle bores downwards and the submerged depth of the nozzles is best kept between 250€?300 mm. In addition, the solidified shell is thicker at the wide face than that at the narrow face, while the thin points along the wide face exist both in the center and in the some area toward each respective end.

  14. Magnetic field effect on fluid flow characteristics in a pipe for laminar flow

    International Nuclear Information System (INIS)

    The influence of a magnetic field on the skin friction factor of steady fully-developed laminar flow through a pipe was studied experimentally. A mathematical model was introduced and a finite difference scheme used to solve the governing equations in terms of vorticity- stream function. The model predictions agree favourably with experimental results. It is observed that the pressure drop varies in proportion to the square of the product of the magnetic field and the sine of the magnetic field angle. Also, the pressure drop is proportional to the flow rate. This situation is similar to what applies in the absence of a magnetic field. It is found that a transverse magnetic field changes the axial velocity profile from the parabolic to a relatively flat shape. At first, the radial velocity rises more rapidly and then gradually decreases along the pipe until falling to zero. A numerical correlation can be written for the considerable distance required for the new axial velocity profile to establish. Owing to the changes taking place in the axial velocity profile, it exhibits a higher skin friction factor. The new axial velocity profile asymptotically approaches its limit as the Hartmann number becomes large

  15. Augmented Reality in Astrophysics

    OpenAIRE

    Vogt, Frédéric P. A.; Shingles, Luke J.

    2013-01-01

    Augmented Reality consists of merging live images with virtual layers of information. The rapid growth in the popularity of smartphones and tablets over recent years has provided a large base of potential users of Augmented Reality technology, and virtual layers of information can now be attached to a wide variety of physical objects. In this article, we explore the potential of Augmented Reality for astrophysical research with two distinct experiments: (1) Augmented Posters and (2) Augmented...

  16. Review of passive heat transfer augmentation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Dewan, A.; Mahanta, P.; Sumithra Raju, K. [Indian Institute of Technology, Guwahati (India). Dept. of Mechanical Engineering; Suresh Kumar, P. [Indian Institute of technology, Kharagpur (India). Dept. of Oocean Engineering and Naval Architecture

    2004-12-01

    Heat transfer augmentation techniques (passive, active or a combination of passive and active methods) are commonly used in areas such as process industries, heating and cooling in evaporators, thermal power plants, air- conditioning equipment, refrigerators, radiators for space vehicles, automobiles, etc. Passive techniques, where inserts are used in the flow passage to augment the heat transfer rate, are advantageous compared with active techniques, because the insert manufacturing process is simple and these techniques can be easily employed in an existing heat exchanger. In design of compact heat exchangers, passive techniques of heat transfer augmentation can play an important role if a proper passive insert configuration can be selected according to the heat exchanger working condition (both flow and heat transfer conditions). In the past decade, several studies on the passive techniques of heat transfer augmentation have been reported. The present paper is a review on progress with the passive augmentation techniques in the recent past and will be useful to designers implementing passive augmentation techniques in heat exchange. Twisted tapes, wire coils, ribs, fins, dimples, etc., are the most commonly used passive heat transfer augmentation tools. In the present paper, emphasis is given to works dealing with twisted tapes and wire coils because, according to recent studies, these are known to be economic heat transfer augmentation tools. The former insert is found to be suitable in a laminar flow regime and the latter is suitable for turbulent flow. The thermohydraulic behaviour of an insert mainly depends on the flow conditions (laminar or turbulent) apart from the insert configurations. The present review is organized in five different sections: twisted tape in laminar flow; twisted tape in turbulent flow; wire coil in laminar flow; wire coil in turbulent flow; other inserts such as ribs, fins, dimples, etc. (author)

  17. Hyphenation of Field-Flow Fractionation and Magnetic Particle Spectroscopy

    Directory of Open Access Journals (Sweden)

    Norbert Löwa

    2015-11-01

    Full Text Available Magnetic nanoparticles (MNPs exhibit unique magnetic properties making them ideally suited for a variety of biomedical applications. Depending on the desired magnetic effect, MNPs must meet special magnetic requirements which are mainly determined by their structural properties (e.g., size distribution. The hyphenation of chromatographic separation techniques with complementary detectors is capable of providing multidimensional information of submicron particles. Although various methods have already been combined for this approach, so far, no detector for the online magnetic analysis was used. Magnetic particle spectroscopy (MPS has been proven a straightforward technique for specific quantification and characterization of MNPs. It combines high sensitivity with high temporal resolution; both of these are prerequisites for a successful hyphenation with chromatographic separation. We demonstrate the capability of MPS to specifically detect and characterize MNPs under usually applied asymmetric flow field-flow fractionation (A4F conditions (flow rates, MNP concentration, different MNP types. To this end MPS has been successfully integrated into an A4F multidetector platform including dynamic ligth scattering (DLS, multi-angle light scattering (MALS and ultraviolet (UV detection. Our system allows for rapid and comprehensive characterization of typical MNP samples for the systematic investigation of structure-dependent magnetic properties. This has been demonstrated by magnetic analysis of the commercial magnetic resonance imaging (MRI contrast agent Ferucarbotran (FER during hydrodynamic A4F fractionation.

  18. Control of Flowing Liquid Films by Electrostatic Fields in Space

    Science.gov (United States)

    Griffing, E. M.; Bankoff, S. G.; Schluter, R. A.; Miksis, M. J.

    1999-01-01

    The interaction of a spacially varying electric field and a flowing thin liquid film is investigated experimentally for the design of a proposed light weight space radiator. Electrodes are utilized to create a negative pressure at the bottom of a fluid film and suppress leaks if a micrometeorite punctures the radiator surface. Experimental pressure profiles under a vertical falling film, which passes under a finite electrode, show that fields of sufficient strength can be used safely in such a device. Leak stopping experiments demonstrate that leaks can be stopped with an electric field in earth gravity. A new type of electrohydrodynamic instability causes waves in the fluid film to develop into 3D cones and touch the electrode at a critical voltage. Methods previously used to calculate critical voltages for non moving films are shown to be inappropriate for this situation. The instability determines a maximum field which may be utilized in design, so the possible dependence of critical voltage on electrode length, height above the film, and fluid Reynolds number is discussed.

  19. Fast wave power flow along SOL field lines in NSTX

    Science.gov (United States)

    Perkins, R. J.; Bell, R. E.; Diallo, A.; Gerhardt, S.; Hosea, J. C.; Jaworski, M. A.; Leblanc, B. P.; Kramer, G. J.; Phillips, C. K.; Roquemore, L.; Taylor, G.; Wilson, J. R.; Ahn, J.-W.; Gray, T. K.; Green, D. L.; McLean, A.; Maingi, R.; Ryan, P. M.; Jaeger, E. F.; Sabbagh, S.

    2012-10-01

    On NSTX, a major loss of high-harmonic fast wave (HHFW) power can occur along open field lines passing in front of the antenna over the width of the scrape-off layer (SOL). Up to 60% of the RF power can be lost and at least partially deposited in bright spirals on the divertor floor and ceiling [1,2]. The flow of HHFW power from the antenna region to the divertor is mostly aligned along the SOL magnetic field [3], which explains the pattern of heat deposition as measured with infrared (IR) cameras. By tracing field lines from the divertor back to the midplane, the IR data can be used to estimate the profile of HHFW power coupled to SOL field lines. We hypothesize that surface waves are being excited in the SOL, and these results should benchmark advanced simulations of the RF power deposition in the SOL (e.g., [4]). Minimizing this loss is critical optimal high-power long-pulse ICRF heating on ITER while guarding against excessive divertor erosion.[4pt] [1] J.C. Hosea et al., AIP Conf Proceedings 1187 (2009) 105. [0pt] [2] G. Taylor et al., Phys. Plasmas 17 (2010) 056114. [0pt] [3] R.J. Perkins et al., to appear in Phys. Rev. Lett. [0pt] [4] D.L. Green et al., Phys. Rev. Lett. 107 (2011) 145001.

  20. Residence time measurement of an isothermal combustor flow field

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Liangta; Spencer, Adrian [Loughborough University, Department of Aero and Auto Engineering, Loughborough (United Kingdom)

    2012-03-15

    Residence times of combustors have commonly been used to help understand NO{sub x} emissions and flame blowout. Both the time mean velocity and turbulence fields are important to the residence time, but determining the residence time via analysis of a measured velocity field is difficult due to the inherent unsteadiness and the three-dimensional nature of a high-Re swirling flow. A more direct approach to measure residence time is reported here that examines the dynamic response of fuel concentration to a sudden cutoff in the fuel injection. Residence time measurement was mainly taken using a time-resolved planar laser-induced fluorescence (PLIF) technique, but a second camera for particle image velocimetry (PIV) was added to check that the step change does not alter the velocity field and the spectral content of the coherent structures. Characteristic timescales evaluated from the measurements are referred to as convection and half-life times: The former describes the time delay from a fuel injector exit reference point to a downstream point of interest, and the latter describes the rate of decay once the effect of the reduced scalar concentration at the injection source has been transported to the point of interest. Residence time is often defined as the time taken for a conserved scalar to reduce to half its initial value after injection is stopped: this equivalent to the sum of the convection time and the half-life values. The technique was applied to a high-swirl fuel injector typical of that found in combustor applications. Two test cases have been studied: with central jet (with-jet) and without central jet (no-jet). It was found that the relatively unstable central recirculation zone of the no-jet case resulted in increased transport of fuel into the central region that is dominated by a precessing vortex core, where long half-life times are also found. Based on this, it was inferred that the no-jet case may be more prone to NO{sub x} production. The

  1. The Flow Field Analysis and Flow Calculation of Ultrasonic Flowmeter Based on the Fluent Software

    Directory of Open Access Journals (Sweden)

    Ling Guo

    2014-01-01

    Full Text Available We can build the three-dimensional structure model based on the Gambit software and achieve the distribution of flow field in the pipe and reflux flow condition at the position of transducer in regard to the real position of transducer according to the Fluent software. Under the framework, define the reflux length based on the distance of reflux along the channel and evaluate the effect of reflux on flow field. Then we can correct the power factor with the transmission speed difference method in the ideal condition and obtain the matching expression of power correction factor according to the practice model. In the end, analyze the simulation experience and produce the sample table based on the proposed model. The comparative analysis of test results and simulation results demonstrates the validity and feasibility of the proposed simulation method. The research in this paper will lay a foundation for further study on the optimization of ultrasonic flowmeter, enhance the measurement precision, and extend the application of engineering.

  2. Conductivity-Dependent Flow Field-Flow Fractionation of Fulvic and Humic Acid Aggregates

    Directory of Open Access Journals (Sweden)

    Martha J. M. Wells

    2015-09-01

    Full Text Available Fulvic (FAs and humic acids (HAs are chemically fascinating. In water, they have a strong propensity to aggregate, but this research reveals that tendency is regulated by ionic strength. In the environment, conductivity extremes occur naturally—freshwater to seawater—warranting consideration at low and high values. The flow field flow fractionation (flow FFF of FAs and HAs is observed to be concentration dependent in low ionic strength solutions whereas the corresponding flow FFF fractograms in high ionic strength solutions are concentration independent. Dynamic light scattering (DLS also reveals insight into the conductivity-dependent behavior of humic substances (HSs. Four particle size ranges for FAs and humic acid aggregates are examined: (1 <10 nm; (2 10 nm–6 µm; (3 6–100 µm; and (4 >100 µm. Representative components of the different size ranges are observed to dynamically coexist in solution. The character of the various aggregates observed—such as random-extended-coiled macromolecules, hydrogels, supramolecular, and micellar—as influenced by electrolytic conductivity, is discussed. The disaggregation/aggregation of HSs is proposed to be a dynamic equilibrium process for which the rate of aggregate formation is controlled by the electrolytic conductivity of the solution.

  3. Experimental Investigation of the Flow Field in a Multistage Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    B. Lakshminarayana

    1996-01-01

    Full Text Available The nature of the flow field in a three stage axial flow compressor, including a detailed survey at the exit of an embedded stator as well as the overall performance of the compressor is presented and interpreted in this paper. The measurements include area traverse of a miniature five hole probe (1.07 mm dia downstream of stator 2, radial traverses of a miniature five hole probe at the inlet, downstream of stator 3 and at the exit of the compressor at various circumferential locations, area traverse of a low response thermocouple probe downstream of stator 2, radial traverses of a single sensor hot-wire probe at the inlet, and casing static pressure measurements at various circumferential and axial locations across the compressor at the peak efficiency operating point. Mean velocity, pressure and total temperature contours as well as secondary flow contours at the exit of the stator 2 are reported and interpreted. Secondary flow contours show the migration of fluid particles toward the core of the low pressure regions located near the suction side casing endwall corner.

  4. Multi-phase flow effect on SRM nozzle flow field and thermal protection materials

    Institute of Scientific and Technical Information of China (English)

    SHAFQAT Wahab; XIE Kan; LIU Yu

    2009-01-01

    Multi-phase flow effect generated from the combustion of aluminum based com-posite propellant was performed on the thermal protection material of solid rocket motor (SRM) nozzle. Injection of alumina (Al2O3) particles from 5% to 10% was tried on SRM nozzle flow field to see the influence of multiphase flow on heat transfer computations. A coupled, time resolved CFD (computational fluid dynamics) approach was adopted to solve the conjugate problem of multi-phase fluid flow and heat transfer in the solid rocket motor nozzle. The governing equations are discretized by using the finite volume method. Spalart-Allmaras (S-A) turbulence model was employed. The computation was executed on the dif-ferent models selected for the analysis to validate the temperature variation in the throat in-serts and baking material of SRM nozzle. Comparison for temperatures variations were also carried out at different expansion ratios of nozzle. This paper also characterized the advanced SRM nozzle composites material for their high thermo stability and their high thermo me-chanical capabilities to make it more reliable simpler and lighter.

  5. Horizontal flow fields observed in Hinode G-band images II. Flow fields in the final stages of sunspot decay

    CERN Document Server

    Verma, M; Deng, N; Liu, C; Shimizu, T; Wang, H; Denker, C

    2011-01-01

    We present a subset of multi-wavelengths observations obtained with the Japanese Hinode mission, the Solar Dynamics Observatory (SDO), and the Vacuum Tower Telescope (VTT) at Observatorio del Teide, Tenerife, Spain during the time period from 2010 November 18-23. Horizontal proper motions were derived from G-band and Ca II H images, whereas line-of-sight velocities were extracted from VTT Echelle H-alpha 656.28 nm spectra and Fe I 630.25 nm spectral data of the Hinode/Spectro-Polarimeter, which also provided three-dimensional magnetic field information. The Helioseismic and Magnetic Imager on board SDO provided continuum images and line-of-sight magnetograms as context for the high-resolution observations for the entire disk passage of the active region. We have performed a quantitative study of photospheric and chromospheric flow fields in and around decaying sunspots. In one of the trailing sunspots of active region NOAA 11126, we observed moat flow and moving magnetic features (MMFs), even after its penumb...

  6. Nanoparticle separation with a miniaturized asymmetrical flow field-flow fractionation cartridge

    Directory of Open Access Journals (Sweden)

    David eMüller

    2015-07-01

    Full Text Available Asymmetrical Flow Field-Flow Fractionation (AF4 is a separation technique applicable to particles over a wide size range. Despite the many advantages of AF4, its adoption in routine particle analysis is somewhat limited by the large footprint of currently available separation cartridges, extended analysis times and significant solvent consumption. To address these issues, we describe the fabrication and characterization of miniaturized AF4 cartridges. Key features of the scale-down platform include simplified cartridge and reagent handling, reduced analysis costs and higher throughput capacities. The separation performance of the miniaturized cartridge is assessed using certified gold and silver nanoparticle standards. Analysis of gold nanoparticle populations indicates shorter analysis times and increased sensitivity compared to conventional AF4 separation schemes. Moreover, nanoparticulate titanium dioxide populations exhibiting broad size distributions are analyzed in a rapid and efficient manner. Finally, the repeatability and reproducibility of the miniaturized platform are investigated with respect to analysis time and separation efficiency.

  7. Nanoparticle separation with a miniaturized asymmetrical flow field-flow fractionation cartridge.

    Science.gov (United States)

    Müller, David; Cattaneo, Stefano; Meier, Florian; Welz, Roland; de Mello, Andrew J

    2015-01-01

    Asymmetrical Flow Field-Flow Fractionation (AF4) is a separation technique applicable to particles over a wide size range. Despite the many advantages of AF4, its adoption in routine particle analysis is somewhat limited by the large footprint of currently available separation cartridges, extended analysis times and significant solvent consumption. To address these issues, we describe the fabrication and characterization of miniaturized AF4 cartridges. Key features of the down-scaled platform include simplified cartridge and reagent handling, reduced analysis costs and higher throughput capacities. The separation performance of the miniaturized cartridge is assessed using certified gold and silver nanoparticle standards. Analysis of gold nanoparticle populations indicates shorter analysis times and increased sensitivity compared to conventional AF4 separation schemes. Moreover, nanoparticulate titanium dioxide populations exhibiting broad size distributions are analyzed in a rapid and efficient manner. Finally, the repeatability and reproducibility of the miniaturized platform are investigated with respect to analysis time and separation efficiency. PMID:26258119

  8. Factors affecting measurement of channel thickness in asymmetrical flow field-flow fractionation.

    Science.gov (United States)

    Dou, Haiyang; Jung, Euo Chang; Lee, Seungho

    2015-05-01

    Asymmetrical flow field-flow fractionation (AF4) has been considered to be a useful tool for simultaneous separation and characterization of polydisperse macromolecules or colloidal nanoparticles. AF4 analysis requires the knowledge of the channel thickness (w), which is usually measured by injecting a standard with known diffusion coefficient (D) or hydrodynamic diameter (dh). An accurate w determination is a challenge due to its uncertainties arising from the membrane's compressibility, which may vary with experimental condition. In the present study, influence of factors including the size and type of the standard on the measurement of w was systematically investigated. The results revealed that steric effect and the particles-membrane interaction by van der Waals or electrostatic force may result in an error in w measurement. PMID:25817708

  9. Hollow-Fiber Flow Field-Flow Fractionation for Mass Spectrometry: From Proteins to Whole Bacteria

    Science.gov (United States)

    Reschiglian, Pierluigi; Zattoni, Andrea; Rambaldi, Diana Cristina; Roda, Aldo; Hee Moon, Myeong

    Mass spectrometry (MS) provides analyte identification over a wide molar-mass range. However, particularly in the case of complex matrices, this ability is often enhanced by the use of pre-MS separation steps. A separation, prototype technique for the "gentle" fractionation of large/ultralarge analytes, from proteins to whole cells, is here described to reduce complexity and maintain native characteristics of the sample before MS analysis. It is based on flow field-flow fractionation, and it employs a micro-volume fractionation channel made of a ca. 20 cm hollow-fiber membrane of sub-millimeter section. The key advantages of this technique lie in the low volume and low-cost of the channel, which makes it suitable to a disposable usage. Fractionation performance and instrumental simplicity make it an interesting methodology for in-batch or on-line pre-MS treatment of such samples.

  10. Separation of platelets from other blood cells in continuous-flow by dielectrophoresis field-flow-fractionation

    OpenAIRE

    Piacentini, Niccolò; Mernier, Guillaume; Tornay, Raphaël; Renaud, Philippe

    2011-01-01

    We present a microfluidic device capable of separating platelets from other blood cells in continuous flow using dielectrophoresis field-flow-fractionation. The use of hydrodynamic focusing in combination with the application of a dielectrophoretic force allows the separation of platelets from red blood cells due to their size difference. The theoretical cell trajectory has been calculated by numerical simulations of the electrical field and flow speed, and is in agreement with the experiment...

  11. Influence of Hot Metal Flow State to the Hearth Flow Field during Blast Furnace Tapping

    OpenAIRE

    Hong-Wei Guo; Bing-Ji Yan; Jian-Liang Zhang; He-Lan Liang; Yi-Li Liu

    2013-01-01

    Blast furnace tapping is one of the most important aspects of BF iron-making, a process during which the ideal state is for the molten iron to remain the invariant and the level of liquid to remain stable. However, due to the viscosity of molten iron, the liquid level will tilt to one side near the tap-hole, causing the iron flow field during blast furnace tapping to change with time. This research simulated two cases of horizontal and inclined molten iron liquid levels in the process of blas...

  12. Characterization of Three-Stream Jet Flow Fields

    Science.gov (United States)

    Henderson, Brenda S.; Wernet, Mark P.

    2016-01-01

    Flow-field measurements were conducted on single-, dual- and three-stream jets using two-component and stereo Particle Image Velocimetry (PIV). The flow-field measurements complimented previous acoustic measurements. The exhaust system consisted of externally-plugged, externally-mixed, convergent nozzles. The study used bypass-to-core area ratios equal to 1.0 and 2.5 and tertiary-to-core area ratios equal to 0.6 and 1.0. Axisymmetric and offset tertiary nozzles were investigated for heated and unheated high-subsonic conditions. Centerline velocity decay rates for the single-, dual- and three-stream axisymmetric jets compared well when axial distance was normalized by an equivalent diameter based on the nozzle system total exit area. The tertiary stream had a greater impact on the mean axial velocity for the small bypass-to-core area ratio nozzles than for large bypass-to-core area ratio nozzles. Normalized turbulence intensities were similar for the single-, dual-, and three-stream unheated jets due to the small difference (10 percent) in the core and bypass velocities for the dual-stream jets and the low tertiary velocity (50 percent of the core stream) for the three-stream jets. For heated jet conditions where the bypass velocity was 65 percent of the core velocity, additional regions of high turbulence intensity occurred near the plug tip which were not present for the unheated jets. Offsetting the tertiary stream moved the peak turbulence intensity levels upstream relative to those for all axisymmetric jets investigated.

  13. Characterization of Three-Stream Jet Flow Fields

    Science.gov (United States)

    Henderson, Brenda S.; Wernet, Mark P.

    2016-01-01

    Flow-field measurements were conducted on single-, dual- and three-stream jets using two-component and stereo Particle Image Velocimetry (PIV). The flow-field measurements complimented previous acoustic measurements. The exhaust system consisted of externally-plugged, externally-mixed, convergent nozzles. The study used bypass-to-core area ratios equal to 1.0 and 2.5 and tertiary-to-core area ratios equal to 0.6 and 1.0. Axisymmetric and offset tertiary nozzles were investigated for heated and unheated high-subsonic conditions. Centerline velocity decay rates for the single-, dual- and three-stream axisymmetric jets compared well when axial distance was normalized by an equivalent diameter based on the nozzle system total exit area. The tertiary stream had a greater impact on the mean axial velocity for the small bypass-to-core area ratio nozzles than for large bypass-to-core area ratio nozzles. Normalized turbulence intensities were similar for the single-, dual-, and three-stream unheated jets due to the small difference (10%) in the core and bypass velocities for the dual-stream jets and the low tertiary velocity (50% of the core stream) for the three-stream jets. For heated jet conditions where the bypass velocity was 65% of the core velocity, additional regions of high turbulence intensity occurred near the plug tip which were not present for the unheated jets. Offsetting the tertiary stream moved the peak turbulence intensity levels upstream relative to those for all axisymmetric jets investigated.

  14. Numerical Simulation and Experimental Investigation of 3-D Separated Flow Field around a Blunt Body

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    @@Motivated by re-designing a fuselage in engineering application, the numerical and experimental investigation of the separated flow field around a special blunt body is described in this thesis. The aerodynamic response of the blunt body is successively studied. The thesis consists of four parts: the numerical simulation of the flow field around a two-dimensional blunt body; the numerical simulation of the flow field around a three-dimensional blunt body; the flow

  15. Biomat flow: fluorescent dye field experiments, pore-scale modeling of flow and transport properties, and field-scale flow models

    Science.gov (United States)

    Gerke, K.; Sidle, R. C.; Mallants, D.; Vasilyev, R.; Karsanina, M.; Skvortsova, E. B.; Korost, D. V.

    2013-12-01

    Recent studies highlight the important role that the upper litter layer in forest soils (biomat) plays in hillslope and catchment runoff generation. This biomat layer is a very loose material with high porosity and organic content. Direct sampling is usually problematic due to limited layer thickness. Conventional laboratory measurements can mobilize solids or even cause structure failure of the sample thus making measurements unreliable. It is also difficult to assess local variation in soil properties and transition zones using these methods; thus, they may not be applicable to biomat studies. However, if the physics of flow through this layer needs to be quantified and incorporated into a model, a detailed study of hydraulic properties is necessary. Herein we show the significance of biomat flow by staining experiments in the field, study its structure and transition to mineral soil layer using X-ray micro-tomography, assess hydraulic properties and structure differences using a pore-scale modeling approach, and, finally, use conventional variably-saturated flow modeling based on Richards equation to simulate flow in the hillslope. Using staining tracers we show that biomat flow in forested hillslopes can extend long distances (lateral displacement was about 1.2 times larger than for subsurface lateral flow) before infiltration occurs into deeper layers. The three-dimensional structure of an undisturbed sample (4 x 3 x 2.5 cm) of both biomat and deeper consolidated soil was obtained using an X-ray micro-tomography device with a resolution of 15 um. Local hydraulic properties (e.g., permeability and water retention curve) for numerous layers (e.g., transition zones, biomat, mineral soil) were calculated using Stokes flow FDM solution and pore-network modeling. Anisotropy, structure differences, and property fluctuations of different layers were quantified using local porosity analysis and correlation functions. Current results support the hypothesis that small

  16. Magnetic field flow phenomena in a falling particle receiver

    Science.gov (United States)

    Armijo, Kenneth M.; Ho, Clifford; Anderson, Ryan; Christian, Joshua; Babiniec, Sean; Ortega, Jesus

    2016-05-01

    Concentrating solar power (CSP) falling particle receivers are being pursued as a desired means for utilizing low-cost, high-absorptance particulate materials that can withstand high concentration ratios (˜1000 suns), operating temperatures above 700 °C, and inherent storage capabilities which can be used to reduce to levelized cost of electricity (LCOE)1. Although previous falling particle receiver designs have proven outlet temperatures above 800 °C, and thermal efficiencies between 80-90%, performance challenges still exist to operate at higher concentration ratios above 1000 suns and greater solar absorptance levels. To increase absorptance, these receivers will require enhanced particle residence time within a concentrated beam of sunlight. Direct absorption solid particle receivers that can enhance this residence time will have the potential to achieve heat-transfer media temperatures2 over 1000 °C. However, depending on particle size and external forces (e.g., external wind and flow due to convective heat losses), optimized particle flow can be severely affected, which can reduce receiver efficiency. To reduce particle flow destabilization and increase particle residence time on the receiver an imposed magnetic field is proposed based on a collimated design for two different methodologies. These include systems with ferromagnetic and charged particle materials. The approaches will be analytically evaluated based on magnetic field strength, geometry, and particle parameters, such as magnetic moment. A model is developed using the computational fluid dynamics (CFD) code ANSYS FLUENT to analyze these approaches for a ˜2 MWth falling particle receiver at Sandia National Laboratories5,6. Here, assessment will be made with respect to ferromagnetic particles such as iron-oxides, as well as charged particles. These materials will be parametrically assessed (e.g., type, size, dipole moment and geometry) over a range of magnetic permeability, μ values. Modeling

  17. Augmented Reality in Science Education

    DEFF Research Database (Denmark)

    Nielsen, Birgitte Lund; Brandt, Harald; Swensen, Hakon

    2015-01-01

    Augmented reality (AR) holds great promise as a learning tool. However, most extant studies in this field have focused on the technology itself. The poster presents findings from the first stage of the AR-sci project addressing the issue of applying AR for educational purposes. Benefits and...

  18. Size characterization and quantification of exosomes by asymmetrical-flow field-flow fractionation.

    Science.gov (United States)

    Sitar, Simona; Kejžar, Anja; Pahovnik, David; Kogej, Ksenija; Tušek-Žnidarič, Magda; Lenassi, Metka; Žagar, Ema

    2015-09-15

    In the past few years extracellular vesicles called exosomes have gained huge interest of scientific community since they show a great potential for human diagnostic and therapeutic applications. However, an ongoing challenge is accurate size characterization and quantification of exosomes because of the lack of reliable characterization techniques. In this work, the emphasis was focused on a method development to size-separate, characterize, and quantify small amounts of exosomes by asymmetrical-flow field-flow fractionation (AF4) technique coupled to a multidetection system (UV and MALS). Batch DLS (dynamic light-scattering) and NTA (nanoparticle tracking analysis) analyses of unfractionated exosomes were also conducted to evaluate their shape and internal structure, as well as their number density. The results show significant influence of cross-flow conditions and channel thickness on fractionation quality of exosomes, whereas the focusing time has less impact. The AF4/UV-MALS and DLS results display the presence of two particles subpopulations, that is, the larger exosomes and the smaller vesicle-like particles, which coeluted in AF4 together with impurities in early eluting peak. Compared to DLS and AF4-MALS results, NTA somewhat overestimates the size and the number density for larger exosome population, but it discriminates the smaller particle population. PMID:26291637

  19. Badak field's oil flowing; gas is ready

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, J.L.

    1975-03-24

    Within about 5 y after discovery of the Badak field in East Kalimantan, Indonesia, first deliveries are scheduled to be made from a new LNG plant fed over 530 million CF/day by the field. Badak is also flowing about 13,000 bbl/day of oil, which is piped to the Santan terminal. Other promising gas reserves found in the area could boost production to a level that - when coupled with Badak - would support an LNG-plant input of up to 1 billion CF/day. Indeed, the plant is being built with provisions for adding 2 more trains later. The plant will use an Air Products Co. propane-precooled liquefaction process. The storage system will include four 600,000-bbl aboveground double-wall insulated tanks. Seven 4.4 million cu ft (125,000 cu m) tankers will be constructed to move the LNG from Bontang Bay to market in Japan, where 4 receiving terminals will be built - Chubu, Himeji, Kitakyushu, and Semboku II.

  20. NUMERICAL ANALYSIS ON THREEDIMENSIONAL FLOW FIELD OF TURBINE IN TORQUE CONVERTER

    Institute of Scientific and Technical Information of China (English)

    LIU Yue; PAN Yuxue; LIU Chunbao

    2007-01-01

    Three-dimensional flow field of turbine in torque converter is simulated by numerical calculation in order to improve the performance of torque converter. Calculation model of a torque converter is presented based on the mixing-plane technology. In the calculation of flow field, the 3D N-S equations are separated by finite-volume method and solved by semi-implicit method for pressure-linked equations(SIMPLE). Based on flow field calculation, the flow field of turbine is simulated. The velocity and pressure in the flow field of turbine are analyzed. The external performance of the torque converter is also calculated. Results of flow simulation show that there are secondary flow, off flow and velocity gradient in turbine passage. The validity of numerical simulation is verified by comparing the results of numerical simulation with experiment data.

  1. Intermittent magnetic field excitation by a turbulent flow of liquid sodium

    OpenAIRE

    Nornberg, M. D.; Spence, E. J.; Kendrick, R. D.; Jacobson, C. M.; Forest, C. B.

    2006-01-01

    The magnetic field measured in the Madison Dynamo Experiment shows intermittent periods of growth when an axial magnetic field is applied. The geometry of the intermittent field is consistent with the fastest growing magnetic eigenmode predicted by kinematic dynamo theory using a laminar model of the mean flow. Though the eigenmodes of the mean flow are decaying, it is postulated that turbulent fluctuations of the velocity field change the flow geometry such that the eigenmode growth rate is ...

  2. Magnetic Field Generation and Zonal Flows in the Gas Giants

    Science.gov (United States)

    Duarte, L.; Wicht, J.; Gastine, T.

    2013-12-01

    The surface dynamics of Jupiter and Saturn is dominated by a banded system of fierce zonal winds. The depth of these winds remains unclear but they are thought to be confined to the very outer envelopes where hydrogen remains molecular and the electrical conductivity is negligible. The dynamo responsible for the dipole dominated magnetic fields of both Gas Giants, on the other hand, likely operates in the deeper interior where hydrogen assumes a metallic state. We present numerical simulations that attempt to model both the zonal winds and the interior dynamo action in an integrated approach. Using the anelastic version of the MHD code MagIC, we explore the effects of density stratification and radial electrical conductivity variations. The electrical conductivity is assumed to remain constant in the thicker inner metallic region and decays exponentially towards the outer boundary throughout the molecular envelope. Our results show that the combination of stronger density stratification (Δρ≈55) and a weaker conducting outer layer is essential for reconciling dipole dominated dynamo action and a fierce equatorial zonal jet. Previous simulations with homogeneous electrical conductivity show that both are mutually exclusive, with solutions either having strong zonal winds and multipolar magnetic fields or weak zonal winds and dipole dominated magnetic fields. The particular setup explored here allows the equatorial jet to remain confined to the weaker conducting region where is does not interfere with the deeper seated dynamo action. The equatorial jet can afford to remain geostrophic and reaches throughout the whole shell. This is not an option for the additional mid to higher latitude jets, however. In dipole dominated dynamo solutions, appropriate for the Gas Giants, zonal flows remain very faint in the deeper dynamo region but increase in amplitude in the weakly conducting outer layer in some of our simulations. This suggests that the mid to high latitude jets

  3. Optimization and evaluation of asymmetric flow field-flow fractionation of silver nanoparticles.

    Science.gov (United States)

    Loeschner, Katrin; Navratilova, Jana; Legros, Samuel; Wagner, Stephan; Grombe, Ringo; Snell, James; von der Kammer, Frank; Larsen, Erik H

    2013-01-11

    Asymmetric flow field-flow fractionation (AF(4)) in combination with on-line optical detection and mass spectrometry is one of the most promising methods for separation and quantification of nanoparticles (NPs) in complex matrices including food. However, to obtain meaningful results regarding especially the NP size distribution a number of parameters influencing the separation need to be optimized. This paper describes the development of a separation method for polyvinylpyrrolidone-stabilized silver nanoparticles (AgNPs) in aqueous suspension. Carrier liquid composition, membrane material, cross flow rate and spacer height were shown to have a significant influence on the recoveries and retention times of the nanoparticles. Focus time and focus flow rate were optimized with regard to minimum elution of AgNPs in the void volume. The developed method was successfully tested for injected masses of AgNPs from 0.2 to 5.0 μg. The on-line combination of AF(4) with detection methods including ICP-MS, light absorbance and light scattering was helpful because each detector provided different types of information about the eluting NP fraction. Differences in the time-resolved appearance of the signals obtained by the three detection methods were explained based on the physical origin of the signal. Two different approaches for conversion of retention times of AgNPs to their corresponding sizes and size distributions were tested and compared, namely size calibration with polystyrene nanoparticles (PSNPs) and calculations of size based on AF(4) theory. Fraction collection followed by transmission electron microscopy was performed to confirm the obtained size distributions and to obtain further information regarding the AgNP shape. Characteristics of the absorbance spectra were used to confirm the presence of non-spherical AgNP. PMID:23261297

  4. A full-field and real-time 3D surface imaging augmented DOT system for in-vivo small animal studies

    Science.gov (United States)

    Yi, Steven X.; Yang, Bingcheng; Yin, Gongjie

    2010-02-01

    A crucial parameter in Diffuse Optical Tomography (DOT) is the construction of an accurate forward model, which greatly depends on tissue boundary. Since photon propagation is a three-dimensional volumetric problem, extraction and subsequent modeling of three-dimensional boundaries is essential. Original experimental demonstration of the feasibility of DOT to reconstruct absorbers, scatterers and fluorochromes used phantoms or tissues confined appropriately to conform to easily modeled geometries such as a slab or a cylinder. In later years several methods have been developed to model photon propagation through diffuse media with complex boundaries using numerical solutions of the diffusion or transport equation (finite elements or differences) or more recently analytical methods based on the tangent-plane method . While optical examinations performed simultaneously with anatomical imaging modalities such as MRI provide well-defined boundaries, very limited progress has been done so far in extracting full-field (360 degree) boundaries for in-vivo three-dimensional DOT stand-alone imaging. In this paper, we present a desktop multi-spectrum in-vivo 3D DOT system for small animal imaging. This system is augmented with Technest's full-field 3D cameras. The built system has the capability of acquiring 3D object surface profiles in real time and registering 3D boundary with diffuse tomography. Extensive experiments are performed on phantoms and small animals by our collaborators at the Center for Molecular Imaging Research (CMIR) at Massachusetts General Hospital (MGH) and Harvard Medical School. Data has shown successful reconstructed DOT data with improved accuracy.

  5. AUGMENTATION-RELATED BRAIN PLASTICITY

    Directory of Open Access Journals (Sweden)

    Giovanni eDi Pino

    2014-06-01

    Full Text Available Today, the anthropomorphism of the tools and the development of neural interfaces require reconsidering the concept of human-tools interaction in the framework of human augmentation. This review analyzes the plastic process that the brain undergoes when it comes into contact with augmenting artificial sensors and effectors and, on the other hand, the changes that the use of external augmenting devices produces in the brain.Hitherto, few studies investigated the neural correlates of augmentation, but clues on it can be borrowed from logically-related paradigms: sensorimotor training, cognitive enhancement, cross-modal plasticity, sensorimotor functional substitution, use and embodiment of tools.Augmentation modifies function and structure of a number of areas, i.e. primary sensory cortices shape their receptive fields to become sensitive to novel inputs. Motor areas adapt the neuroprosthesis representation firing-rate to refine kinematics. As for normal motor outputs, the learning process recruits motor and premotor cortices and the acquisition of proficiency decreases attentional recruitment, focuses the activity on sensorimotor areas and increases the basal ganglia drive on the cortex. Augmentation deeply relies on the frontoparietal network. In particular, premotor cortex is involved in learning the control of an external effector and owns the tool motor representation, while the intraparietal sulcus extracts its visual features. In these areas, multisensory integration neurons enlarge their receptive fields to embody supernumerary limbs. For operating an anthropomorphic neuroprosthesis, the mirror system is required to understand the meaning of the action, the cerebellum for the formation of its internal model and the insula for its interoception. In conclusion, anthropomorphic sensorized devices can provide the critical sensory afferences to evolve the exploitation of tools through their embodiment, reshaping the body representation and the

  6. Augmentation-related brain plasticity

    Science.gov (United States)

    Di Pino, Giovanni; Maravita, Angelo; Zollo, Loredana; Guglielmelli, Eugenio; Di Lazzaro, Vincenzo

    2014-01-01

    Today, the anthropomorphism of the tools and the development of neural interfaces require reconsidering the concept of human-tools interaction in the framework of human augmentation. This review analyses the plastic process that the brain undergoes when it comes into contact with augmenting artificial sensors and effectors and, on the other hand, the changes that the use of external augmenting devices produces in the brain. Hitherto, few studies investigated the neural correlates of augmentation, but clues on it can be borrowed from logically-related paradigms: sensorimotor training, cognitive enhancement, cross-modal plasticity, sensorimotor functional substitution, use and embodiment of tools. Augmentation modifies function and structure of a number of areas, i.e., primary sensory cortices shape their receptive fields to become sensitive to novel inputs. Motor areas adapt the neuroprosthesis representation firing-rate to refine kinematics. As for normal motor outputs, the learning process recruits motor and premotor cortices and the acquisition of proficiency decreases attentional recruitment, focuses the activity on sensorimotor areas and increases the basal ganglia drive on the cortex. Augmentation deeply relies on the frontoparietal network. In particular, premotor cortex is involved in learning the control of an external effector and owns the tool motor representation, while the intraparietal sulcus extracts its visual features. In these areas, multisensory integration neurons enlarge their receptive fields to embody supernumerary limbs. For operating an anthropomorphic neuroprosthesis, the mirror system is required to understand the meaning of the action, the cerebellum for the formation of its internal model and the insula for its interoception. In conclusion, anthropomorphic sensorized devices can provide the critical sensory afferences to evolve the exploitation of tools through their embodiment, reshaping the body representation and the sense of the self

  7. Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation.

    Science.gov (United States)

    Williams, P Stephen

    2015-06-01

    In asymmetrical flow field-flow fractionation (As-FlFFF), only the membrane-covered accumulation wall is permeable to fluid; the opposite channel wall is impermeable. Fluid enters the channel at the inlet and exits partly through the membrane-covered accumulation wall and partly through the channel outlet. This means that not only does the volumetric channel flow rate decrease along the channel length as fluid exits through the membrane but also the cross-channel component to fluid velocity must approach zero at the impermeable wall. This dependence of cross-channel fluid velocity on distance across the channel thickness influences the equilibrium concentration profile for the sample components introduced to the channel. The concentration profile departs from the exponential profile predicted for the ideal model of field-flow fractionation. This influences both the retention ratio and the principal contribution to bandspreading--the nonequilibrium contribution. The derivation of an equation for the nonequilibrium bandspreading parameter χ in As-FlFFF is presented, and its numerical solution graphed. At high retention, it is shown that the solutions for both retention ratio R and χ converge on those for the ideal model, as expected. At lower levels of retention, the departures from the ideal model are significant, particularly for bandspreading. For example, at a level of retention corresponding to a retention parameter λ of 0.05, R is almost 4% higher than for the ideal model (0.28047 as compared to 0.27000) but the value of χ is almost 60% higher. The equations presented for both R and χ include a first-order correction for the finite size of the particles--the steric exclusion correction. These corrections are shown to be significant for particle sizes eluting well before steric inversion. For example, particles of half the inversion diameter are predicted to elute 25% slower and to show almost 40% higher bandspreading when steric effects are not accounted

  8. On The Temperature Field of a Viscous Reacting Flow Near a Moving Wall with Thermal Radiation

    OpenAIRE

    B.I. Olajuwon; Ayeni, R. O.

    2005-01-01

    We examine the temperature field of a viscous reacting flow near a moving wall with thermal radiation. Of particular interest is the effect of thermal radiation parameter and the Frank-kamenetskii parameter on the flow.

  9. Flow field topology of submerged jets with fractal generated turbulence

    Science.gov (United States)

    Cafiero, Gioacchino; Discetti, Stefano; Astarita, Tommaso

    2015-11-01

    Fractal grids (FGs) have been recently an object of numerous investigations due to the interesting capability of generating turbulence at multiple scales, thus paving the way to tune mixing and scalar transport. The flow field topology of a turbulent air jet equipped with a square FG is investigated by means of planar and volumetric particle image velocimetry. The comparison with the well-known features of a round jet without turbulence generators is also presented. The Reynolds number based on the nozzle exit section diameter for all the experiments is set to about 15 000. It is demonstrated that the presence of the grid enhances the entrainment rate and, as a consequence, the scalar transfer of the jet. Moreover, due to the effect of the jet external shear layer on the wake shed by the grid bars, the turbulence production region past the grid is significantly shortened with respect to the documented behavior of fractal grids in free-shear conditions. The organization of the large coherent structures in the FG case is also analyzed and discussed. Differently from the well-known generation of toroidal vortices due to the growth of azimuthal disturbances within the jet shear layer, the fractal grid introduces cross-wise disturbs which produce streamwise vortices; these structures, although characterized by a lower energy content, have a deeper streamwise penetration than the ring vortices, thus enhancing the entrainment process.

  10. Cfd Simulation to the Flow Field of Venturi Injector

    Science.gov (United States)

    Huang, Xingfa; Li, Guangyong; Wang, Miao

    Venturi injector is widely used in fertigation system due to its obvious advantages such as cheap and robust system without mobile pieces, simple structure, convenient to operation, stable performance, needless of external energy for operation etc. At present, the hydraulic parameters such as suction capacity (injection rate) for the most of the Venturi injectors produced domestically are not very desirable. In this paper, CFD (Computational Fluid Dynamics) method was used to simulate the inner flow field of the Venturi injectors, and the relationships among the structure parameters (i.e., throat length L, throat diameter D, slot diameter Da) and suction capacity q, and the optimal structure sizes of the Venturi injector were analyzed. The results show that when the inlet pressure and the slot position are kept unchanged as the sample one, the suction capacity of Venturi injector increases with the decrease of throat diameter D and throat length L, and the increase of slot diameter Da; while keeping the slot diameter Da, throat diameter D and throat length L unchanged, the suction capacity of Venturi injector q increases with the increase of inlet pressure P. The optimal combination of the structural parameters in this size was selected as follows: throat diameter D=8mm, slot diameter Da=18.5mm, and throat length L=14mm. In this case, the suction capacity of the Venturi injector q=1.203m3/h. The results can provide theoretic support for domestic Venturi injector research, design and manufacturing.

  11. Characteristics of gas explosion flow fields in complex pipelines

    Institute of Scientific and Technical Information of China (English)

    Zhu Zhao; Jia Zhenyuan; Luo Haizhu

    2015-01-01

    The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that, both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000 K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found. The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security require-ments fully.

  12. Quantum dot agglomerates in biological media and their characterization by asymmetrical flow field-flow fractionation.

    Science.gov (United States)

    Moquin, Alexandre; Neibert, Kevin D; Maysinger, Dusica; Winnik, Françoise M

    2015-01-01

    The molecular composition of the biological environment of nanoparticles influences their physical properties and changes their pristine physicochemical identity. In order to understand, or predict, the interactions of cells with specific nanoparticles, it is critical to know their size, shape, and agglomeration state not only in their nascent state but also in biological media. Here, we use asymmetrical flow field-flow fractionation (AF4) with on-line multiangle light scattering (MALS), dynamic light scattering (DLS) and UV-Visible absorption detections to determine the relative concentration of isolated nanoparticles and agglomerates in the case of three types of semi-conductor quantum dots (QDs) dispersed in Dulbecco's Modified Eagle Media (DMEM) containing 10% of fetal bovine serum (DMEM-FBS). AF4 analysis also yielded the size and size distribution of the agglomerates as a function of the time of QDs incubation in DMEM-FBS. The preferred modes of internalization of the QDs are assessed for three cell-types, N9 microglia, human hepatocellular carcinoma cells (HepG2) and human embryonic kidney cells (Hek293), by confocal fluorescence imaging of live cells, quantitative determination of the intracellular QD concentration, and flow cytometry. There is an excellent correlation between the agglomeration status of the three types of QDs in DMEM-FBS determined by AF4 analysis and their preferred mode of uptake by the three cell lines, which suggests that AF4 yields an accurate description of the nanoparticles as they encounter cells and advocates its use as a means to characterize particles under evaluation. PMID:25542679

  13. Influence of Hot Metal Flow State to the Hearth Flow Field during Blast Furnace Tapping

    Directory of Open Access Journals (Sweden)

    Hong-Wei Guo

    2013-08-01

    Full Text Available Blast furnace tapping is one of the most important aspects of BF iron-making, a process during which the ideal state is for the molten iron to remain the invariant and the level of liquid to remain stable. However, due to the viscosity of molten iron, the liquid level will tilt to one side near the tap-hole, causing the iron flow field during blast furnace tapping to change with time. This research simulated two cases of horizontal and inclined molten iron liquid levels in the process of blast furnace tapping. This study also discusses different hearth erosion situations and explains the rationality of blast furnace large-scale trends from the perspective of molten iron liquid level stability.

  14. Augmented reality system

    Science.gov (United States)

    Lin, Chien-Liang; Su, Yu-Zheng; Hung, Min-Wei; Huang, Kuo-Cheng

    2010-08-01

    In recent years, Augmented Reality (AR)[1][2][3] is very popular in universities and research organizations. The AR technology has been widely used in Virtual Reality (VR) fields, such as sophisticated weapons, flight vehicle development, data model visualization, virtual training, entertainment and arts. AR has characteristics to enhance the display output as a real environment with specific user interactive functions or specific object recognitions. It can be use in medical treatment, anatomy training, precision instrument casting, warplane guidance, engineering and distance robot control. AR has a lot of vantages than VR. This system developed combines sensors, software and imaging algorithms to make users feel real, actual and existing. Imaging algorithms include gray level method, image binarization method, and white balance method in order to make accurate image recognition and overcome the effects of light.

  15. Magnetohydrodynamic Augmented Propulsion Experiment

    Science.gov (United States)

    Litchford, Ron J.

    2008-01-01

    Over the past several years, efforts have been under way to design and develop an operationally flexible research facility for investigating the use of cross-field MHD accelerators as a potential thrust augmentation device for thermal propulsion systems. The baseline configuration for this high-power experimental facility utilizes a 1.5-MWe multi-gas arc-heater as a thermal driver for a 2-MWe MHD accelerator, which resides in a large-bore 2-tesla electromagnet. A preliminary design study using NaK seeded nitrogen as the working fluid led to an externally diagonalized segmented MHD channel configuration based on an expendable heat-sink design concept. The current status report includes a review of engineering/design work and performance optimization analyses and summarizes component hardware fabrication and development efforts, preliminary testing results, and recent progress toward full-up assembly and testing

  16. EFFECT OF THE FLOW FIELD DEFORMATION IN THE WIND TUNNEL ON THE AERODYNAMIC COEFFICIENTS

    Directory of Open Access Journals (Sweden)

    Dušan Maturkanič

    2015-06-01

    Full Text Available The flow field quality has a principal signification at wind tunnel measurement. The creation of the flow field of air by fan leads to the rotation of entire flow field which is, moreover, deformed at the bends of the wind tunnel with close circulation. Despite the wind tunnels are equipped with the devices which eliminate these non-uniformities, in the most of cases, the air flow field has not ideal parameters in the test section. For the evaluation of the measured results of the model in the wind tunnel, the character of flow field deformation is necessary. The following text describes the possible general forms of the flow field nonuniformity and their effect on the aerodynamic coefficients calculation.

  17. Effects of local flow field on flow accelerated corrosion. Wall thinning rate at elbow pipe

    International Nuclear Information System (INIS)

    In order to evaluate the effects of a flow field on wall thinning rate due to flow accelerated corrosion (FAC), the authors have carried out wall thinning rate measurements using the electrical resistance method, measurements of the velocity profile, and numerical simulation for each piping component such as an orifice and a globe valve. In this study, wall thinning rates were measured were conducted at an elbow pipe without the orifice. In the wall thinning rate measurement, a test loop operated at high temperature and high pressure conditions was used. The pipe inner diameter was 50mm, and the average velocity was changed during the experiment from 6.22m/s to 4.98m/s. The water temperature was controlled within 150±1degC. The wall thinning rates in the elbow pipe were larger than those upstream and downstream from the elbow pipe. The distribution of wall thinning rates in the elbow pipe was asymmetrical to the center axis in the circumferential direction of the pipe, and the wall thinning rate at the extrados of the elbow pipe was larger than that at intrados. (author)

  18. Asymmetrical flow field-flow fractionation for the analysis of PEG-asparaginase.

    Science.gov (United States)

    John, C; Herz, T; Boos, J; Langer, K; Hempel, G

    2016-01-01

    Monomethoxypolyethylene glycol L-asparaginase (PEG-ASNASE) is the PEGylated version of the enzyme L-asparaginase (ASNASE). Both are used for remission induction in acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). The treatment control is generally carried out by performing activity assays, though methods to determine the actual enzyme rather than its activity are rare. Using asymmetrical flow field-flow fractionation (AF4) offered the chance to develop a method capable of simultaneously measuring PEG-ASNASE and PEG. A method validation was performed in accordance with FDA guidelines for PEG-ASNASE from non-biological solutions. The method unfolded a linearity of 15-750 U/mL with coefficients of correlation of r(2)>0.99. The coefficients of variation (CV) for within-run and between-run variability were 1.18-10.15% and 2.43-8.73%, respectively. Furthermore, the method was used to perform stability tests of the product Oncaspar® (PEG-ASNASE) and estimation of the molecular weight by multi-angle light scattering (MALS) of stressed samples to correlate them with the corresponding activity. The findings indicate that Oncaspar® stock solution should not be stored any longer than 24 h at room temperature and cannot be frozen in pure aqueous media. The validated method might be useful for the pharmaceutical industry and its quality control of PEG-ASNASE production. PMID:26695272

  19. High Speed Size Sorting of Subcellular Organelles by Flow Field-Flow Fractionation.

    Science.gov (United States)

    Yang, Joon Seon; Lee, Ju Yong; Moon, Myeong Hee

    2015-06-16

    Separation/isolation of subcellular species, such as mitochondria, lysosomes, peroxisomes, Golgi apparatus, and others, from cells is important for gaining an understanding of the cellular functions performed by specific organelles. This study introduces a high speed, semipreparative scale, biocompatible size sorting method for the isolation of subcellular organelle species from homogenate mixtures of HEK 293T cells using flow field-flow fractionation (FlFFF). Separation of organelles was achieved using asymmetrical FlFFF (AF4) channel system at the steric/hyperlayer mode in which nuclei, lysosomes, mitochondria, and peroxisomes were separated in a decreasing order of hydrodynamic diameter without complicated preprocessing steps. Fractions in which organelles were not clearly separated were reinjected to AF4 for a finer separation using the normal mode, in which smaller sized species can be well fractionated by an increasing order of diameter. The subcellular species contained in collected AF4 fractions were examined with scanning electron microscopy to evaluate their size and morphology, Western blot analysis using organelle specific markers was used for organelle confirmation, and proteomic analysis was performed with nanoflow liquid chromatography-tandem mass spectrometry (nLC-ESI-MS/MS). Since FlFFF operates with biocompatible buffer solutions, it offers great flexibility in handling subcellular components without relying on a high concentration sucrose solution for centrifugation or affinity- or fluorescence tag-based sorting methods. Consequently, the current study provides an alternative, competitive method for the isolation/purification of subcellular organelle species in their intact states. PMID:26005782

  20. Rational strategy for characterization of nanoscale particles by asymmetric-flow field flow fractionation: a tutorial.

    Science.gov (United States)

    Gigault, Julien; Pettibone, John M; Schmitt, Charlène; Hackley, Vincent A

    2014-01-27

    This tutorial proposes a comprehensive and rational measurement strategy that provides specific guidance for the application of asymmetric-flow field flow fractionation (A4F) to the size-dependent separation and characterization of nanoscale particles (NPs) dispersed in aqueous media. A range of fractionation conditions are considered, and challenging applications, including industrially relevant materials (e.g., metal NPs, asymmetric NPs), are utilized in order to validate and illustrate this approach. We demonstrate that optimization is material dependent and that polystyrene NPs, widely used as a reference standard for retention calibration in A4F, in fact represent a class of materials with unique selectivity, recovery and optimal conditions for fractionation; thus use of these standards to calibrate retention for other materials must be validated a posteriori. We discuss the use and relevance of different detection modalities that can potentially yield multi-dimensional and complementary information on NP systems. We illustrate the fractionation of atomically precise nanoclusters, which are the lower limit of the nanoscale regime. Conversely, we address the upper size limit for normal mode elution in A4F. The protocol for A4F fractionation, including the methods described in the present work is proposed as a standardized strategy to realize interlaboratory comparability and to facilitate the selection and validation of material-specific measurement parameters and conditions. It is intended for both novice and advanced users of this measurement technology. PMID:24418128

  1. Depolymerization study of sodium hyaluronate by flow field-flow fractionation/multiangle light scattering.

    Science.gov (United States)

    Kwon, Ji Hye; Hwang, Euijin; Cho, Il-Hwan; Moon, Myeong Hee

    2009-09-01

    Thermal depolymerization of ultrahigh-molecular-weight (UHMW) sodium hyaluronate (NaHA) was studied systematically by using frit-inlet asymmetrical flow field-flow fractionation/multiangle light scattering/differential refractive index (FI-AFlFFF/MALS/DRI). FI-AFlFFF was utilized for the size separation of NaHA samples which had been thermally degraded for varied treatment times, followed by light-scattering detection to determine MW and structural information of degraded NaHA products. Analysis of NaHA products showed time-dependent depolymerization of raw molecules into smaller-MW components, as well as unfolding of compact structures of UHMW NaHA. To determine whether the observed decrease in MW of sodium hyaluronate originated from the chain degradation of UHMW molecules or from dissociation of entangled complex particles that may have been formed by intermolecular association, narrow size fractions (1 x 10(7)-6 x 10(7) and >6 x 10(7) MW) of NaHA molecules were collected during FlFFF separation and followed by thermal treatment. Subsequent FI-AFlFFF/MALS analysis of collected fractions after thermal treatment suggested that the ultrahigh-MW region (>10(7) Da) of NaHA is likely to result from supermolecular structures formed by aggregation of large molecules. PMID:19649622

  2. The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

    KAUST Repository

    Elbaz, Ayman M.

    2015-08-29

    The stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work. The stability map of partial premixed flames illustrates that the flames are stable between two extinction limits. A low extinction limit when partial premixed flames approach non-premixed flame conditions, and a high extinction limit, with the partial premixed flames approach fully premixed flame conditions. These two limits showed that the most stable flame conditions are achieved at a certain degree of partial premixed. The stability is improved by adding air co-flow. As the air co-flow velocity increases the most stable flames are those that approach fully premixed. The turbulent flow field of three flames at 0, 5, 10 m/s co-flow velocity are investigated using Stereo Particle Image Velocimetry (SPIV) in order to explore the improvement of the flame stability due to the use of air co-flow. The three flames are all at a jet equivalence ratio (Φj) of 2, fixed level of partial premixing and jet Reynolds number (Rej) of 10,000. The use of co-flow results in the formation of two vortices at the cone exit. These vortices act like stabilization anchors for the flames to the nozzle tip. With these vortices in the flow field, the reaction zone shifts toward the reduced turbulence intensity at the nozzle rim of the cone. Interesting information about the structure of the flow field with and without co-flow are identified and reported in this work.

  3. Effect of electromagnetic swirling flow in slide-gate SEN on flow field in square billet continuous casting mold

    Institute of Scientific and Technical Information of China (English)

    Dianqiao GENG; Hong LEI; Jicheng HE; Haitao LIU

    2012-01-01

    In order to weaken the bias flow in the submerged entry nozzle (SEN) with slidegate,the rotating magnetic field was imposed.The numerical method was employed to investigate the effect of rotating magnetic field on the flow field in the SEN and the mold under different slide-gate opening ratios.Numerical results showed that when the slide-gate opening ratio is smaller than 100%,the flow field in the SEN and the mold become asymmetry and there is an obvious circulation under the slidegate in the SEN.With increasing exciting current,the divergent angle of liquid steel at the SEN outlet increases,the impact depth of liquid steel in the mold decreases.With increasing slide-gate opening ratio,the impact depth of liquid steel in the mold increases and the required exciting current to weaken the bias flow should increase.

  4. Numerical simulation of seepage flow field in groundwater source heat pump system and its influence on temperature field

    Institute of Scientific and Technical Information of China (English)

    Jihua HU; Yanjun ZHANG; Danyan DU; Gang WU; Ziwang YU; Chen WANG; Fuquan NI

    2008-01-01

    Energy utilization in the aquifers is a new technology closely related to development of heat pump technique. It is significant for the flow distribution to be predicted in the aquifer surrounding the Groundwater Source Heat Pump System (GSHPS). The authors presented a new concept of "flow transfixion" by analyzing general features of aquifers, and then discussed interaction of the flow transfixion with the heat transfixion, which has practical significance to projects. A numerical model of groundwater flow was established based on the basic tenets of water-heat transferring in the aquifer. On this basis the flow field and the temperature field of GSHPS for a site in Shenyang City were numerically simulated. The basis of the flow transfixion was obtained; it was discussed for the influence of the flow transfixion on the heat transfixion. To a certain extent, the study offers some reference for the projects' design of GSHP in the studied area.

  5. Asymmetrical flow field-flow fractionation with on-line detection for drug transfer studies: a feasibility study

    DEFF Research Database (Denmark)

    Hinna, A.; Steiniger, F.; Hupfeld, S.; Brandl, M.; Kuntsche, J.

    2014-01-01

    Knowledge about drug retention within colloidal carriers is of uppermost importance particularly if drug targeting is anticipated. The aim of the present study was to evaluate asymmetrical flow field-flow fractionation (AF4) with on-line UV/VIS drug quantification for its suitability to determine...

  6. The study of slip line field and upper bound method based on associated flow and non-associated flow rules

    Institute of Scientific and Technical Information of China (English)

    Zheng Yingren; Deng Chujian; Wang Jinglin

    2010-01-01

    At present,associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials.So the stress characteristic line conforms to the velocity line.It is proved that geotechnical materials do not abide by the associated flow rule.It is impossible for the stress characteristic line to conform to the velocity line.Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle,so that the velocity line must be studied by non-associated flow rule.According to limit analysis theory,the theory of slip line field is put forward in this paper,and then the ultimate boating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow rule individually.These two results are identical since the ultimate bearing capacity is independent of flow rule.On the contrary,the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associated flow rule is incorrect.

  7. Flow and Stress Field Analysis of Different Fluids and Blades for Fermentation Process

    OpenAIRE

    Cheng-Chi Wang; Po-Jen Cheng; Kuo-Chi Liu; Ming-Yi Tsai

    2014-01-01

    Fermentation techniques are applied for the biotechnology and are widely used for food manufacturing, materials processing, chemical reaction, and so forth. Different fluids and types of blades in the tank for fermentation cause distinct flow and stress field distributions on the surface between fluid and blade and various flow reactions in the tank appear. This paper is mainly focused on the analysis of flow field with different fluid viscosities and also studied the stress field acting on t...

  8. Far field pressure fluctuations and coherent structures in a low mach number turbulent jet flow

    OpenAIRE

    Camussi, Roberto; Felli, Mario

    2005-01-01

    Simultaneous far field pressur/in-flow velocity fluctuations are measured in a turbulent jet flow at low Ma number. The experiment is conducted in an acustically controlled enviroment using LDV and standard microphones. Velocity signals acquired in several positions within the flow field are conditioned on the far field pressure peaks and signatures of ensamble averaged noise emitting event are retrieved. Present results confirms previous findings obtained on the same apparatus showing that i...

  9. Nonlinear generation of sheared flows and zonal magnetic fields by electron whistlers in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064 (India); Shukla, Padma K., E-mail: profshukla@yahoo.de [Institute for Theoretical Physics, International Centre for Advanced Studies in Physical Sciences, Ruhr University Bochum, D-44780 Bochum (Germany)

    2011-10-24

    The nonlinear generation of shear field and flow in whistler waves is considered. It is shown that a coherent parametric process leads to modulational instability of four waves whistler interaction. Growth rates for the flow/field are compared with published simulation results. -- Highlights: → The mechanisms of self-generated flow and field has been done in EMHD plasma. → A parametric process leads to modulational instability. → The growth rate matches with simulation results.

  10. Research on the flow field of undershot cross-flow water turbines using experiments and numerical analysis

    International Nuclear Information System (INIS)

    The purpose of this research is to develop a water turbine appropriate for low-head open channels in order to effectively utilize the unused hydropower energy of rivers and agricultural waterways. The application of the cross-flow runner to open channels as an undershot water turbine has come under consideration and, to this end, a significant simplification was attained by removing the casings. However, the flow field of undershot cross-flow water turbines possesses free surfaces. This means that with the variation in the rotational speed, the water depth around the runner will change and flow field itself is significantly altered. Thus it is necessary to clearly understand the flow fields with free surfaces in order to improve the performance of this turbine. In this research, the performance of this turbine and the flow field were studied through experiments and numerical analysis. The experimental results on the performance of this turbine and the flow field were consistent with the numerical analysis. In addition, the inlet and outlet regions at the first and second stages of this water turbine were clarified

  11. Analysis on the design and property of flow field plates of innovative direct methanol fuel cell.

    Science.gov (United States)

    Chang, Ho; Kao, Mu-Jung; Chen, Chih-Hao; Kuo, Chin-Guo; Lee, Kuang-Ying

    2014-10-01

    The paper uses technology of lithography process to etch flow fields on single side of a printed circuit board (PCB), and combines flow field plate with collector plate to make innovative anode flow field plates and cathode flow field plates required in direct methanol fuel cell (DMFC), and meanwhile makes membrane electrode assembly (MEA) and methanol fuel plate. The flow field plates are designed to be in the form of serpentine flow field. The paper measured the assembled DMFC to achieve the overall efficiency of DMFC under the conditions of different screw torques and different concentration, flow rate and temperature of methanol. Experimental results show that when the flow field width of flow field plate is 1 mm, the screw torque is 16 kgf/cm, and the concentration, flow rate and temperature of methanol-water are 1 M, 180 ml/h and 50 degrees C respectively, the prepared DMFC can have better power density of 5.5 mW/cm2, 5.4 mW/cm2, 11.2 mW/cm2 and 11.8 mW/cm2. Besides, the volume of the DMFC designed and assembled by the study is smaller than the generally existing DMFC by 40%. PMID:25942924

  12. A Survey on Augmented Reality Challenges and Tracking

    OpenAIRE

    Ihsan Rabbi; Sehat Ullah

    2013-01-01

    This survey paper presents classification of different challenges and tracking techniques in the field of Augmented Reality. The challenges in augmented reality are categorized in performance challenges, alignment challenges, interaction challenges, mobility/portability challenges and visualization challenges. Augmented reality tracking techniques are mainly divided into sensor based tracking, vision based tracking and hybrid tracking. The sensor based tracking are further divided into optica...

  13. Fluid flow field synergy principle and its application to drag reduction

    Institute of Scientific and Technical Information of China (English)

    CHEN Qun; REN JianXun; GUO ZengYuan

    2008-01-01

    The concept of field synergy for fluid flow is introduced, which refers to the synergy of the velocity field and the velocity gradient field in an entire flow domain. Analyses show that the flow drag depends not only on the velocity and the velocity gradient fields but also on their synergy. The principle of minimum dissipation of mechanical energy is developed, which may be stated as follows: the worse the synergy between the velocity and velocity gradient fields is, the smaller the resistance becomes. Furthermore, based on the principle of minimum dissipation of mechanical energy together with conservation equations, a field synergy equation with a set of specified constraints has been established for optimizing flow processes. The optimal flow field can be obtained by solving the field synergy equation, which leads to the minimum resistance to fluid flow in the fixed flow domain. Finally, as an example, the field synergy analysis for duct flow with two parallel branches is presented. The optimized velocity distributor nearby the fork, which was designed based on the principle of minimum dissipation of mechanical energy, may reduce the drag of duct flow with two parallel branches.

  14. Decay of isotropic flow and anisotropic flow with rotation or magnetic field or both in a weakly nonlinear regime

    CERN Document Server

    Wei, Xing

    2016-01-01

    We investigate numerically the decay of isotropic, rotating, magnetohydrodynamic (MHD), and rotating MHD flows in a periodic box. The Reynolds number $Re$ defined with the box size and the initial velocity is $100$ at which the flows are in a weakly nonlinear regime, i.e. not laminar but far away from the fully turbulent state. The decay of isotropic flow has two stages, the first stage for the development of small scales and the second stage for the viscous dissipation. In the rapidly rotating flow, fast rotation induces the inertial wave and causes the large-scale structure to inhibit the development of the first stage and retard the flow decay. In the MHD flow, the imposed field also causes the large-scale structure but facilitates the flow decay in the first stage because of the energy conversion from flow to magnetic field. Magnetic Reynolds number $Rm$ is important for the dynamics of the MHD flow, namely a high $Rm$ induces the Alfv\\'en wave but a low $Rm$ cannot. In the rotating MHD flow, slower rotat...

  15. Experiments on the droplet field in multiphase pipe flow

    OpenAIRE

    Alvarado, Andrea Shmueli

    2015-01-01

    Gas-liquid flows are very common in industrial applications and many times involve three phases. Experiments are important as basis for development of 1D flow models used for design of multiphase transport systems. The experiments are either used as direct closure relation or for model validation. Currently, there is a lack of three-phase flow data on droplet entrainment. This thesis is focused on two main topics: establish relevant experimental data of the droplet flux profiles, pressure gra...

  16. Numerical simulation of cantilevered ramp injector flow fields for hypervelocity fuel/air mixing enhancement

    Science.gov (United States)

    Schumacher, Jurgen Christian

    Increasing demand for affordable access to space and high speed terrestrial transport has spawned research interest into various air-breathing hypersonic propulsion systems. Propulsion concepts such as the supersonic combustion ramjet (scramjet) and the shock-induced combustion ramjet (shcramjet) utilize oxygen freely available in the atmosphere and thereby substantially reduce the weight penalty of on-board oxidizer tankage used in rocket based systems. Of key importance to the ultimate success of an air-breathing concept is the ability to efficiently mix the fuel with atmospheric air. In the case of a hypersonic air-breather the challenge is accentuated due to the requirement of supersonic combustion. Flow velocities through the combustor on the order of thousands of meters per second provide the fuel and air with only a brief time to adequately combine. Contemporary mixing augmentation methods to address this issue have focused on fuel injection devices which promote axial vortices to enhance the mixing process. Much research effort has been expended on investigation of ramp injectors for this purpose. The present study introduces a new ramp injector design, based on the conventional ramp injector, dubbed the cantilevered ramp injector. A two-pronged numerical approach was employed to investigate the mixing performance and characteristics of the cantilevered injector consisting of, (1) comparison with conventional designs and (2) a parametric study of various cantilevered injector geometries. A laminar, three-dimensional, multispecies flowsolver was developed in generalized coordinates to solve the Navier-Stokes equations for the flow fields of injected H2 into high-enthalpy air. The scheme consists of an upwind TVD scheme for discretization of the convective fluxes coupled with a semi-implicit LU-SGS scheme for temporal discretization. Through analysis of the numerical solutions, it has been shown that the cantilevered ramp injector is a viable fuel injection

  17. Accelerated ions from pulsed-power-driven fast plasma flow in perpendicular magnetic field

    Science.gov (United States)

    Takezaki, Taichi; Takahashi, Kazumasa; Sasaki, Toru; Kikuchi, Takashi; Harada, Nob.

    2016-06-01

    To understand the interaction between fast plasma flow and perpendicular magnetic field, we have investigated the behavior of a one-dimensional fast plasma flow in a perpendicular magnetic field by a laboratory-scale experiment using a pulsed-power discharge. The velocity of the plasma flow generated by a tapered cone plasma focus device is about 30 km/s, and the magnetic Reynolds number is estimated to be 8.8. After flow through the perpendicular magnetic field, the accelerated ions are measured by an ion collector. To clarify the behavior of the accelerated ions and the electromagnetic fields, numerical simulations based on an electromagnetic hybrid particle-in-cell method have been carried out. The results show that the behavior of the accelerated ions corresponds qualitatively to the experimental results. Faster ions in the plasma flow are accelerated by the induced electromagnetic fields modulated with the plasma flow.

  18. Experimental study of humid air reverse diffusion combustion in a turbulent flow field

    Institute of Scientific and Technical Information of China (English)

    GE Bing; ZANG Shusheng; GU Xin

    2007-01-01

    Experiments were performed to investigate the differences between the propane/air turbulent diffusion reactive flows past bluff-body and the propane/humid air turbulent diffusion reactive flows in the same conditions.The velocity distributions of the non-humid reactive flow fields and the humid reactive flow fields were measured by particle image velocimetry (PIV) techniques.The temperature fields were measured by high temperature thermocouples,and NOx distributions were obtained by using gas detection instruments.The results show that although humid air reactive flow fields are similar to non-humid flow fields in general,there are some differences in the humid air combustion flow field comparing with the non-humid combustion flow field:the center of the reversed-flow region goes forward;the dimension of the reversed-flow region is smaller;the peak temperature and NOx formation are reduced.It is suggested that humid air combustion is helpful to shorten the axial length of combustors,and reduce the formation of pollutants.

  19. Correlation analysis of spatio-temporal images for estimating two-dimensional flow velocity field in a rotating flow condition

    Science.gov (United States)

    Yu, Kwonkyu; Kim, Seojun; Kim, Dongsu

    2015-10-01

    Flow velocity estimation in actual rivers using image processing technique has been highlighted for hydrometric communities in the last decades, and this technique is called Large Scale Particle Image Velocimetry (LSPIV). Although LSPIV has been successfully tested in many flow conditions, it has addressed several limitations estimating mean flow field because of difficult flow conditions such as rotating, lack of light and seeds, and noisy flow conditions. Recently, an alternative technique named STIV to use spatio-temporal images based on successively recorded images has been introduced to overcome the limitations of LSPIV. The STIV was successfully applied to obtain one-dimensional flow component in the river for estimating streamflow discharge, where the main flow direction is known. Using the 5th order of central difference scheme, the STIV directly calculated the mean angle of slopes which appeared as strips in the spatio-temporal images and has been proved to be more reliable and efficient for the discharge estimation as compared with the conventional LSPIV. However, yet it has not been sufficiently qualified to derive two-dimensional flow field in the complex flow, such as rotating or locally unsteady flow conditions. We deemed that it was because the strips in the given spatio-temporal images from not properly oriented for main flow direction are not narrow enough or clearly visible, thus the direct estimating strip slope could give erroneous results. Thereby, the STIV has been mainly applied for obtaining one-dimensional flow component. In this regard, we proposed an alternative algorithm to estimate the mean slope angle for enhancing the capability of the STIV, which used correlation coefficient between odd and even image splits from the given spatio-temporal image. This method was named CASTI (Correlation Analysis of Spatio-Temporal Image). This paper described the step-by-step procedure of the CASTI and validated its capability for estimating two

  20. Confronting an augmented reality

    OpenAIRE

    Munnerley, Danny; Bacon, Matt; Wilson, Anna,; Steele, James; Hedberg, John; Fitzgerald, Robert

    2012-01-01

    How can educators make use of augmented reality technologies and practices to enhance learning and why would we want to embrace such technologies anyway? How can an augmented reality help a learner confront, interpret and ultimately comprehend reality itself ? In this article, we seek to initiate a discussion that focuses on these questions, and suggest that they be used as drivers for research into effective educational applications of augmented reality. We discuss how multi-modal, sensorial...

  1. Mobile Augmented Reality Applications

    OpenAIRE

    Prochazka, David; Stencl, Michael; Popelka, Ondrej; Stastny, Jiri

    2011-01-01

    Augmented reality have undergone considerable improvement in past years. Many special techniques and hardware devices were developed, but the crucial breakthrough came with the spread of intelligent mobile phones. This enabled mass spread of augmented reality applications. However mobile devices have limited hardware capabilities, which narrows down the methods usable for scene analysis. In this article we propose an augmented reality application which is using cloud computing to enable using...

  2. Magnetohydrodynamic Augmented Propulsion Experiment

    Science.gov (United States)

    Litchford, Ron J.; Cole, John; Lineberry, John; Chapman, Jim; Schmidt, Harold; Cook, Stephen (Technical Monitor)

    2002-01-01

    that an MHD accelerator can be an effective augmentation system for increasing engine exhaust velocity. More specifically, the experiment is intended to show that electromagnetic effects are effective at producing flow acceleration whereas electrothermal effects do not cause unacceptable heating of the working fluid. The MHD accelerator was designed as an externally diagonalized segmented Faraday channel, which will be inserted into an existing 2-tesla electromagnet. This allows the external power to be connected through two terminals thereby minimizing the complexity and cost associated with powering each segment independently. The design of the accelerator and other components in the flow path has been completed and fabrication activities are underway. This paper provides a full description of MAPX including performance analysis, design, and test plans, and current status.

  3. Rational strategy for characterization of nanoscale particles by asymmetric-flow field flow fractionation: A tutorial

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •Underlying theory and critical parameters are introduced. •A rational workflow is proposed to optimize and refine A4F methods. •Specific optimization steps and validation parameters are delineated. •Pedagogical examples are provided to demonstrate the process. •Use and relevance of different detection modalities is addressed. -- Abstract: This tutorial proposes a comprehensive and rational measurement strategy that provides specific guidance for the application of asymmetric-flow field flow fractionation (A4F) to the size-dependent separation and characterization of nanoscale particles (NPs) dispersed in aqueous media. A range of fractionation conditions are considered, and challenging applications, including industrially relevant materials (e.g., metal NPs, asymmetric NPs), are utilized in order to validate and illustrate this approach. We demonstrate that optimization is material dependent and that polystyrene NPs, widely used as a reference standard for retention calibration in A4F, in fact represent a class of materials with unique selectivity, recovery and optimal conditions for fractionation; thus use of these standards to calibrate retention for other materials must be validated a posteriori. We discuss the use and relevance of different detection modalities that can potentially yield multi-dimensional and complementary information on NP systems. We illustrate the fractionation of atomically precise nanoclusters, which are the lower limit of the nanoscale regime. Conversely, we address the upper size limit for normal mode elution in A4F. The protocol for A4F fractionation, including the methods described in the present work is proposed as a standardized strategy to realize interlaboratory comparability and to facilitate the selection and validation of material-specific measurement parameters and conditions. It is intended for both novice and advanced users of this measurement technology

  4. Numerical simulation of flow fields and particle trajectories

    DEFF Research Database (Denmark)

    Mayer, Stefan

    2000-01-01

    A model describing the ciliary driven flow and motion of suspended particles in downstream suspension feeders is developed. The quasi-steady Stokes equations for creeping flow are solved numerically in an unbounded fluid domain around cylindrical bodies using a boundary integral formulation. The ...

  5. Mobile Augmented Reality Applications

    CERN Document Server

    Prochazka, David; Popelka, Ondrej; Stastny, Jiri

    2011-01-01

    Augmented reality have undergone considerable improvement in past years. Many special techniques and hardware devices were developed, but the crucial breakthrough came with the spread of intelligent mobile phones. This enabled mass spread of augmented reality applications. However mobile devices have limited hardware capabilities, which narrows down the methods usable for scene analysis. In this article we propose an augmented reality application which is using cloud computing to enable using of more complex computational methods such as neural networks. Our goal is to create an affordable augmented reality application suitable which will help car designers in by 'virtualizing' car modifications.

  6. Numerical Analysis of the Turbine 99 Draft Tube Flow Field Provoked by Redesigned Inlet Velocity Profiles

    International Nuclear Information System (INIS)

    In recent years, several investigations on hydraulic turbine draft tube performance have shown that the hydrodynamic flow field at the runner outlet determines the diffuser efficiency affecting the overall performance of the turbine. This flow field, for which the principal characteristics are the flow rate and the inlet swirling flow intensity, is mostly developed on turbines designed for low head (high specific velocity) and operated away from their best efficiency point. To identify factors of the flow field responsible for loosing draft- tube efficiency, the correlations between the flow pattern along the diffuser and both swirl intensity and flow rate have been examined. An analytical representation of inlet flow field has been manipulated by a Multi Island Genetic Algorithm through the automatic coupling of multidisciplinary commercial software systems in order to obtain redesigned inlet velocity profiles. This loop allowed determining the profile for which the minimum energy loss factor was reached. With different flow field patterns obtained during the optimization process it was possible to undertake a qualitative and quantitative analysis which has helped to understand how to suppress or at least mitigate undesirable draft tube flow characteristics. The direct correlation between the runner blade design and the kinematics of the swirl at the draft tube inlet should suppose the perfect coupling at the runner-draft tube interface without compromising the overall flow stability of the machine

  7. Field-scale water flow and solute transport : Swap model concepts, parameter estimation and case studies

    NARCIS (Netherlands)

    Dam, van J.C.

    2000-01-01

    Water flow and solute transport in top soils are important elements in many environmental studies. The agro- and ecohydrological model SWAP (Soil-Water-Plant-Atmosphere) has been developed to simulate simultaneously water flow, solute transport, heat flow and crop growth at field scale level. The ma

  8. Augmented Reality in Science Education

    DEFF Research Database (Denmark)

    Nielsen, Birgitte Lund; Brandt, Harald; Swenson, Hakon

    2015-01-01

    Augmented reality (AR) holds great promise as a learning tool. However, most extant studies in this field have focused on the technology itself. The poster presents findings from the first stage of the AR-sci project addressing the issue of applying AR for educational purposes. Benefits and chall......Augmented reality (AR) holds great promise as a learning tool. However, most extant studies in this field have focused on the technology itself. The poster presents findings from the first stage of the AR-sci project addressing the issue of applying AR for educational purposes. Benefits...... and challenges related to AR enhancing student learning in science in lower secondary school were identified by expert science teachers, ICT designers and science education researchers from four countries in a Delphi survey. Findings were condensed in a framework to categorize educational AR designs....

  9. Adaptive Augmented Reality: Plasticity of Augmentations

    OpenAIRE

    Ghouaiel, Nehla; Cieutat, Jean-Marc; Jessel, Jean-Pierre

    2014-01-01

    International audience An augmented reality system is used to complete the real world with virtual objects (computer generated) so they seem to coexist in the same space as the real world. The concept of plasticity [4][5] was first introduced for Human Computer Interaction (HCI). It denotes the ability of an HCI interface to fit the context of use defined by the user, the environment and the platform. We believe that plasticity is a very important notion in the domain of augmented reality....

  10. How to Determine Losses in a Flow Field: A Paradigm Shifttowards the Second Law Analysis

    Directory of Open Access Journals (Sweden)

    Heinz Herwig

    2014-05-01

    Full Text Available Assuming that CFD solutions will be more and more used to characterizelosses in terms of drag for external flows and head loss for internal flows, we suggest toreplace single-valued data, like the drag force or a pressure drop, by field information aboutthe losses. These information are gained when the entropy generation in the flow field isanalyzed, an approach that often is called second law analysis (SLA, referring to the secondlaw of thermodynamics. We show that this SLA approach is straight-forward, systematicand helpful when it comes to the physical interpretation of the losses in a flow field. Variousexamples are given, including external and internal flows, two phase flow, compressible flowand unsteady flow. Finally, we show that an energy transfer within a certain process can beput into a broader perspective by introducing the entropic potential of an energy.

  11. The Geometry and Dynamics of a Propagating Front in a Chaotic Flow Field

    Science.gov (United States)

    Paul, Mark

    There are many important problems regarding transport in complex fluid flows with implications in science, nature, and technology. Examples include the combustion of pre-mixed gases in a turbulent flow, the complex patterns of reagents in a chemical system, the spread of a forest fire, and the outbreak of an epidemic. This talk explores the transport and dynamics of a reacting species in a chaotic fluid flow field. Large-scale parallel numerical simulations are used to explore the dynamics of propagating fronts in complex three-dimensional time-dependent fluid flows for the precise conditions of the laboratory. It is shown that a chaotic flow field enhances the front propagation when compared with a purely cellular flow field. This enhancement is quantified by computing measures of the spreading rate of the products and by quantifying the complexity of the three-dimensional front geometry for a range of chaotic flow conditions.

  12. Comparision of numerical simulation and flow field visualisation using heating foil

    OpenAIRE

    Matejka Milan; Hyhlik Tomas

    2012-01-01

    Paper deals with comparison of numerical and experimental solution of the flow field of hump. Synthetic jet actuators were used to influence flow field of the hump. Visualization using heating foil was done and compared with data from numerical simulation. The hump is located in closed measurement area of Eiffel type wind tunnel. Commercial code Fluent was used to perform numerical solution.

  13. Self-consistent stationary MHD shear flows in the solar atmosphere as electric field generators

    CERN Document Server

    Nickeler, D H; Wiegelmann, T; Kraus, M

    2014-01-01

    Magnetic fields and flows in coronal structures, for example, in gradual phases in flares, can be described by 2D and 3D magnetohydrostatic (MHS) and steady magnetohydrodynamic (MHD) equilibria. Within a physically simplified, but exact mathematical model, we study the electric currents and corresponding electric fields generated by shear flows. Starting from exact and analytically calculated magnetic potential fields, we solveid the nonlinear MHD equations self-consistently. By applying a magnetic shear flow and assuming a nonideal MHD environment, we calculated an electric field via Faraday's law. The formal solution for the electromagnetic field allowed us to compute an expression of an effective resistivity similar to the collisionless Speiser resistivity. We find that the electric field can be highly spatially structured, or in other words, filamented. The electric field component parallel to the magnetic field is the dominant component and is high where the resistivity has a maximum. The electric field ...

  14. Direct measurement of the flow field around swimming microorganisms

    Science.gov (United States)

    Polin, Marco; Drescher, Knut; Goldstein, Raymond E.; Michel, Nicolas; Tuval, Idan

    2010-11-01

    Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute (˜0.3%) density excess of V. carteri over water leads to a strongly dominant Stokeslet contribution, with the widely-assumed stresslet flow only a correction to the subleading source dipole term. This implies that suspensions of V. carteri have features similar to suspensions of sedimenting particles. The flow in the region around C. reinhardtii where significant hydrodynamic interaction is likely to occur differs qualitatively from a "puller" stresslet, and can be described by a simple three-Stokeslet model.

  15. Direct measurement of the flow field around swimming microorganisms

    CERN Document Server

    Drescher, Knut; Michel, Nicolas; Polin, Marco; Tuval, Idan

    2010-01-01

    Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute ~0.3% density excess of V. carteri over water leads to a strongly dominant Stokeslet contribution, with the widely-assumed stresslet flow only a correction to the subleading source dipole term. This implies that suspensions of V. carteri have features similar to suspensions of sedimenting particles. The flow in the region around C. reinhardtii where significant hydrodynamic interaction is likely to occur differs qualitatively from a "puller" stresslet, and can be described by a simple three-Stokeslet model.

  16. Numerical simulation on coupling performance of steam flow field and electric field in capacitance sensor measuring steam wetness

    International Nuclear Information System (INIS)

    Based on the theory of dielectric polarization and hydrodynamics, using the FLUENT UDF code, the coupling performances of the steam flow field and the electric field in the capacitance sensor were numerically simulated. The standard k-ε model, wall function and SIMPLE way were used. The results show that the voltage decreases gradually from positive plate to negative plate, and the change is even; water molecule is polarized, the polarized charge appears near the plates, and there is no polarized charge in the center of sensor when the dry saturation steam flows through the capacitance sensor; the radial velocity is different from with and without electric field in the capacitance sensor, and the difference is max near the outmost plate; the electric field near the plate is smaller when there is no flow field. The results of numerical simulation match with the results of experiment. The numerical simulation model is feasibility. (authors)

  17. Single- and multi-phase flows in an electromagnetic field: energy, metallurgical, and solar applications

    International Nuclear Information System (INIS)

    Laminar MHD flows are discussed, taking into account laminar duct flows in strong magnetic fields, approximate side layer solutions for a liquid metal flow in a rectangular duct with a strong nonuniform magnetic field, applications of MHD flows between rotating disks, and unsteady magnetoaerodynamic supersonic flows past oscillating thin bodies and lifting surfaces. Other topics explored are related to MHD and HD turbulence, two-phase flows, MHD power generation and application to fission and fusion reactors, and metallurgical applications. Attention is given to Hartmann layers in slowly solidifying liquids, shaping of liquid metal cylinders, the electromagnetic force of narrow stirring inductors, high-temperature liquid metal MHD solar thermal systems, streamer dynamics in MHD generators, a tin-water Faraday generator, an analytical model for bubbly flow, the stability of two-phase liquid metal MHD channel flow, and the transition from three-dimensional to quasi-two-dimensional MHD grid turbulence

  18. Experimental study of flow field in interference area between impeller and guide vane of axial flow pump

    Institute of Scientific and Technical Information of China (English)

    张华; 施卫东; 陈斌; 曹卫东; 张启华

    2014-01-01

    Axial flow pump is a kind of typical pumps with rotor-stator interaction, thus the measurement of the flow field between impeller and guide vane would facilitate the study of the internal rotor-stator interaction mechanism. Through a structural modifi-cation of a traditional axial flow pump, the requirements of particle image velocimetry (PIV) measurement are met. Under the condition of opt.0.8Q , the axial vortex is identified between impeller hub and guide vane hub, which is developed into the main flow and to affect the movement when the relative positions of impeller and guide vane at different flow rates are the same. Besides, the development and the dissipation of the tip leakage and the passage vortex in impeller passages are mainly responsible for the difference of the flow field close to the outer rim. As the flow rate decreases, the distribution of the meridional velocities at the impeller outlet becomes more non-uniform and the radial velocity component keeps increasing. The PIV measurement results under the condition of opt.1.0Q indicate that the flow separation and the trailing vortex at the trailing edge of a blade are likely to result in a velocity sudden change in this area, which would dramatically destroy the continuity of the flow field. Moreover, the radial direction of the flow between impeller and guide vane on the measurement plane does not always point from hub to rim. For a certain position, the direction is just from rim to hub, as is affected by the location of the intersection line of the shooting section and the impeller blade on the impeller as well as the angle between the intersection line and the rotating shaft.

  19. Coherent gas flow patterns in heterogeneous permeability fields

    OpenAIRE

    Samani, Shirin

    2012-01-01

    Gas injection into saturated porous media has a high practical relevance. It is applied in groundwater remediation (air sparging), in CO2 sequestration into saline aquifers, and in enhanced oil recovery of petroleum reservoirs. This wide range of application necessitates a comprehensive understanding of gas flow patterns that may develop within the porous media and required modeling of multi-phase flow. There is an ongoing controversy in literature, if continuum models are able...

  20. Experimental and numerical studies on plasma behavior flowing across perpendicular magnetic field

    Science.gov (United States)

    Takezaki, T.; Takahashi, K.; Sasaki, T.; Kikuchi, T.; Harada, N.

    2016-05-01

    To understand particle acceleration mechanisms in a collisionless shock, we have investigated the behaviors of a one-dimensional fast plasma flow in a perpendicular magnetic field by experimental and numerical simulations in a laboratory scale experiment. The velocity of the plasma flow generated by a taper-cone-shaped plasma focus device has varied by the gradient of the perpendicular magnetic field. The plasma flow has accelerated by applying the magnetic field with the negative gradient. To clarify the behavior of the plasma flow in the perpendicular magnetic field, numerical simulations based on an electromagnetic hybrid particle-in-cell (PIC) method have been carried out. These results indicate that the magnetic field gradient affects the plasma flow velocity.

  1. Numerical simulation of electro-magnetic and flow fields of TiAl melt under electric field

    Directory of Open Access Journals (Sweden)

    Zhang Yong

    2010-08-01

    Full Text Available This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAl melt under two electric fields. FEM (Finite Element Method and APDL (ANSYS Parametric Design Language were employed to perform the simulation, model setup, loading and problem solving. The melt in molds of same cross section area with different flakiness ratio (i.e. width/depth under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field. The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1. The melt is driven bipolarly from the center in each electric field. It is also found that the pulse electric field actuates the TiAl melt to flow stronger than what the sinusoidal electric field does.

  2. Equating of Augmented Subscores

    Science.gov (United States)

    Sinharay, Sandip; Haberman, Shelby J.

    2011-01-01

    Recently, there has been an increasing level of interest in subscores for their potential diagnostic value. Haberman (2008b) suggested reporting an augmented subscore that is a linear combination of a subscore and the total score. Sinharay and Haberman (2008) and Sinharay (2010) showed that augmented subscores often lead to more accurate…

  3. Confronting an Augmented Reality

    Science.gov (United States)

    Munnerley, Danny; Bacon, Matt; Wilson, Anna; Steele, James; Hedberg, John; Fitzgerald, Robert

    2012-01-01

    How can educators make use of augmented reality technologies and practices to enhance learning and why would we want to embrace such technologies anyway? How can an augmented reality help a learner confront, interpret and ultimately comprehend reality itself ? In this article, we seek to initiate a discussion that focuses on these questions, and…

  4. Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system

    Science.gov (United States)

    Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng

    2015-12-01

    We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices.

  5. An Empirical Method for Fast Prediction of Rarefied Flow Field around a Vertical Plate

    Science.gov (United States)

    He, Tao; Wang, Jiang-Feng

    2016-06-01

    Numerical study is conducted to investigate the effects of free-stream Knudsen (Kn) number on rarefied flow field around a vertical plate employing an unstructured DSMC method, and an empirical method for fast prediction of flow-field structure at different Kn numbers in a given inflow velocity is proposed. First, the flow at a velocity 7500m/s is simulated using a perfect-gas model with free-stream Kn changing from 0.035 to 13.36. The flow-field characteristics in these cases with varying Kn numbers are analyzed and a linear-expansion phenomenon as a function of the square of Kn is discovered. An empirical method is proposed for fast flow-field prediction at different Kn based on the least-square-fitting method. Further, the effects of chemical reactions on flow field are investigated to verify the applicability of the empirical method in the real gas conditions. Three of the cases in perfect-gas flow are simulated again by introducing five-species air chemical module. The flow properties with and without chemical reactions are compared. In the end, the variation of chemical-reaction flow field as a function of Kn is analyzed and it is shown that the empirical method are also suitable when considering chemical reactions.

  6. Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system

    Science.gov (United States)

    Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng

    2015-01-01

    We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices. PMID:26687638

  7. Transport of magnetic field by a turbulent flow of liquid sodium

    International Nuclear Information System (INIS)

    We study the effect of a turbulent flow of liquid sodium generated in the von Karman geometry, on the localized field of a magnet placed close to the frontier of the flow. We observe that the field can be transported by the flow on distances larger than its integral length scale. In the most turbulent configurations, the mean value of the induced field at large distance vanishes. However, the root-mean-square (rms) value of the fluctuations increases linearly with the magnetic Reynolds number. The induced field is strongly intermittent. (authors)

  8. 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)

  9. Field programming in gravitational field-flow fractionation: a tool for fast and efficient separation of particles

    Czech Academy of Sciences Publication Activity Database

    Plocková, Jana; Matulík, František; Chmelík, Josef

    Bratislava: Polymer Institute of the Slovak Academy of Sciences, 2001, s. 68. [International Bratislava Meeting on Polymers /16./. Bratislava (SK), 09.09.2001-13.09.2001] R&D Projects: GA AV ČR IAA4031805 Institutional research plan: CEZ:AV0Z4031919 Keywords : field flow fractionation * force field programming * separation Subject RIV: CB - Analytical Chemistry, Separation

  10. Rapidly rotating spherical Couette flow in a dipolar magnetic field: an experimental study of the mean axisymmetric flow

    CERN Document Server

    Nataf, Henri-Claude; Brito, Daniel; Cardin, Philippe; Gagnière, Nadège; Jault, Dominique; Schmitt, Denys

    2007-01-01

    In order to explore the magnetostrophic regime expected for planetary cores, in which the Lorentz forces balance the Coriolis forces, experiments have been conducted in a rotating sphere filled with liquid sodium, with an imposed dipolar magnetic field (the $DTS$ setup). The field is produced by a permanent magnet enclosed in an inner sphere, which can rotate at a separate rate, producing a spherical Couette flow. The flow properties are investigated by measuring electric potentials on the outer sphere, the induced magnetic field in the laboratory frame just above the rotating outer sphere, and velocity profiles inside the liquid sodium using ultrasonic Doppler velocimetry. The present article focuses on the mean axisymmetric part of the flow. The electric potential differences measured at several latitudes can be linked to azimuthal velocities, and are indeed found to be proportional to the azimuthal velocities measured by Doppler velocimetry. The Doppler profiles show that the angular velocity of the fluid ...

  11. NUMERICAL AND EXPERIMENTAL INVESTIGATION OF BEVELED TRAILING EDGE FLOW FIELDS

    Institute of Scientific and Technical Information of China (English)

    MOSALLEM M. M.

    2008-01-01

    The characteristics of flow past beveled trailing edges attached to flat plates have been investigated numerically and experimentally. The test models used in the present study were two 2D blunt-faced flat plates having asymmetric beveled trailing edges of angles 27° and 60°. The numerical simulation results display an asymmetric wake behind the 27° beveled trailing edge and von karmen street vortices behind the 60° beveled trailing edge. The flow visualization using cavitation technique showed the same observations of the numerical simulation. Therefore, it is obvious that the trailing edge geometry has a pronounced effect on the wake development and vortex shedding. Also, it is concluded that the cavitation phenomenon can be used as a visualization technique at high flow velocities.

  12. Flow-Driven Cell Migration under External Electric Fields

    Science.gov (United States)

    Li, Yizeng; Mori, Yoichiro; Sun, Sean X.

    2015-12-01

    Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and they can migrate toward a cathode or an anode, depending on the cell type. In this Letter, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent.

  13. Evaluation of Thermal Anomalies in Multi-Boreholes Field Considering the Effects of Groundwater Flow

    OpenAIRE

    Shibin Geng; Yong Li; Xu Han; Huiliang Lian; Hua Zhang

    2016-01-01

    In this paper, the performance of multiple boreholes (multi-BHEs) field is evaluated by considering the groundwater flow. Optimization strategies are presented to mitigate thermal anomalies in the BHEs field. This study shows that groundwater flow greatly improves the heat transfer but causes thermal anomalies downstream. To overcome this problem, a heat transfer model is established for multi-boreholes based on temperature field superposition and moving finite line source model (MFLS). The M...

  14. Dielectric Resonator-Based Flow and Stopped-Flow EPR with Rapid Field Scanning: A Methodology for Increasing Kinetic Information

    Science.gov (United States)

    Sienkiewicz, Andrzej; Ferreira, Ana Maria da Costa; Danner, Birgit; Scholes, Charles P.

    1999-02-01

    We report methodology which combines recently developed dielectric resonator-based, rapid-mix, stopped-flow EPR (appropriate for small, aqueous, lossy samples) with rapid scanning of the external (Zeeman) magnetic field where the scanning is preprogrammed to occur at selected times after the start of flow. This methodology gave spectroscopic information complementary to that obtained by stopped-flow EPR at single fields, and with low reactant usage, it yielded more graphic insight into the time evolution of radical and spin-labeled species. We first used the ascorbyl radical as a test system where rapid scans triggered after flow was stopped provided "snapshots" of simultaneously evolving and interacting radical species. We monitored ascorbyl radical populations either as brought on by biologically damaging peroxynitrite oxidant or as chemically and kinetically interacting with a spectroscopically overlapping nitroxide radical. In a different biophysical application, where a spin-label lineshape reflected rapidly changing molecular dynamics of folding spin-labeled protein, rapid scan spectra were taken during flow with different flow rates and correspondingly different times after the mixing-induced inception of protein folding. This flow/rapid scan method is a means for monitoring early immobilization of the spin probe in the course of the folding process.

  15. Integrating Hypermedia Techniques with Augmented Reality Environments

    OpenAIRE

    Sinclair, Patrick

    2004-01-01

    Augmented Reality systems, which overlay virtual information over the real world, can benefit greatly from the techniques established by the Open Hypermedia research field. Storing information and links separately from a document can be advantageous for augmented reality applications and can enable the adaption of content to suit users’ preferences. This thesis explores how Open Hypermedia systems might be used as the information systems behind AR environments. This provides benefits to augme...

  16. Experimental Investigation on Liquid Metal Flow Distribution in Insulating Manifold under Uniform Magnetic Field

    Science.gov (United States)

    Miura, Masato; Ueki, Yoshitaka; Yokomine, Takehiko; Kunugi, Tomoaki

    2012-11-01

    Magnetohydrodynamics (MHD) problem which is caused by interaction between electrical conducting fluid flow and the magnetic field is one of the biggest problem in the liquid metal blanket of the fusion reactor. In the liquid metal blanket concept, it is necessary to distribute liquid metal flows uniformly in the manifold because imbalance of flow rates should affect the heat transfer performance directly, which leads to safety problem. While the manifold is insulated electrically as well as the flow duct, the 3D-MHD effect on the flowing liquid metal in the manifold is more apparent than that in straight duct. With reference to the flow distribution in this concept, the liquid metal flow in the electrical insulating manifold under the uniform transverse magnetic field is investigated experimentally. In this study, GaInSn is selected as working fluid. The experimental system includes the electrical magnet and the manifold test section which is made of acrylic resin for perfectly electrical insulation. The liquid metal flows in a non-symmetric 180°-turn with manifold, which consists of one upward channel and two downward channels. The flow rates in each channel are measured by electromagnetic flow meters for several combinations Reynolds number and Hartman number. The effects of magnetic field on the uniformity of flow distribution are cleared.

  17. Experimental Measurement of the Flow Field of Heavy Trucks

    Energy Technology Data Exchange (ETDEWEB)

    Fred Browand; Charles Radovich

    2005-05-31

    Flat flaps that enclose the trailer base on the sides and top are known to reduce truck drag and reduce fuel consumption. Such flapped-truck geometries have been studied in laboratory wind tunnels and in field tests. A recent review of wind tunnel data for a variety of truck geometries and flow Reynolds numbers show roughly similar values of peak drag reduction, but differ in the determination of the optimum flap angle. Optimum angles lie in the range 12 degrees-20 degrees, and may be sensitive to Reynolds number and truck geometry. The present field test is undertaken to provide additional estimates of the magnitude of the savings to be expected on a typical truck for five flap angles 10, 13, 16, 19, and 22 degrees. The flaps are constructed from a fiberglass-epoxy-matrix material and are one-quarter of the base width in length (about 61 cm, or 2 feet). They are attached along the rear door hinge lines on either side of the trailer, so that no gap appears at the joint between the flap and the side of the trailer The flap angle is adjusted by means of two aluminum supports. The present test is performed on the NASA Crows Landing Flight Facility at the northern end of the San Joaquin valley in California. The main runway is approximately 2400 meters in length, and is aligned approximately in a north-south direction The test procedure is to make a series of runs starting at either end of the runway. All runs are initiated under computer control to accelerate the truck to a target speed of 60 mph (96 6 km/hr), to proceed at the target speed for a fixed distance, and to decelerate at the far end of the runway. During a run, the broadcast fuel rate, the engine rpm, forward speed, elapsed time--as well as several other parameters (10 in all)--are digitized at a rate of 100 digitizations per second. Various flapped-conditions are interspersed with the ''no flaps'' control, and are sequenced in a different order on different days. Approximately 310 runs

  18. Experimental Investigation of the Internal Flow Field of Rotating Impeller Passage with Inlet Box

    Institute of Scientific and Technical Information of China (English)

    WuKeqi; HuShengli

    1995-01-01

    Using PDA and its measurement system.the flow fields at the different peripheral locations of rotating impeller passage of a diagonal fan with inlet box are measured.The results are compared with the flow field of the rotating impeller passage of the same fan without inlet box.The differences of the flow characteristics of the rotating passage at the different peripheral locations are revealed.The effects of the complex flow in the inlet box on the internal folw of the rotaing impell passage are investigated.

  19. Estimation of local and regional components of drain - flow from an irrigated field

    International Nuclear Information System (INIS)

    The contribution of regional ground water and deep percolation from a furrow irrigated field to total drain flow was estimated using salt load analysis. It was found that 64% of the drain flow comes from regional ground water flow. The electrical conductivity of the drain water was highly correlated with the drain flow rate. From the field water balance with deep percolation as estimated from the salt load analysis, using yield function derived evapotranspiration, and measured changes in root zone water storage, it was shown that 14% of the crop evapotranspiration comes from ground water during the study period. 8 figs; 5 tabs; 15 refs ( Author )

  20. 轴流式血泵流场CFD仿真%Flow field CFD analysis of axial flow blood pump

    Institute of Scientific and Technical Information of China (English)

    谢雄; 谭建平

    2014-01-01

    In the development of axial flow blood pump,the arterial partial flow field may produce an area with very low flow shear rate,so it is necessary to consider the non-Newtonian charac-teristics of blood fluid.In this paper,a model of axial flow blood pump was established,and flow and rotate-speed’s impacts on the inlet and outlet of the flow field in the blood pump were ana-lyzed through Computational Fluid Dynamics (CFD)simulation,as wel as the influence of the guide vane on the flow field.By the pump water experiment of the designed blood pump,its out-put flow and pressure were measured;the results show that the designed blood pump is consist-ent on the law with the simulation.%在轴流式血泵的研发过程中,动脉局部流场中可能产生流动剪切率非常低的区域,因此有必要考虑血液的非牛顿特性。建立了轴流式血泵模型,通过CFD仿真分析得到血泵转速和流量的变化对血泵出入口压力分布和速度分布的影响,并采用水和甘油(2∶1)的混合流体替代血液,对设计的血泵进行驱动实验,测量了轴流式血泵输出流量和压力参数。结果表明:所设计的血泵在规律上和仿真是相符的。

  1. Pollen- and seed-mediated transgene flow in commercial cotton seed production fields.

    Directory of Open Access Journals (Sweden)

    Shannon Heuberger

    Full Text Available BACKGROUND: Characterizing the spatial patterns of gene flow from transgenic crops is challenging, making it difficult to design containment strategies for markets that regulate the adventitious presence of transgenes. Insecticidal Bacillus thuringiensis (Bt cotton is planted on millions of hectares annually and is a potential source of transgene flow. METHODOLOGY/PRINCIPAL FINDINGS: Here we monitored 15 non-Bt cotton (Gossypium hirsutum, L. seed production fields (some transgenic for herbicide resistance, some not for gene flow of the Bt cotton cry1Ac transgene. We investigated seed-mediated gene flow, which yields adventitious Bt cotton plants, and pollen-mediated gene flow, which generates outcrossed seeds. A spatially-explicit statistical analysis was used to quantify the effects of nearby Bt and non-Bt cotton fields at various spatial scales, along with the effects of pollinator abundance and adventitious Bt plants in fields, on pollen-mediated gene flow. Adventitious Bt cotton plants, resulting from seed bags and planting error, comprised over 15% of plants sampled from the edges of three seed production fields. In contrast, pollen-mediated gene flow affected less than 1% of the seed sampled from field edges. Variation in outcrossing was better explained by the area of Bt cotton fields within 750 m of the seed production fields than by the area of Bt cotton within larger or smaller spatial scales. Variation in outcrossing was also positively associated with the abundance of honey bees. CONCLUSIONS/SIGNIFICANCE: A comparison of statistical methods showed that our spatially-explicit analysis was more powerful for understanding the effects of surrounding fields than customary models based on distance. Given the low rates of pollen-mediated gene flow observed in this study, we conclude that careful planting and screening of seeds could be more important than field spacing for limiting gene flow.

  2. Towards an interactive medical system by augmented reality

    OpenAIRE

    Khawla Ben Abderrahim; Mohamed Kallel; M. S. Bouhlel

    2013-01-01

    Augmented reality is a computer field that progresses rapidly. Its principle is to mix the real world and the virtual world. Many applications already use augmented reality, particularly the medical field. Medical image allows doctors to make diagnosis of the patient. This diagnosis allows him to make the best decision without committing professional mistakes that can cause problems. Hence the idea of integrating augmented reality with medical image analysis to help the doctor to make the bes...

  3. Augmented reality: a review.

    Science.gov (United States)

    Berryman, Donna R

    2012-01-01

    Augmented reality is a technology that overlays digital information on objects or places in the real world for the purpose of enhancing the user experience. It is not virtual reality, that is, the technology that creates a totally digital or computer created environment. Augmented reality, with its ability to combine reality and digital information, is being studied and implemented in medicine, marketing, museums, fashion, and numerous other areas. This article presents an overview of augmented reality, discussing what it is, how it works, its current implementations, and its potential impact on libraries. PMID:22559183

  4. Calculation of flow distribution in air reverse circulation bit interior fluid field by simplifying air flow model

    Institute of Scientific and Technical Information of China (English)

    Shuqing HAO; Hongwei HUANG; Kun YIN

    2007-01-01

    By simplifying the characters in the air reverse circulation bit interior fluid field, the authors used air dynamics and fluid mechanics to calculate the air distribution in the bit and obtained an equation of flow distribution with a unique resolution. This study will provide help for making certain the bit parameters of the bit structure effectively and study the air reverse circulation bit interior fluid field character deeply.

  5. Field performance of the heat pulse flow meter: Experiences and recommendations

    Science.gov (United States)

    Busse, J.; Paillet, F. L.; Hossack, A.; Bringemeier, D.; Scheuermann, A.; Li, L.

    2016-03-01

    A large extent of groundwater flow in fractured aquifers follows fractures and cleats. The heat pulse flow meter allows the localisation and quantification of in- and outflow along borehole profiles through field measurements and subsequent inverse modelling. In this paper the method is presented and its feasibility is discussed based on the experiences gained from two different field sites. Field work was undertaken on two sites on the East Coast of Australia under different conditions leading to different outcomes. The experiences with the heat pulse flow meter method and concluding recommendations are reported to help improve the performance of the method.

  6. Transport of magnetic field by a turbulent flow of liquid sodium

    OpenAIRE

    Volk, R.; Ravelet, F.; Monchaux, R.; Berhanu, M.; Chiffaudel, A.; Daviaud, F; Odier, Ph.; Pinton, J. F.; Fauve, S.; Mordant, N.; Petrelis, F.

    2006-01-01

    We study the effect of a turbulent flow of liquid sodium generated in the von K\\'arm\\'an geometry, on the localized field of a magnet placed close to the frontier of the flow. We observe that the field can be transported by the flow on distances larger than its integral length scale. In the most turbulent configurations, the mean value of the field advected at large distance vanishes. However, the rms value of the fluctuations increases linearly with the magnetic Reynolds number. The advected...

  7. Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system

    OpenAIRE

    Sebastian Altmeyer; Younghae Do; Ying-Cheng Lai

    2015-01-01

    We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. W...

  8. A coupled three dimensional model of vanadium redox flow battery for flow field designs

    International Nuclear Information System (INIS)

    A 3D (three-dimensional) model of VRB (vanadium redox flow battery) with interdigitated flow channel design is proposed. Two different stack inlet designs, single-inlet and multi-inlet, are structured in the model to study the distributions of fluid pressure, electric potential, current density and overpotential during operation of VRB cell. Electrolyte flow rate and stack channel dimension are proved to be the critical factors affecting flow distribution and cell performance. The model developed in this paper can be employed to optimize both VRB stack design and system operation conditions. Further improvements of the model concerning current density and electrode properties are also suggested in the paper. - Highlights: • A coupled three-dimensional model of vanadium redox flow cell is proposed. • Interdigitated flow channels with two different manifold designs are simulated. • Manifold structure affects uniformity of distribution patterns significantly. • Increased electrolyte flow rate improves cell performance for both designs. • Decreased channel size and enlarged land width enhance cell voltage

  9. Colloidal layers in magnetic fields and under shear flow

    International Nuclear Information System (INIS)

    The behaviour of colloidal mono- and bilayers in external magnetic fields and under shear is discussed and recent progress is summarized. Superparamagnetic colloidal particles form monolayers when they are confined to a air-water interface in a hanging water droplet. An external magnetic field allows us to tune the strength of the mutual dipole-dipole interaction between the colloids and the anisotropy of the interaction can be controlled by the tilt angle of the magnetic field relative to the surface normal of the air-water interface. For sufficiently large magnetic field strength crystalline monolayers are found. The role of fluctuations in these two-dimensional crystals is discussed. Furthermore, clustering phenomena in binary mixtures of superparamagnetic particles forming fluid monolayers are predicted. Finally, we address sheared colloidal bilayers and find that the orientation of confined colloidal crystals can be tailored by a previously applied shear direction

  10. Gravitational flow of a thin film of liquid metal in a strong magnetic field

    International Nuclear Information System (INIS)

    The influence of a poloidal magnetic field of the spherical Tokamak on super thin (h ≈ 0.1 mm) film flow of liquid metal driven by gravity over the surface of the cooled divertor plate is addressed. The experimental setup developed at the Institute of Physics, University of Latvia (IPUL) is described, which makes it possible to drive and visualize such liquid metal flows in the solenoid of the superconducting magnet “Magdalena”. As applied to the above setup, the magnetic field effect on the operation of the capillary system of liquid metal flow distribution (CSFD) is evaluated by using molten metal (lithium or eutectic InGaSn alloy) with a very small linear flowrate q ≤ 1 mm2/s, spread uniformly across the substrate. The magnetic field effect on the main parameters of the fully developed film flow is estimated for the above-mentioned liquid metals. An approximation technique has been proposed to calculate the development of the gravitational film flow. A non-linear differential second order equation has been derived, which describes the variation of the film flow thickness over the substrate length versus the flowrate q, magnetic field B and the substrate sloping α. Results of InGaSn film flow observations in a strong (B = 4 T) poloidal magnetic field are presented. Analysis of the video records evidences of experimental realization of a stable stationary film flow at width-uniform supply of InGaSn

  11. Gravitational flow of a thin film of liquid metal in a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Platacis, E.; Flerov, A.; Klukin, A.; Ivanov, S.; Sobolevs, A.; Shishko, A. [Institute of Physics, University of Latvia, 32 Miera Street, Salaspils LV-2169 (Latvia); Zaharov, L., E-mail: zakharov@pppl.gov [Princeton University, PPPL, MS-27, P.O. Box 451, Princeton, NJ 08543 (United States); Gryaznevich, M. [Tokamak Solutions UK Ltd., Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2014-12-15

    The influence of a poloidal magnetic field of the spherical Tokamak on super thin (h ≈ 0.1 mm) film flow of liquid metal driven by gravity over the surface of the cooled divertor plate is addressed. The experimental setup developed at the Institute of Physics, University of Latvia (IPUL) is described, which makes it possible to drive and visualize such liquid metal flows in the solenoid of the superconducting magnet “Magdalena”. As applied to the above setup, the magnetic field effect on the operation of the capillary system of liquid metal flow distribution (CSFD) is evaluated by using molten metal (lithium or eutectic InGaSn alloy) with a very small linear flowrate q ≤ 1 mm{sup 2}/s, spread uniformly across the substrate. The magnetic field effect on the main parameters of the fully developed film flow is estimated for the above-mentioned liquid metals. An approximation technique has been proposed to calculate the development of the gravitational film flow. A non-linear differential second order equation has been derived, which describes the variation of the film flow thickness over the substrate length versus the flowrate q, magnetic field B and the substrate sloping α. Results of InGaSn film flow observations in a strong (B = 4 T) poloidal magnetic field are presented. Analysis of the video records evidences of experimental realization of a stable stationary film flow at width-uniform supply of InGaSn.

  12. Numerical simulation of influence of feed position on flow field

    International Nuclear Information System (INIS)

    In order to study the influence of feed position on the counter-current in gas centrifuge, direct simulation Monte-Carlo (DSMC) method was chosen to simulation the rarefied region of gas centrifuge. By setting Iguassu centrifuge model and variable hard sphere (VHS) model, the flow distributions of different feed positions were acquired. The analysis of the calculation results notes the following flow phenomena: In case of radial feed, the region near the feed outlet is largely influenced by the feed condition. The expansion of jet results in the hypothermic region. Near the boundary of effluent, due to the fast peripheral velocity, pressure gradient is large, which results in the slow radial velocity and the high temperature. The axial translation of the jet results in the axial translation of the flow distributions. With the increase of the radius of feed, the region of expansion near the feed reduces and the lowest temperature of the hypothermic region rises. Near the boundary of effluent, with the increase of the radius of feed, the temperature and the radial velocity fall. (authors)

  13. Effect Of Steel Flow Control Devices On Flow And Temperature Field In The Tundish Of Continuous Casting Machine

    Directory of Open Access Journals (Sweden)

    Sowa L.

    2015-06-01

    Full Text Available The mathematical model and numerical simulations of the liquid steel flow in a tundish are presented in this paper. The problem was treated as a complex and solved by the finite element method. One takes into consideration in the mathematical model the changes of thermophysical parameters depending on the temperature. The single-strand tundish is used to casting slabs. The internal work space of the tundish was modified by flow control devices. The first device was a pour pad situated in the pouring tundish zone. The second device was a dam. The third device was a baffle with three holes. The dam and baffle were placed in the tundish at different positions depending on the variant. The main purpose of using these was to put barriers in the steel flow path as well as give directional metal flow upwards which facilitated inclusion floatation. The interaction of flow control devices on hydrodynamic conditions was received from numerical simulations. As a result of the computations carried out, the liquid steel flow and steel temperature fields were obtained. The influences of the tundish modifications on the velocity fields in liquid phase of the steel were estimated, because these have essential an influence on high-quality of a continuous steel cast slab.

  14. Can core flows inferred from geomagnetic field models explain the Earth's dynamo?

    Science.gov (United States)

    Schaeffer, N.; Silva, E. Lora; Pais, M. A.

    2016-02-01

    We test the ability of large-scale velocity fields inferred from geomagnetic secular variation data to produce the global magnetic field of the Earth. Our kinematic dynamo calculations use quasi-geostrophic (QG) flows inverted from geomagnetic field models which, as such, incorporate flow structures that are Earth-like and may be important for the geodynamo. Furthermore, the QG hypothesis allows straightforward prolongation of the flow from the core surface to the bulk. As expected from previous studies, we check that a simple QG flow is not able to sustain the magnetic field against ohmic decay. Additional complexity is then introduced in the flow, inspired by the action of the Lorentz force. Indeed, on centennial timescales, the Lorentz force can balance the Coriolis force and strict quasi-geostrophy may not be the best ansatz. When our columnar flow is modified to account for the action of the Lorentz force, magnetic field is generated for Elsasser numbers larger than 0.25 and magnetic Reynolds numbers larger than 100. This suggests that our large-scale flow captures the relevant features for the generation of the Earth's magnetic field and that the invisible small-scale flow may not be directly involved in this process. Near the threshold, the resulting magnetic field is dominated by an axial dipole, with some reversed flux patches. Time dependence is also considered, derived from principal component analysis applied to the inverted flows. We find that time periods from 120 to 50 yr do not affect the mean growth rate of the kinematic dynamos. Finally, we note that the footprint of the inner core in the magnetic field generated deep in the bulk of the shell, although we did not include one in our computations.

  15. Forecasting change of the magnetic field using core surface flows and ensemble Kalman filtering

    International Nuclear Information System (INIS)

    Complete text of publication follows. Accurate forecasting of the change of the Earth's internal magnetic field over short intervals of time (e.g. less than five years) has many applications for government, academic and commercial users. Forecasting can be achieved by making a number of reasonable assumptions about how the main field interacts with the flow in the liquid outer core. In particular, the magnetic field can be considered to be entrained in the large scale flow along the core-mantle boundary surface over short time periods, giving rise to measurable change of the field at the Earth's surface. The observed change (or secular variation) at or above the surface of the Earth can thus be inverted to produce flow models; these can be used to propagate fluid parcels threaded by the field forwards in time to forecast the non-linear change of the magnetic field. In addition to prediction of field change by flow models, it would be advantageous to include new observations of the field from satellite measurements or ground-based observatories. We therefore present a method using Ensemble Kalman Filtering (EnKF) to produce an optimal assimilation between magnetic field change as forecast from core flow models and direct observations of the field. We show, by assuming a steady flow and assimilating field observations annually, it is possible to produce a forecast over five years with less than 20nT root mean square difference from the 'true' field. The EnKF method also allows for a sensitivity analysis of the field models to noise and for uncertainty within the physical representation.

  16. Separation and characterization of poly(tetrafluoroethylene) latex particles by asymmetric flow field flow fractionation with light-scattering detection.

    Science.gov (United States)

    Collins, Melissa E; Soto-Cantu, Erick; Cueto, Rafael; Russo, Paul S

    2014-04-01

    Poly(tetrafluoroethylene) (PTFE) latex particles have been analyzed and sorted according to size using asymmetric flow field flow fractionation (AF4) coupled with multiple-angle light scattering (MALS). Characterization of fractions by regular and depolarized dynamic light scattering confirmed that smaller particles elute prior to larger ones, as expected for field flow fractionation. The measured radii of the optically and geometrically anisotropic particles are consistent with those determined from transmission electron microscopy (TEM). A certain amount of heterogeneity remains in the fractions, but their uniformity for use as diffusion probes is improved. Full characterization of PTFE colloids will require a difficult assessment of the distribution, even within fractions, of the optical anisotropy. A general method to obtain number versus size distributions is presented. This approach is valid even when an online concentration detector is not available or ineffective. The procedure is adaptable to particles of almost any regular shape. PMID:24635125

  17. Numerical Investigation Of Surface Roughness Effects On The Flow Field In A Swirl Flow

    OpenAIRE

    SAKİN, Ali; Karagöz, İrfan

    2014-01-01

    The aim of this study is to investigate axial and tangential velocity profiles, turbulent dissipation rate, turbulent kinetic energy and pressure losses under the influence of surface roughness for the swirling flow in a cyclone separator. The governing equations for this flow were solved by using Fluent CFD code. First, numerical analyses were run to verify numerical solution and domain with experimental results. Velocity profiles, turbulent parameters and pressure drops were calculated by i...

  18. Scour and flow field around a spur dike in a 90° bend

    Institute of Scientific and Technical Information of China (English)

    Majid FAZLI; Masoud GHODSIAN; Seyed Ali Akbar Salehi NEYSHABOURI

    2008-01-01

    Spur dike is an important element in river training that creates rapid variations in flow field,sediment transport and bed topography.The mechanism of flow and sediment transport in a channel bend is very complex,especially when a spur dike is constructed in a bend.Most of previous investigations on flow behavior and scour around spur dike were carried out in straight channels.In this paper results of experiments on flow field and scour around a spur dike in a 90 degree channel bend are presented.Sand with uniform grain size was used as the bed material.Experiments were conducted for different locations and different lengths of spur dikes at the bend with different values of discharge.The three dimensional flow fields around a spur dike were investigated.The maximum depth of scour was correlated to the Froude numbers,lengths and the locations of spur dike in the bend.

  19. LDA measurement of the passage flow field in a 3-D airfoil cascade

    Science.gov (United States)

    Stauter, R. C.; Fleeter, S.

    1986-01-01

    Three-dimensional internal flow computational models are currently being developed to predict the flow through turbomachinery blade rows. For these codes to be of quantitative value, they must be verified with data obtained in experiments which model the fundamental flow phenomena. In this paper, the complete three-dimensional flow field through a subsonic annular cascade of cambered airfoils is experimentally quantified. In particular, detailed three-dimensional data are obtained to quantify the inlet velocity profile, the cascade passage velocity field, and the exit region flow field. The primary instrumentation for acquiring these data is a single-channel Laser Doppler Anemometer operating in the backscatter mode, with chordwise distributions of airfoil surface static pressure taps also utilized. Appropriate data are correlated with predictions from the MERIDL/TSONIC codes.

  20. An experimental investigation of circulation control flow fields using holographic interferometry

    Science.gov (United States)

    Bachalo, William D.

    1982-01-01

    Experiments are presented which were conducted on flow fields produced by a circulation control airfoil utilizing the Coanda effect at the trailing edge. The application of holographic interferometry to obtain both visualization and quantitative data on the flow field about a circulation control airfoil at transonic flow speed is covered. A brief description of the flow model and measurement techniques is given. The data reduction procedure, results, and interpretation are presented. The results have provided a good deal of information on the character of the flow field, particularly in the neighborhood of the trailing edge. As to the airfoil design, it is apparent that improved performance can be achieved if jet detachment is delayed. Another design improvement would involve the development of an optimum trailing-edge shape for the expected operating Mach and Reynolds number ranges.

  1. Fuel density effect on near nozzle flow field in small laminar coflow diffusion flames

    KAUST Repository

    Xiong, Yuan

    2015-01-01

    Flow characteristics in small coflow diffusion flames were investigated with a particular focus on the near-nozzle region and on the buoyancy force exerted on fuels with densities lighter and heavier than air (methane, ethylene, propane, and n-butane). The flow-fields were visualized through the trajectories of seed particles. The particle image velocimetry technique was also adopted for quantitative velocity field measurements. The results showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle, emphasizing the importance of the relative density of the fuel to that of the air on the flow-field. Nozzle heating influenced the near-nozzle flow-field particularly among lighter fuels (methane and ethylene). Numerical simulations were also conducted, focusing specifically on the effect of specifying inlet boundary conditions for fuel. The results showed that a fuel inlet boundary with a fully developed velocity profile for cases with long tubes should be specified inside the fuel tube to permit satisfactory prediction of the flow-field. The calculated temperature fields also indicated the importance of the selection of the location of the inlet boundary, especially in testing various combustion models that include soot in small coflow diffusion flames. © 2014 The Combustion Institute.

  2. Postreduction Breast Augmentation

    OpenAIRE

    Hidalgo, David A.; Doft, Melissa A.

    2015-01-01

    Background: Most breast reduction patients are highly satisfied after surgery. However, there is a subset of women who seek breast augmentation years later to restore lost volume chiefly associated with weight loss and postpartum changes. Breast shape and overall aesthetics are often revised at the same time. Methods: A retrospective review was performed of 2 surgeons’ experiences with post-reduction breast augmentation. Twenty patients were identified between 2002 and 2014. An in-depth chart...

  3. Transaxillary Endoscopic Breast Augmentation

    OpenAIRE

    Sim, Hyung-Bo

    2014-01-01

    The axillary technique is the most popular approach to breast augmentation among Korean women. Transaxillary breast augmentation is now conducted with sharp electrocautery dissection under direct endoscopic vision throughout the entire process. The aims of this method are clear: both a bloodless pocket and a sharp non-traumatic dissection. Round textured or anatomical cohesive gel implants have been used to make predictable well-defined inframammary creases because textured surface implants d...

  4. Marketing and Augmented Reality

    OpenAIRE

    Zelený, Martin

    2010-01-01

    The main goal of this diploma thesis is to identify the usage of augmented reality in contemporary marketing practice and the expectations of marketers for the future use. This will be achieved by conducting a quantitative and qualitative research among existing creative and advertising companies. Secondary goal is introducing the concept of augmented reality from the theoretical point of view and also description of potential utilization based on known examples. The tools for the practical p...

  5. Augmented Reality im Techniktraining

    OpenAIRE

    Schack, Thomas; Heinen, Thomas; Hermann, Thomas

    2007-01-01

    In den letzten Jahren wurden in Bereichen wie Robotik, Telemanipulation und Militär neue Technologien entwickelt, die als Augmented Reality (Erweiterte Realität) (Milgram et al., 1994) bezeichnet werden. Durch Augmented Reality wird die Leistungs fähigkeit der beteiligten Menschen nachweisbar unterstützt. Dabei wird die Realität eines Agenten computergestützt mit virtueller Information - auf visueller, akustischer oder taktiler Basis - in Echtzeit überlagert (erweitert). Die wesentliche Eig...

  6. A RHEOLOGICAL MODEL FOR POLYMER MELTS WITH INTERNAL STRUCTURE IN FLOW FIELDS

    Institute of Scientific and Technical Information of China (English)

    Chi-Xing Zhou

    1999-01-01

    Conceptually, an imagined conformation ellipsoid is supposed to represent the shape of a polymer chain for polymer melts in flow fields and to be equivalent to the volume element in a mathematical sense in continuum mechanics. A power law dependence of shear modulus of polymer melts on detC, referred to as envelope volume, is proposed. Based on those assumptions and the non-linear relation of shear modulus, a phenomenological viscoelastic model is derived. The model is tested in simple shear flow, simple elongational flow, oscillatory shear flow, and relaxation process after flow suddenly stopped. The results show that the model works well to predict the change of internal structure and viscoelastic performance of polymer melts in flow fields.

  7. Investigation of the Stage Performance and Flow Fields in a Centrifugal Compressor with a Vaneless Diffuser

    Directory of Open Access Journals (Sweden)

    Ahti Jaatinen-Värri

    2014-01-01

    Full Text Available The effect of the width of the vaneless diffuser on the stage performance and flow fields of a centrifugal compressor is studied numerically and experimentally. The diffuser width is varied by reducing the diffuser flow area from the shroud side (i.e., pinching the diffuser. Seven different diffuser widths are studied with numerical simulation. In the modeling, the diffuser width b/b2 is varied within the range 1.00 to 0.50. The numerical results are compared with results obtained in previous studies. In addition, two of the diffusers are further investigated with experimental measurement. The main finding of the work is that the pinch reduces losses in the impeller associated with the tip-clearance flow. Furthermore, it is shown that a too large width reduction causes the flow to accelerate excessively, resulting in a highly nonuniform flow field and flow separation near the shroud.

  8. Flow field determination at axial pump impeller tip section

    International Nuclear Information System (INIS)

    In most applications the principal limitation on the performance of an axial-flow pump is its cavitation-free operating range, characterized by the nett positive suction head (NPSH). The adverse effects of cavitation are not restricted to impaired performance; noise and vibration levels tend to increase and mechanical integrity of components can be jeopardised, sometimes severely. Cavitation may occur in the inlet region or, in some instances, in the stator blades; however the most usual source of cavitation occurrence is the impeller blading, specifically the tip section

  9. CFD Simulation of the Flow Field Inside Screw Powder Feeder

    Institute of Scientific and Technical Information of China (English)

    SHI Yang-he; SHAO Zong-heng

    2011-01-01

    A screw powder feeder is an important device for industrial applications. There are many parameters which affect the performance of the screw powder feeder, such as the shapes of the helical screw impeller, the number of screw pitches, etc. This paper presents an analysis of a gas-solid two-phase through screw powder feeder by using a commercial Computational Fluid Dynamics(CFD) code, Fluent. The K-ε model is used to simulate gas flow. Particle trajectory is obtained by the use of a discrete phase model. The results show the effects of gas velocity and panicle size on the transportation performance.

  10. Control of Meridional Flow by a Non-Uniform Rotational Magnetic Field

    Science.gov (United States)

    Mazuruk, Konstantin; Ramachandran, Narayanan

    1999-01-01

    The diffusive mass transfer of species during crystal growth in vertical ampoules is significantly affected by fluid flow in the liquid mother phase (melt). For electrically conductive melts, an elegant way of remotely inducing and controlling this flow is by utilizing a uniform rotational magnetic field (RMF) in the transverse direction. It induces an azimuthal flow which tends to homogenize the thermal and solutal fields. The rotating field also reduces the diffusion boundary layer, stabilizes temperature fluctuations, and promotes better overall crystal growth. For moderate strengths of the applied magnetic field (2-20 m Tesla) with frequencies of up to 400 Hz, the induced secondary meridional flow becomes significant. It typically consists of one roll at the bottom of the liquid column and a second roll (vortex) at the top. The flow along the centerline (ampoule axis) is directed from the growing solid (interface) towards the liquid (melt). In case of convex interfaces (e.g. in floating zone crystal growth) such flow behavior is beneficial since it suppresses diffusion at the center. However, for concave interfaces (e.g. vertical Bridgman crystal growth) such a flow tends to exacerbate the situation in making the interface shape more concave. It would be beneficial to have some control of this meridional flow- for example, a single recirculating cell with controllable direction and flow magnitude will make this technique even more attractive for crystal growth. Such flow control is a possibility if a non-uniform PNE field is utilized for this purpose. Although this idea has been proposed earlier, it has not been conclusively demonstrated so far. In this work, we derive the governing equations for the fluid dynamics for such a system and obtain solutions for a few important cases. Results from parallel experimental measurements of fluid flow in a mercury column subjected to non-uniform RMF will also be presented.

  11. Confronting an augmented reality

    Directory of Open Access Journals (Sweden)

    John Hedberg

    2012-08-01

    Full Text Available How can educators make use of augmented reality technologies and practices to enhance learning and why would we want to embrace such technologies anyway? How can an augmented reality help a learner confront, interpret and ultimately comprehend reality itself? In this article, we seek to initiate a discussion that focuses on these questions, and suggest that they be used as drivers for research into effective educational applications of augmented reality. We discuss how multi-modal, sensorial augmentation of reality links to existing theories of education and learning, focusing on ideas of cognitive dissonance and the confrontation of new realities implied by exposure to new and varied perspectives. We also discuss connections with broader debates brought on by the social and cultural changes wrought by the increased digitalisation of our lives, especially the concept of the extended mind. Rather than offer a prescription for augmentation, our intention is to throw open debate and to provoke deep thinking about what interacting with and creating an augmented reality might mean for both teacher and learner.

  12. Trends in Polymer and Particle Characterization by Microfluidic Field-Flow Fractionation Methods: Science or Business?

    Czech Academy of Sciences Publication Activity Database

    Janča, Josef; Sobota, Jaroslav

    2014-01-01

    Roč. 19, 16 May (2014), s. 296-308. ISSN 1023-666X R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : Asymmetrical flow FFF * Electrical FFF * Field- flow fractionation * Flow FFF * Microelectrical FFF * Microfluidic channels * Microthermal FFF * Miniaturization and resolution * Polymers and particles separation * Sedimentation FFF * Technical benefits of microchannels * Thermal FFF Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.264, year: 2014

  13. EFFECT OF MAGNETIC FIELD ON BLOOD FLOW THROUGH AN ARTERY: A NUMERICAL MODEL

    OpenAIRE

    J Misra; Shit, G.

    2007-01-01

    In this paper we have investigated the unsteady flow of blood by treating it as an incompressible, Newtonian, electrically conducting fluid in a straight segment of an elastic artery subject to a uniform transverse magnetic field. The problem is solved numerically with the theoretical assumption of 'local flow' model [?]. A sinusoidal variation of the arterial wall motion and a pulsatile pressure gradient have been studied. An implicit finite difference technique is used to analyze the flow. ...

  14. Influence of Feeding Mode on Flow and Temperature Field for Twin Roll Strip Casting Process

    Institute of Scientific and Technical Information of China (English)

    MIAO Yu-chuan; XU Jian-zhong; WANG Guo-dong; LIU Xiang-hua

    2003-01-01

    A three-dimensional finite element method was developed to simulate the fluid flow, heat transfer and solidification for twin roll strip casting. An improved two-equation κ-ε model was used to incorporate the turbulence in fluid flow. The influence of vertical feeding and submerged entry nozzle feeding on the flow and temperature field was discussed. The optimum submersion depth and entry angle of submerged nozzle were obtained through comparison of the simulation results.

  15. Field-scale water flow and solute transport : Swap model concepts, parameter estimation and case studies

    OpenAIRE

    Van Dam

    2000-01-01

    Water flow and solute transport in top soils are important elements in many environmental studies. The agro- and ecohydrological model SWAP (Soil-Water-Plant-Atmosphere) has been developed to simulate simultaneously water flow, solute transport, heat flow and crop growth at field scale level. The main features and theoretical concepts of SWAP are described.A serious limitation of many model applications is the availability of accurate input parameters. With the rapid increase of processor cal...

  16. Numerical Simulation of a Dual Pulse Solid Rocket Motor Flow Field

    OpenAIRE

    Afroz Javed; Manna, P; Debasis Chakraborty

    2012-01-01

    Numerical simulations are carried out for the internal flow field of a dual pulse solid rocket motor port to understand the flow behaviour. Three dimensional Reynolds Averaged Navier Stokes equations are solved alongwith shear stress transport turbulence model using commercial code. The combustion gas is assumed as a mixture of alumina and gases and single phase flow calculations are done with the thermo chemical properties provided for the mixture. The simulation captures all the essential f...

  17. Experimental Study of Plasma Actuator Effects on Flow Field Separation Bubble around Blunt Flat Plate

    OpenAIRE

    Saeed Kavousfar; Esmaeil Esmaeilzadeh; hossein mahdavy moghaddam; Sohrab Gholamhosein Pouryoussefi; Masoud Mirzaei

    2016-01-01

    In this paper, the air flow around a blunt flat plate with a rounded leading edge has been experimentally examined with and without the presence of a plasma actuator. Tests have been conducted with Reynolds numbers ranging from 104 to 105. Significant phenomena in this flow field is the flow separation at the leading edge of the body, which called separation bubble. There are two considerably dimensionless parameters in this experiment. One of them is the leading edge radius ratio...

  18. High Resolution Multispectral Flow Imaging of Cells with Extended Depth of Field Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Proposed is the development the extended depth of field (EDF) or confocal like imaging capabilities of a breakthrough multispectral high resolution imaging flow...

  19. Integrated PEMFC Flow Field Design Concept for Gravity Independent Passive Water Removal Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ElectroChem proposes a Phase II program to advance its very successful SBIR Phase I PEM fuel cell (PEMFC) program. In Phase I, the unique integrated-flow-field...

  20. Numerical study of flow field in high-speed rotational cylinder

    International Nuclear Information System (INIS)

    For a closed short cylinder in a high-speed rotational condition, the max. Mach number reaches about 7 in the flow field. The equilibrium state of the flow field in this condition is a very important problem, which requires to be solved inevitably in some engineering. A method of numerical analysis was used in this study. A cylindrical coordinate system, a second-order upwind scheme, and the total energy model were also employed. The flow field of a short cylinder in closed and high-speed rotational condition was studied by 3D numerical method. The preliminary study shows that physical results can be obtained only in certain computing condition. In this case, the flow field of the short cylinder in closed and high-speed rotational condition is able to maintain rigid body rotational state when it reaches equilibrium state. (authors)

  1. Study on refueling flow field of CITP-Ⅱ tritium production irradiation device

    International Nuclear Information System (INIS)

    The paper introduces the structure of CITP-Ⅱ tritium production irradiation device, presents the basic process of refueling breeders, studies the device's Solid-Gas phase flow, and computes the flow field parameters, such as pressure, velocity, and buoyancy. The result shows that the reliable structural design and reasonable gas differential pressure could realize the online refueling of irradiation device. (authors)

  2. Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

    Science.gov (United States)

    Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

    2015-12-01

    Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

  3. Effect of non-uniform mean flow field on acoustic propagation problems in computational aeroacoustics

    DEFF Research Database (Denmark)

    Si, Haiqing; Shen, Wen Zhong; Zhu, Wei Jun

    2013-01-01

    Acoustic propagation in the presence of a non-uniform mean flow is studied numerically by using two different acoustic propagating models, which solve linearized Euler equations (LEE) and acoustic perturbation equations (APE). As noise induced by turbulent flows often propagates from near field t...

  4. Field evidence for buoyancy-driven water flow in a Sphagnum dominated peat bog

    NARCIS (Netherlands)

    Adema, E.B.; Baaijens, G. J.; van Belle, J.; Rappoldt, C.; Grootjans, A. P.; Smolders, A. J. P.

    2006-01-01

    Nocturnal buoyancy-driven water flow in bogs is proposed as a mechanism to replenish the nutrient availability in the top of the acrotelm. In an earlier paper, we provided evidence for buoyancy-driven water flow on theoretical and experimental grounds. In this paper, field evidence is given for the

  5. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    Energy Technology Data Exchange (ETDEWEB)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard [Institute of Fluid Dynamics, ETH Zurich, 8092 Zurich (Switzerland)

    2014-08-15

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re{sub D} = 18 100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data.

  6. Droplet rotation model apply in steam uniform flow and gravitational field

    International Nuclear Information System (INIS)

    The mechanism droplet movement behavior and the qualitative description of droplet trajectory in the steam uniform flow field in the gravitational field were researched with droplet rotation model. According to the mechanism of gravitational field and uniform flow fields, the effects on droplets movement were analyzed and the importance of lift forces was also discussed. Finally, a general trajectory and mechanism of the droplets movement was derived which lays the groundwork for the qualitative analysis of the single-drop model and could be general enough to be used in many applications. (authors)

  7. Does erythropoietin augment noise induced hearing loss?

    DEFF Research Database (Denmark)

    Frederiksen, Birgitte Lidegaard; Cayé-Thomasen, Per; Lund, Søren Peter;

    2007-01-01

    in fact augment noise-induced hearing loss. This is contradictory to the beneficial effect of EPO reported by the vast majority of studies on stressed neural tissues. EPO administration may alter the blood flow dynamics of the cochlear vascular bed during or after noise exposure, by a potential...

  8. The effect of magnetic field on mean flow generation by rotating two-dimensional convection

    CERN Document Server

    Currie, Laura K

    2016-01-01

    Motivated by the significant interaction of convection, rotation and magnetic field in many astrophysical objects, we investigate the interplay between large-scale flows driven by rotating convection and an imposed magnetic field. We utilise a simple model in two dimensions comprised of a plane layer that is rotating about an axis inclined to gravity. It is known that this setup can result in strong mean flows; we numerically examine the effect of an imposed horizontal magnetic field on such flows. We show that increasing the field strength in general suppresses the time-dependent mean flows, but in some cases it organises them leading to stronger time-averaged flows. Further, we discuss the effect of the field on the correlations responsible for driving the flows and the competition between Reynolds and Maxwell stresses. A change in behaviour is observed when the (fluid and magnetic) Prandtl numbers are decreased. In the smaller Prandtl number regime, it is shown that significant mean flows can persist even ...

  9. Computational analysis of flow field around Ahmed car model passing underneath a flyover

    Science.gov (United States)

    Musa, Md Nor; Osman, Kahar; Hamat, Ab Malik A.

    2012-06-01

    A flow structure around a ground vehicle has been studied by many researchers using numerous methods, either computational or experimental. However, no analysis of flow field generated by a car passing under a flyover has been carried out. One of the famous simplified models of a car is the Ahmed body that has been established to investigate the influence of the flow structure on the drag. In this paper, we investigate a flow field around Ahmed body of a single cruising condition as the vehicle passes under a flyover, using a computational method with RANS equation. The main objective of this paper is to evaluate the turbulence kinetic energy and velocity magnitude developed within the wall boundary created by the flyover, to the air flow field that is generated by the Ahmed reference car. It was observed that the simulated airflow passes the vehicle was bounded by the wall of the flyover and consequently changes the pattern of the flow field. Understanding the characteristic of this flow field under a flyover is essential if one wants to maximize the recovery of the dissipated energy which, for example, can be used to power a small vertical-axis wind turbine to produce and store electrical energy for lighting under the flyover.

  10. Numerical Simulation of Coupled Molten Steel Flow and Temperature Fields in Compact Strip Production Casting

    Institute of Scientific and Technical Information of China (English)

    LIU Xu-feng; ZHANG Jie-yu; DU Wei-dong; ZHAI Qi-jie; LI Qiang

    2007-01-01

    Based on the casting manufacture practice of steel slabs by CSP technology, the flow and the temperature fields of the funnel mould and the secondary cooling segment were simulated using the commercial code,CFX4. Compared with other physical investigations, the correlative data of the present simulation results are in good agreement with them. Therefore, a more comprehensive survey for metallurgy characteristic of the flow and the temperature fields in CSP continuous casting process can be achieved.

  11. Comparision of numerical simulation and flow field visualisation using heating foil

    Directory of Open Access Journals (Sweden)

    Matejka Milan

    2012-04-01

    Full Text Available Paper deals with comparison of numerical and experimental solution of the flow field of hump. Synthetic jet actuators were used to influence flow field of the hump. Visualization using heating foil was done and compared with data from numerical simulation. The hump is located in closed measurement area of Eiffel type wind tunnel. Commercial code Fluent was used to perform numerical solution.

  12. An experimental study on the near flow field characteristics of non-circular jets

    Directory of Open Access Journals (Sweden)

    Erdem D.

    2013-04-01

    Full Text Available Subsonic turbulent free jet, issuing from a lobed contoured nozzle in to quiescent air is investigated experimentally. Results are compared with a cir ular jet from a nozzle of the same exit area and same contraction profile. Mean flow characteristics, turbulence intensities and Reynolds shear stresses in the near field region are investigated by using Hot-wire Anemometry. An overall decrease in turbulence intensities and enhanced flow entrainment in the near field of lobed nozzle are observed.

  13. Augment-type two stage accelerator

    International Nuclear Information System (INIS)

    When a flying body accelerated by a gas gun at a first stage enters into an augment rail passing through an introduction tube, an ignition capacitor for initial plasmas is turned ON to apply a voltage between the augment rails. Subsequently, the accelerating gas present behind the flying body is formed into plasmas by a laser, to flow electric current from one of the inner augment rails → plasma armature → the other of the inner augment rails, and additionally accelerate the flying body by Lorentz force formed in this case. Since the plasmas are maintained in a state of higher density than the plasmas obtained by using all of the augment rails, the ignition capacitor for initial plasmas in switched to a power source. As a result, it is possible to flow the maximum current before the plasmas expand, and a large accelerating force and a high magnetic flux density are attained, to improve acceleration performance of the flying body. (N.H.)

  14. Flow field predictions in a model heat exchanger

    Science.gov (United States)

    Theodossiou, V. M.; Sousa, A. C. M.; Carlucci, L. N.

    1988-09-01

    A numerical study of the two-dimensional isothermal steady flow distribution of an incompressible fluid in the shell side of an experimental heat exchanger is described. Computations are performed with and without tubes present in the model, for Reynolds numbers up to 10,000. Baffles and tube bundles are modelled by incorporating the “porous medium” concept into the governing equations. The resulting equations described in primitive variables are solved using a semi-implicit predictor-corrector type scheme. A Multi-Grid technique is employed to solve the linearized pressure correction equation which links momentum and continuity equations. Predictions with the proposed scheme indicate good qualitative agreement when compared with experimental measurements.

  15. Optimization and evaluation of asymmetric flow field-flow fractionation of silver nanoparticles

    DEFF Research Database (Denmark)

    Löschner, Katrin; Navratilova, Jana; Legros, Samuel;

    2013-01-01

    flow rate and spacer height were shown to have a significant influence on the recoveries and retention times of the nanoparticles. Focus time and focus flow rate were optimized with regard to minimum elution of AgNPs in the void volume. The developed method was successfully tested for injected masses......) and calculations of size based on AF(4) theory. Fraction collection followed by transmission electron microscopy was performed to confirm the obtained size distributions and to obtain further information regarding the AgNP shape. Characteristics of the absorbance spectra were used to confirm the presence of non...

  16. Electromagnetic field objects in terms of Balance of Geometric flows

    CERN Document Server

    Donev, Stoil

    2015-01-01

    This paper reviews our physical motivation for choosing appropriate formal presentation of electromagnetic field objects (EMFO). Our view is based on the understanding that EMFO are spatially finite entities carrying internal dynamical structure, so, their available integral time stability should be represented by appropriate adaptation of their internal dynamical structure to corresponding local stress-energy-momentum balance relations with other physical objects. This adaptation process has two aspects: internal and external. Clearly, finding adequate internal dynamical structure giving appropriate integral characteristics of the object, will bring also appropriate behavior of EMFO as a whole. Therefore, the internal local stress-energy-momentum balance among the subsystems of EMFO should formally be presented by appropriately defined tensor-field quantities, which are meant to suggest a dynamical understanding of the abilities of EMFO to successfully communicate with all the rest physical world.

  17. Modeling flow and shear stress fields over unsteady three dimensional dunes

    Science.gov (United States)

    Hardy, Richard; Parsons, Dan; Ashworth, Phil; Reesink, Arjan; Best, Jim

    2014-05-01

    The flow field over dunes has been extensively measured in laboratory conditions and there is general understanding on the nature of the flow over dunes formed under equilibrium flow conditions. This has allowed an understanding of bed shear stress to be derived and the development of morpho-dynamic models. However, fluvial systems typically experience unsteady flow and therefore the sediment-water interface is constantly responding and reorganizing to these unsteady flows and stresses, over a range of both spatial and temporal scales. This is primarily through the adjustment of bed forms (including ripples, dunes and bar forms) which then subsequently alter the flow field. This paper investigates, through the application of a numerical model, the influence of these roughness elements on the overall flow and bed shear stress. A series of physical experiments were undertaken in a flume, 16m long and 2m wide, where a fine sand (D50 of 239µm) was water worked under a range of unsteady hydraulic conditions to generate a series of quasi-equilibrium three dimensional bed forms. During the experiments flow was measured with acoustic Doppler velocimeters, (aDv's). On four occasions the flume was drained and the bed topography measured with terrestrial LiDAR to create digital elevation models. This data provide the necessary boundary conditions and validation data for a numerical three dimensional flow model. The prediction of flow over the four static beds demonstrates the spatial distribution of shear stress and the potential sediment transport paths between the dune crests. These appear to be associated with coherent flow structures formed by localized shear flow. These flow predictions are currently being used to develop a fully three dimensional morphodynamic model to further understand dune dynamics under unsteady flow conditions.

  18. On the magnetic field architecture required to capture superparamagnetic nanoparticles in a microcapillary flow

    International Nuclear Information System (INIS)

    The magnetic field required for the capture of superparamagnetic nanoparticles flowing in a microcapillary array under a constant pressure regime was investigated in vitro. It was found that the nanoparticles were captured in locations that varied significantly in magnetic field strength, and that the location of capture was strongly related to the net volumetric flow through the microcapillary array. A hypothesis is presented to explain these data in which the magnetic field of the trapping Neodymium Iron Boron (NdFeB) block magnet is divided into two zones that act differently on the nanoparticles. In the first 'steering zone', nanoparticles are moved closer to the capillary wall where they can be captured downstream in the second 'capture zone'. This hypothesis can be used in the future to design magnetic field shapes for more effective particle capture at higher flow rates with lower field strengths.

  19. Time-resolved mixing and flow-field measurements during droplet formation in a flow-focusing junction

    Science.gov (United States)

    Carrier, Odile; Gökhan Ergin, F.; Li, Huai-Zhi; Watz, Bo B.; Funfschilling, Denis

    2015-08-01

    Highly monodispersed emulsions can be produced in microfluidic flow-focusing junctions (Anna et al 2003 Appl. Phys. Lett. 82 364-6, Baroud et al 2010 Lab Chip 10 2032-45). This is the reason why many industrial processes in the medical industry among others are based on droplet manipulation and involve at some point a step of dripping within a junction. However, only a few studies have focused on the flow field inside and outside the droplet, even though it is a necessary step for understanding the physical mechanism involved and for modeling the droplet formation process. Water-in-oil emulsions are produced in flow-focusing junctions of square cross sections. The fluids constituting the emulsion are (i) a 5.0 mPa·s silicon oil for the oil phase and (ii) distilled water containing 2.0 wt% of sodium dodecyl sulfate surfactant for the aqueous phase. Time-resolved shadow particle images are acquired using a microscale particle image velocimetry (µPIV) system and flow fields are calculated using an adaptive PIV algorithm in combination with dynamic masking. Inside the microchannel and in the permanent regime, the droplet has an internal circulation that has been well established by Sarrazin et al (AICHE J. 52 4061-70). But during the formation of a droplet in a flow-focusing junction, the flow field is not so well known, and the circulation in the finger flows forward along the sides and returns along the center. The mechanism can be described in terms of four distinct steps: droplet growth, necking, rupture, and recoil. The liquid expelled from the neck just before rupture is also well observed. The flow field and mixing are measured in detail during a complete cycle of formation of a main droplet and satellite droplets using high-speed imaging. This allows us to develop a better understanding of the different forces that are present and of the physical mechanism of droplet formation.

  20. Different elution modes and field programming in gravitational field-flow fractionation IV. Field programming achieved with channels of non-constant cross-sections

    Czech Academy of Sciences Publication Activity Database

    Plocková, Jana; Matulík, František; Chmelík, Josef

    2002-01-01

    Roč. 955, č. 1 (2002), s. 95-103. ISSN 0021-9673 R&D Projects: GA AV ČR IAA4031805 Institutional research plan: CEZ:AV0Z4031919 Keywords : gravitational field-flow fractionation * field programming * hydrodynamic lift forces Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.098, year: 2002

  1. Experimental study of the application of micro-PIV on the flow characteristics detection of micro-gap rotational flow field

    Directory of Open Access Journals (Sweden)

    Fei Tang

    2015-04-01

    Full Text Available For a micro-gap rotational flow field with a large horizontal extent, tiny gap and fast flow velocity, the two-dimensional images shot by the micro-scale Particle ImageVelocimetry(Micro-PIV technique are not sufficient for the study of local or whole flow characteristics. In this paper, by establishing a test bench of a rotational flow field with the functions of driving, positioning, adjustment and sensing, all the local states of the micro-gap rotational flow field can be obtained by horizontally moving the rotating axis to observe point by point. While measuring some local flow fields, two-dimensional pictures are taken by adjusting the focusing height of the objective lens, and then superposed and interpolated according to their shooting order to obtain a quasi-three-dimensional distribution image of the local flow fields, thus obtaining the flow condition of the vertical section of the flow field. The position of the focusing plane and mutual distance are adjusted to realize the measurement of wall shear force in the flow field, providing a feasible reference method for detecting the rheological property of the gap flow field and the effect of surface drag reduction.

  2. Mathematical Model of Blood Flow in Small Blood Vessel in the Presence of Magnetic Field

    Directory of Open Access Journals (Sweden)

    Rekha Bali

    2011-02-01

    Full Text Available A mathematical model for blood flow in the small blood vessel in the presence of magnetic field is presented in this paper. We have modeled the two phase model for the blood flow consists of a central core of suspended erythrocytes and cell-free layer surrounding the core. The system of differential equations has been solved analytically. We have obtained the result for velocity, flow rate and effective viscosity in presence of peripheral layer and magnetic field .All the result has been obtained and discussed through graphs.

  3. Decomposition of the swirling flow field downstream of Francis turbine runner

    Science.gov (United States)

    Rudolf, P.; Štefan, D.

    2012-11-01

    Practical application of proper orthogonal decomposition (POD) is presented. Spatio-temporal behaviour of the coherent vortical structures in the draft tube of hydraulic turbine is studied for two partial load operating points. POD enables to identify the eigen modes, which compose the flow field and rank the modes according to their energy. Swirling flow fields are decomposed, which provides information about their streamwise and crosswise development and the energy transfer among modes. Presented methodology also assigns frequencies to the particular modes, which helps to identify the spectral properties of the flow with concrete mode shapes. Thus POD offers a complementary view to current time domain simulations or measurements.

  4. Solving Incompressible Internal Flow Fields in Turbomachinery with Time Marching Algorithms

    Institute of Scientific and Technical Information of China (English)

    ZhuWei; SuoYisheng; 等

    1999-01-01

    A time marching algorithms,which is used to solve incomprssible internal flow fields in turbomachinery,has been developed.By using Chorin's method of artificial compressibility,the governing equations are transformed from elliptic type into hyperbolic form in order to extend the time marching technique to very low Mach number flows.Viscous effects can be predicted by using the distributed body force method and Baldwin-Lomax eddy viscosity turbulence model.Some accelerating convergence techniques such as multi-grid and local time step method are employed.The application to a flow field within a low-solidity rocket pump inducer is presented and discussed.

  5. Design field controller for level, flow, temperature and networking using YOKOGAWA DCS

    International Nuclear Information System (INIS)

    The application of field controller is an emerging area on most engineering field. The digital field controller has been widely used in the industry since ages ago. In this project, distributed field controller is designed to measure temperature, level and flow of the system used in Industrial Automation using YOKOGAWA DCS network. Here local controller integrated with Distributed Control System by using Yokogawa CENTUM CS 3000. The field controller was designed based on the field plant. Apart from that, a networking was done through Ethernet, which work in dual redundancy

  6. The flow field downstream of a hydraulic jump

    OpenAIRE

    Hornung, Hans G.; Willert, Christian; Turner, Stewart

    1995-01-01

    A control-volume analysis of a hydraulic jump is used to obtain the mean vorticity downstream of the jump as a function of the Froude number. To do this it is necessary to include the conservation of angular momentum. The mean vorticity increases from zero as the cube of Froude number minus one, and, in dimensionless form, approaches a constant at large Froude number. Digital particle imaging velocimetry was applied to travelling hydraulic jumps giving centre-plane velocity field images at a ...

  7. Analysis on MHD Stability of Free Surface Jet flow in a Gradient Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    许增裕; 康伟山; 潘传杰

    2004-01-01

    The simplified modeling for analysis on MHD stability of free surface jet flow in a gradient magnetic fields is based on the theoretical and experimental results on channel liquid metal MHD flow, especially, the results of MHD flow velocity distribution in cross-section of channels (rectangular duct and circular pipe), and the expected results from the modeling are well agreed with the recent experimental data obtained. It is the first modeling which can efficiently explain the experimental results of liquid-metal free surface jet flow.

  8. DIGITAL ANALYSIS TECHNOLOGY FOR MORPHOLOGY OF POLYMER CHAIN COILS IN FLOW FIELDS

    Institute of Scientific and Technical Information of China (English)

    Chi-xing Zhou; Hong Zheng; Wei Yu; Ji-feng Yao; Yu-cheng Li

    2005-01-01

    Polymer chain coils with entanglement is a crucial scale of structures in polymer materials since their relaxation times are matching practical processing times. Based on the phenomenological model of polymer chain coils and a new finite element approach, we have designed a computer software including solver, pre- and post-processing modules, and developed a digital analysis technology for the morphology of polymer chain coils in flow fields (DAMPC). Using this technology we may simulate the morphology development of chain coils in various flow fields, such as simple shear flow, elongational flow,and any complex flow at transient or steady state. The applications made up to now show that the software predictions are comparable with experimental results.

  9. Effects of screens set characteristics on the flow field in a wind tunnel

    Science.gov (United States)

    Santos, A. M.; Souza, D. B.; Costa, F. O.; Farias, M. H.; Massari, P. de L.; Araújo, S.; Zanirath, Y. B.

    2016-07-01

    Wind tunnels have broad range of applications, and although there are common elements among the different types of tunnels, the layout and configuration of each facility will depend on its particular purpose. The flow conditioners section is a common component for all tunnels, and frequently contains flow straighteners and screens [1]. The role of screens is to minimize non uniformities or turbulence level on the flow field. In this work, the development and characteristics of the vertical velocity profile along an atmospheric wind tunnel length were evaluated. By using such data as initial reference, the effects, on the flow, when screens set is inserted on it were analyzed, in order to identify which changes could be done in the wind tunnel configuration to improve the characteristics of the flow field. Such atmospheric wind tunnel is a facility which belongs to the Brazilian National Metrology Institute INMETRO.

  10. Towards an interactive medical system by augmented reality

    Directory of Open Access Journals (Sweden)

    Khawla Ben Abderrahim

    2013-03-01

    Full Text Available Augmented reality is a computer field that progresses rapidly. Its principle is to mix the real world and the virtual world. Many applications already use augmented reality, particularly the medical field. Medical image allows doctors to make diagnosis of the patient. This diagnosis allows him to make the best decision without committing professional mistakes that can cause problems. Hence the idea of integrating augmented reality with medical image analysis to help the doctor to make the best decision. In this paper, we give an overview of our bibliographic study about augmented reality: the definitions and some examples of new augmented reality systems applied in medicine. Thus, we describe basic elements to create an interactive system of augmented reality without markers.

  11. Augmenting computer networks

    Science.gov (United States)

    Bokhari, S. H.; Raza, A. D.

    1984-01-01

    Three methods of augmenting computer networks by adding at most one link per processor are discussed: (1) A tree of N nodes may be augmented such that the resulting graph has diameter no greater than 4log sub 2((N+2)/3)-2. Thi O(N(3)) algorithm can be applied to any spanning tree of a connected graph to reduce the diameter of that graph to O(log N); (2) Given a binary tree T and a chain C of N nodes each, C may be augmented to produce C so that T is a subgraph of C. This algorithm is O(N) and may be used to produce augmented chains or rings that have diameter no greater than 2log sub 2((N+2)/3) and are planar; (3) Any rectangular two-dimensional 4 (8) nearest neighbor array of size N = 2(k) may be augmented so that it can emulate a single step shuffle-exchange network of size N/2 in 3(t) time steps.

  12. Highly conductive composites for fuel cell flow field plates and bipolar plates

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Bor Z; Zhamu, Aruna; Song, Lulu

    2014-10-21

    This invention provides a fuel cell flow field plate or bipolar plate having flow channels on faces of the plate, comprising an electrically conductive polymer composite. The composite is composed of (A) at least 50% by weight of a conductive filler, comprising at least 5% by weight reinforcement fibers, expanded graphite platelets, graphitic nano-fibers, and/or carbon nano-tubes; (B) polymer matrix material at 1 to 49.9% by weight; and (C) a polymer binder at 0.1 to 10% by weight; wherein the sum of the conductive filler weight %, polymer matrix weight % and polymer binder weight % equals 100% and the bulk electrical conductivity of the flow field or bipolar plate is at least 100 S/cm. The invention also provides a continuous process for cost-effective mass production of the conductive composite-based flow field or bipolar plate.

  13. Trajectory of microscale entities in a microdevice for field-flow fractionation based on dielectrophoresis

    Science.gov (United States)

    Mathew, Bobby; Alazzam, Anas; Khashan, Saud A.; El-Khasawneh, Bashar S.

    2015-06-01

    This article deals with the development of a two-dimensional dynamic model for tracking the path of cells subjected to dielectrophoresis, in a continuous flow microfluidic device, for purposes of field-flow fractionation. The nonuniform electric field exists between the top and bottom surface of the microchannel; the top electrode runs over the entire length of the microchannel while the bottom surface of the same holds multiple finite sized electrodes of opposite polarity. The model consists of two governing equations with each describing the movement of the cell in one of the two dimensions of interest. The equations governing of the cell trajectories as well as that of the electric potential inside the microchannel are solved using finite difference method. The model is subsequently used for parametric study; the parameters considered include cell radii, actuation voltage, microchannel height and volumetric flow rate. The model is particularly useful in the design of microfluidic device employing dielectrophoresis for field flow fractionation.

  14. Numerical simulation of mixer-ejector flow field; Mixer ejector nagareba no suchi simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ning, T.; Satofuka, N. [Kyoto Inst. of Technology, Kyoto (Japan)

    1997-06-25

    A three-dimensional explicit time-dependent full Navier-Stokes computation was carried out for a turbulent subsonic mixer-ejector flow field. The objective was to obtain better insight into the complex flow field and to utilize computational fluid dynamics (CFD) to design a mixer ejector with less jet noise while maintaining high thrust and efficiency. The grid consists of about 660000 nodes in two blocks. The numerical simulation shows that the flow field was dominated by a system of large streamwise vortices. These vortices are created at the exit of the mixer nozzle, and they exert a significant influence on the mixing process between primary and secondary flows. Computed velocity, total pressure and total temperature distributions in the exit of the mixer ejector were compared with experimental results. Agreement between computational results and experimental ones is generally good. 9 refs., 15 figs.

  15. Application of Stochastic Unsaturated Flow Theory, Numerical Simulations, and Comparisons to Field Observations

    DEFF Research Database (Denmark)

    Jensen, Karsten Høgh; Mantoglou, Aristotelis

    1992-01-01

    field site in Denmark, where information is available on the spatial variability of soil parameters and variables. Numerical simulations have been carried out, and predictions of the mean behavior and the variance of the capillary tension head and the soil moisture content have been compared to field......A stochastic unsaturated flow theory and a numerical simulation model have been coupled in order to estimate the large-scale mean behavior of an unsaturated flow system in a spatially variable soil. On the basis of the theoretical developments of Mantoglou and Gelhar (1987a, b, c), the theory...... assumes that the local hydraulic soil properties are realizations of three-dimensional random fields, and it derives the large-scale flow structure by averaging the local governing flow equation over the ensemble. The resulting mean model representation is in the form of a partial differential equation...

  16. Changes in mobile phase ion distribution when combining pressurized flow and electric field.

    Science.gov (United States)

    Eriksson, Björn O; Dahl, Magnus; Andersson, Magnus B O; Blomberg, Lars G

    2004-10-01

    The distribution of ions in a capillary with both pressurized flow and an electric field has been studied. We have earlier reported that the overall concentration of ions increase in a capillary with high electric field and a pressurized flow. Now we describe how the ions are distributed in the capillary both along the capillary length and in the radial direction as a result of the parabolic flow profile. We have combined current measurements with finite element techniques in order to get better understanding of the system. We have found that the concentration of the ions that because of the electric mobility moves towards the flow primarily increases at the beginning of the electric field and close to the capillary wall. In view of the results we have proposed an alterative explanation of earlier published results concerning voltage-induced variation in capacity factors. PMID:15472979

  17. A study on impulsive sound attenuation for a high-pressure blast flow field

    International Nuclear Information System (INIS)

    The present work addresses a numerical study on impulsive sound attenuation for a complex high-pressure blast flow field; these characteristics are generated by a supersonic propellant gas flow through a shock tube into an ambient environment. A numerical solver for analyzing the high pressure blast flow field is developed in this study. From numerical simulations, wave dynamic processes (which include a first precursor shock wave, a second main propellant shock wave, and interactions in the muzzle blasts) are simulated and discussed. The pressure variation of the blast flow field is analyzed to evaluate the effect of a silencer. A live firing test is also performed to evaluate four different silencers. The results of this study will be helpful in understanding blast wave and in designing silencers

  18. CFD Prediction of Mean Flow Field and Impeller Capacity for Pitched Blade Turbine

    Institute of Scientific and Technical Information of China (English)

    乔胜超; 王日杰; 杨晓霞; 闫越飞

    2015-01-01

    This work focused on exploring a computational fluid dynamics(CFD)method to predict the macro-mixing characteristics including the mean flow field and impeller capacity for a 45° down-pumping pitched blade tur-bine(PBT)in stirred tanks. Firstly, the three typical mean flow fields were investigated by virtue of three components of liquid velocity. Then the effects of impeller diameter(D)and off-bottom clearance(C)on both the mean flow field and three global macro-mixing parameters concerning impeller capacity were studied in detail. The changes of flow patterns with increasing C/D were predicted from these effects. The simulation results are consistent with the experi-mental results in published literature.

  19. Can Core Flows inferred from Geomagnetic Field Models explain the Earth's Dynamo?

    CERN Document Server

    Schaeffer, Nathanaël; Pais, Maria Alexandra

    2015-01-01

    We test the ability of velocity fields inferred from geomagnetic secular variation data to produce the global magnetic field of the Earth. Our kinematic dynamo calculations use quasi-geostrophic (QG) flows inverted from geomagnetic field models which, as such, incorporate flow structures that are Earth-like and may be important for the geodynamo. Furthermore, the QG hypothesis allows straightforward prolongation of the flow from the core surface to the bulk. As expected from previous studies, we check that a simple quasi-geostrophic flow is not able to sustain the magnetic field against ohmic decay. Additional complexity is then introduced in the flow, inspired by the action of the Lorentz force. Indeed, on centenial timescales, the Lorentz force can balance the Coriolis force and strict quasi-geostrophy may not be the best ansatz. When the columnar flow is modified to account for the action of the Lorentz force, magnetic field is generated for Elsasser numbers larger than 0.25 and magnetic Reynolds numbers l...

  20. Numerical Analysis of Flow Field in Generator End-Winding Region

    Directory of Open Access Journals (Sweden)

    Wei Tong

    2008-01-01

    Full Text Available Cooling in an end-winding region of a high-powered, large-sized generator still remains a challenge today because of a number of factors: a larger number of parts/components with irregular geometries, complexity in cooling flow paths, flow splitting and mixing, and interactions between rotor-induced rotating flows and nonrotating flows from stationary sections. One of the key challenges is to model cooling flows passing through armature bars, which are made up of bundles of strands of insulated copper wires and are bent oppositely to cross each other. This work succeeded in modeling a complex generator end-winding region with great efforts to simplify the model by treating the armature bar region as a porous medium. The flow and pressure fields at the end-winding region were investigated numerically using an axial symmetric computational fluid dynamics (CFD model. Based on the analysis, the cooling flow rate at each flow branch (rotor-stator gap, rotor subslot, outside space block, and small ventilation holes to the heat exchanger was determined, and the high-pressure gradient zones were identified. The CFD results have been successfully used to optimize the flow path configuration for improving the generator operation performance, and the control of the cooling flow, as well as minimizing windage losses and flow-introduced noises.

  1. Comparison of Inflation Processes at the 1859 Mauna Loa Flow, HI, and the McCartys Flow Field, NM

    Science.gov (United States)

    Bleacher, Jacob E.; Garry, W. Brent; Zimbelman, James R.; Crumpler, Larry S.

    2012-01-01

    Basaltic lavas typically form channels or tubes during flow emplacement. However, the importance of sheet flow in the development of basalt ic terrains received recognition over the last 15 years. George Walke r?s research on the 1859 Mauna Loa Flow was published posthumously in 2009. In this paper he discusses the concept of endogenous growth, or inflation, for the distal portion of this otherwise channeldominated lava flow. We used this work as a guide when visiting the 1859 flow to help us better interpret the inflation history of the McCartys flow field in NM. Both well preserved flows display similar clues about the process of inflation. The McCartys lava flow field is among the you ngest (approx.3000 yrs) basaltic lava flows in the continental United States. It was emplaced over slopes of <1 degree, which is similar to the location within the 1859 flow where inflation occurred. Although older than the 1859 flow, the McCartys is located in an arid environ ment and is among the most pristine examples of sheet flow morphologies. At the meter scale the flow surface typically forms smooth, undula ting swales that create a polygonal terrain. The literature for simil ar features includes multiple explanatory hypotheses, original breakouts from adjacent lobes, or inflation related upwarping of crust or sa gging along fractures that enable gas release. It is not clear which of these processes is responsible for polygonal terrains, and it is po ssible that one explanation is not the sole cause of this morphology between all inflated flows. Often, these smooth surfaces within an inflated sheet display lineated surfaces and occasional squeeze-ups alon g swale contacts. We interpret the lineations to preserve original fl ow direction and have begun mapping these orientations to better interpret the emplacement history. At the scale of 10s to 100s of meters t he flow comprises multiple topographic plateaus and depressions. Some depressions display level floors with

  2. Experimental study of the application of micro-PIV on the flow characteristics detection of micro-gap rotational flow field

    OpenAIRE

    Fei Tang; Chunze Wang; Yupeng Shi; Xiaohao Wang

    2015-01-01

    For a micro-gap rotational flow field with a large horizontal extent, tiny gap and fast flow velocity, the two-dimensional images shot by the micro-scale Particle ImageVelocimetry(Micro-PIV) technique are not sufficient for the study of local or whole flow characteristics. In this paper, by establishing a test bench of a rotational flow field with the functions of driving, positioning, adjustment and sensing, all the local states of the micro-gap rotational flow field can be obtained by horiz...

  3. 3D MHD free surface fluid flow simulation based on magnetic-field induction equations

    International Nuclear Information System (INIS)

    The purpose of this paper is to present our recent efforts on 3D MHD model development and our results based on the technique derived from induced-magnetic-field equations. Two important features are utilized in our numerical method to obtain convergent solutions. First, a penalty factor is introduced in order to force the local divergence free condition of the magnetic fields. The second is that we extend the insulating wall thickness to ensure that the induced magnetic field at its boundaries is null. These simulation results for lithium film free surface flows under NSTX outboard mid-plane magnetic field configurations have shown that 3D MHD effects from a surface normal field gradient cause return currents to interact with surface normal fields and produce unfavorable MHD forces. This leads to a substantial change in flow pattern and a reduction in flow velocity, with most of the flow spilling over one side of the chute. These critical phenomena can not be revealed by 2D models. Additionally, a design which overcomes these undesired flow characteristics is obtained

  4. Generation of electromagnetic emission during the injection of dense supersonic plasma flows into arched magnetic field

    Science.gov (United States)

    Mansfeld, Dmitry; Golubev, Sergey; Viktorov, Mikhail; Vodopyanov, Alexander; Yushkov, George

    2015-11-01

    Interaction of dense supersonic plasma flows with an inhomogeneous arched magnetic field is one of the key problems in near-Earth and space plasma physics. In this work a new experimental approach is suggested to study interaction of supersonic (ion Mach number up to 2.7) dense (up to 1015cm-3) plasma flows with inhomogeneous magnetic field (an arched magnetic trap with a field strength up to 3.3 T) which opens wide opportunities to model space plasma processes in laboratory conditions. Fully ionized plasma flows with density from 1013cm-3 to 1015cm-3 are created by plasma generator on the basis of pulsed vacuum arc discharge and injected into open magnetic trap across magnetic field lines. The filling of the arched magnetic trap with plasma and further magnetic field lines break by dense plasma flow was accompanied by pulsed electromagnetic emission at electron cyclotron frequency range, which can generated by electrons in the place of intensive deceleration of plasma flow in magnetic field. Grant of Ministry of Education 14.Z50.31.0007.

  5. Effect of flow field on open channel flow properties using numerical investigation and experimental comparison

    Energy Technology Data Exchange (ETDEWEB)

    Khazaee, I. [Department of Mechanical Engineering, Torbat-e-jam branch, Islamic Azad University, Torbat-e-jam (Iran, Islamic Republic of); Mohammadiun, M. [Department of Mechanical Engineering, Shahrood branch, Islamic Azad University, Shahrood (Iran, Islamic Republic of)

    2012-07-01

    In this paper a complete three-dimensional and two phase CFD model for flow distribution in an open channel investigated. The finite volume method (FVM) with a dynamic Sub grid-scale was carried out for seven cases of different aspect ratios, different inclination angles or slopes and convergence-divergence condition. The volume of fluid (VOF) method was used to allow the free-surface to deform freely with the underlying turbulence. The discharge through open channel flow is often evaluated by velocity-area integration method from the measurement of velocity at discrete locations in the measuring section. The variation of velocity along horizontal and vertical directions is thus very important to decide the location of the sensors. The aspect ratio of the channel, slope of the channel and divergence- convergence of the channel have investigated and the results show that the depth of water at the end of the channel is higher at AR=0.8 against the AR=0.4 and AR=1.2. Also it is clear that by increasing the inclination angle or slope of the channel in case1, case4 and case5 the depth of the water increases. Also it is clear that the outlet mass flow rate is at a minimum value at a range of inclination angle of the channel.

  6. Effect of flow field on open channel flow properties using numerical investigation and experimental comparison

    Directory of Open Access Journals (Sweden)

    I. Khazaee, M. Mohammadiun

    2012-01-01

    Full Text Available In this paper a complete three-dimensional and two phase CFD model for flow distribution in an open channel investigated. The finite volume method (FVM with a dynamic Sub grid-scale was carried out for seven cases of different aspect ratios, different inclination angles or slopes and convergence-divergence condition. The volume of fluid (VOF method was used to allow the free-surface to deform freely with the underlying turbulence. The discharge through open channel flow is often evaluated by velocity-area integration method from the measurement of velocity at discrete locations in the measuring section. The variation of velocity along horizontal and vertical directions is thus very important to decide the location of the sensors. The aspect ratio of the channel, slope of the channel and divergence- convergence of the channel have investigated and the results show that the depth of water at the end of the channel is higher at AR=0.8 against the AR=0.4 and AR=1.2. Also it is clear that by increasing the inclination angle or slope of the channel in case1, case4 and case5 the depth of the water increases. Also it is clear that the outlet mass flow rate is at a minimum value at a range of inclination angle of the channel.

  7. Instantaneous/Simultaneous Flow Field and Endwall Heat Transfer in Turbulent Juncture Flows

    Science.gov (United States)

    Praisner, Thomas; Smith, Charles

    1998-11-01

    A study of the instantaneous and time-mean flow topology along with the associated endwall heat transfer is presented for a turbulent juncture flow formed with an airfoil body. An experimental technique has been employed which allows the recording of simultaneous and instantaneous high-density PIV and thermochromic liquid-crystal based endwall heat transfer data. Data collected on the symmetry, 60o, 90o, and 90o+0.5D planes reveal the existence of a dominant horseshoe vortex, along with a counter-rotating secondary vortex, a co-rotating tertiary vortex, and a small corner vortex on the symmetry plane. Both instantaneous and time mean endwall heat transfer distributions are characterized by two bands of high heat transfer which circumscribe the base of the bluff body. The region upstream of the horseshoe vortex is characterized by a bimodal switching of the near-wall reverse flow which results in quasi-periodic eruptions of the secondary vortex. A physical model for the unsteady interaction process which gives rise to the high levels of endwall heat transfer is presented and discussed.

  8. Field-perpendicular and field-aligned plasma flows observed by EISCAT during a prolonged period of northward IMF

    International Nuclear Information System (INIS)

    The effect of a prolonged period of strongly northward Interplanetary Magnetic Field (IMF) on the high-latitude F-region is studied using data from the EISCAT Common Programme Zero mode of operation on 11-12 August 1982. The analysis of the raw autocorrelation functions is kept to the directly derived parameters Nsub(e), Tsub(e), Tsub(i) and velocity, and limits are defined for the errors introduced by assumptions about ion composition and by changes in the transmitted power and system constant. Simple data-cleaning criteria are employed to eliminate problems due to coherent signals and large background noise levels. The observed variations in plasma densities, temperatures and velocities are interpreted in terms of supporting data from ISEE-3 and local riometers and magnetometers. Both field-aligned and field-perpendicular plasma flows at Tromso showed effects of the northward IMF: convection was slow and irregular and field-aligned flow profiles were characteristic of steady-state polar wind outflow with flux of order 1012 m-2 s-1. This period followed a strongly southward IMF which had triggered a substorm. The substorm gave enhanced convection, with a swing to equatorward flow and large steady-state field-aligned fluxes, leading to the possibility of O+ escape into the magnetosphere. (author)

  9. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    International Nuclear Information System (INIS)

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number. - Highlights: • Heat and mass transfer of nanofluids between parallel plates investigated. • A variable magnetic field is applied on the plates. • Governing equations are solved analytically. • Effects of physical parameters are discussed on the Nusselt number

  10. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    Energy Technology Data Exchange (ETDEWEB)

    Hatami, M., E-mail: m.hatami@tue.nl [Esfarayen University of Technology, Mechanical Engineering Department, Esfarayen, North Khorasan (Iran, Islamic Republic of); Jing, Dengwei; Song, Dongxing [International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi' an 710049 (China); Sheikholeslami, M.; Ganji, D.D. [Department of Mechanical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-12-15

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number. - Highlights: • Heat and mass transfer of nanofluids between parallel plates investigated. • A variable magnetic field is applied on the plates. • Governing equations are solved analytically. • Effects of physical parameters are discussed on the Nusselt number.

  11. Flow in isothermal layers of ferrofluid by action of uniform rotating magnetic field

    International Nuclear Information System (INIS)

    The author attempts to determine how intense the flow of a ferrofluid in a rotating magnetic field can become owing to the temperature dependence of the properties when a nonuniform temperature field has been produced within the volume of such a fluid. It was found that in a channel with a strong temperature dependence of viscosity, a uniform rotating magnetic field is capable of effectively influencing the flow of a ferrofluid within nonisothermal layers, which may be of interest in solving problems of heat transfer

  12. Measurement of pressure distributions and velocity fields of water jet intake flow

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Eun Ho; Yoon, Sang Youl; Kwon, Seong Hoon; Chun, Ho Hwan; Kim, Mun Chan; Kim, Kyung Chun [Busan National Univ., Busan (Korea, Republic of)

    2002-07-01

    Waterjet propulsion system can avoid cavitation problem which is being arised conventional propeller propulsion system. The main issue of designing waterjet system is the boundary layer separation at ramp and lib of water inlet. The flow characteristics are highly depended on Jet to Velocity Ratio(JVR) as well as the intake geometry. The present study is conducted in a wind tunnel to provide accurate pressure destribution at the inlet wall and velocity field of the inlet and exit planes. Particle image velocimetry technique is used to obtain detail velocity fields. Pressure distributions and velocity field are discussed with accelerating and deaccelerating flow zones and the effect of JVR.

  13. Forecasting change of the magnetic field using core surface flows and ensemble Kalman filtering

    OpenAIRE

    Beggan, C.D.; K. A. Whaler

    2009-01-01

    Accurate forecasting of the change of the Earth's internal magnetic field over short intervals of time (e.g., less than five years) has many applications for government, academic and commercial users. Forecasting can be achieved by making a number of reasonable assumptions about how the main field interacts with the flow in the liquid outer core. In particular, the magnetic field can be considered to be entrained in the large scale flow along the core‐mantle boundary surface over short time p...

  14. A critical evaluation of an asymmetrical flow field-flow fractionation system for colloidal size characterization of natural organic matter.

    Science.gov (United States)

    Zhou, Zhengzhen; Guo, Laodong

    2015-06-19

    Colloidal retention characteristics, recovery and size distribution of model macromolecules and natural dissolved organic matter (DOM) were systematically examined using an asymmetrical flow field-flow fractionation (AFlFFF) system under various membrane size cutoffs and carrier solutions. Polystyrene sulfonate (PSS) standards with known molecular weights (MW) were used to determine their permeation and recovery rates by membranes with different nominal MW cutoffs (NMWCO) within the AFlFFF system. Based on a ≥90% recovery rate for PSS standards by the AFlFFF system, the actual NMWCOs were determined to be 1.9 kDa for the 0.3 kDa membrane, 2.7 kDa for the 1 kDa membrane, and 33 kDa for the 10 kDa membrane, respectively. After membrane calibration, natural DOM samples were analyzed with the AFlFFF system to determine their colloidal size distribution and the influence from membrane NMWCOs and carrier solutions. Size partitioning of DOM samples showed a predominant colloidal size fraction in the flow field-flow fractionation technique. In addition, the coupling of AFlFFF with fluorescence EEMs could provide new insights into DOM heterogeneity in different colloidal size fractions. PMID:25958093

  15. Viscous-flow Calculations of Submarine Maneuvering Hydrodynamic Coefficients and Flow Field based on Same Grid Topology

    Directory of Open Access Journals (Sweden)

    Liushuai CAO

    2016-01-01

    Full Text Available To estimate the maneuverability of a submarine at the early design stage, an accurate evaluation of the hydrodynamic coefficients is important. In a collaborative exercise, the authors performed calculations on the bare hull DRAPA SUBOFF submarine to investigate the capability of viscous-flow solvers to predict the forces and moments as well as flow field around the body. A typical simulation program was performed for both the steady drift tests and rotating arm tests. The same grid topology based on multi-block mesh strategy was used to discretize the computational domain. A procedure designated drift sweep was implemented to automatically increment the drift angle during the simulation of steady drift tests. The rotating coordinate system was adopted to perform the simulation of rotating arm tests. The Coriolis force and centrifugal force due to the computation in a rotating frame of reference were treated explicitly and added to momentum equations as source terms. Lastly, the computed forces and moment as a function of angles of drift in both conditions are compared with experimental results and literature values. They always show the correct trend. Flow field quantities including pressure coefficients and vorticity and axial velocity contours are also visualized to vividly describe the evolution of flow motions along the hull.

  16. Investigation of turbulent juncture flow endwall heat transfer and flow field

    Science.gov (United States)

    Praisner, Thomas James

    A study of the instantaneous and time-mean flow topology in a turbulent juncture flow, and the associated endwall heat transfer is presented. A new experimental technique was developed for this work which allows the recording of simultaneous and instantaneous high-density Particle Image Velocimetry (PIV) and thermochromic Liquid-Crystal (LC) based endwall heat transfer data. Endwall heat transfer and simultaneous PIV data in the symmetry, 60sp°, 90sp°, and 90sp° + 0.5D planes were recorded for juncture flows with ResbD\\ ≅ 2.4 × 10sp5. The results illustrate the existence (in an instantaneous and time-mean sense) of a dominant horseshoe vortex, a counter-rotating secondary vortex, a co-rotating tertiary vortex, and a small corner vortex. The corner vortex is a steady feature of the corner region, while the secondary vortex develops sporadically immediately upstream of the horseshoe vortex. The tertiary vortex appears intermittently upstream of the secondary vortex. The region upstream of the horseshoe vortex is characterized by a bimodal switching of the near-wall reverse flow which results in quasi-periodic eruptions of the secondary vortex. The bimodal switching of the reverse flow is shown to be a result of sporadic bursting of the down-wash fluid on the face of the bluff body. Both instantaneous and time mean endwall heat transfer distributions are characterized by two bands of high heat transfer which circumscribe the base of the bluff body. The primary band of high heat transfer (near x/D = 0.05) is a result of the outer-region fluid which impinges on the endwall in the corner region after advecting down the face of the bluff body. The inrush of cool outer-region fluid following the eruptive events upstream of the horseshoe vortex gives rise to the secondary band of high heat transfer near x/D = 0.27. A physical model for the complete interaction process on the symmetry plane is presented along with the associated trends in endwall surface heat transfer

  17. EXPERIMENTAL MEASUREMENT OF MAGNETIC FIELD IN A NOVEL FLOW CONTROL OF MOLD

    Institute of Scientific and Technical Information of China (English)

    G.J. Xu; D.H. Li; J.C. He

    2002-01-01

    In order to know the distribution of magnetic field in a novel flow control of mold(NFC Mold) and to provide the experimental data for the electromagnetic structuredesign and the analysis of flow control in continuous casting mold, the magnetic fieldin a NFC Mold were measured by Tesla meter of Model CT-3. The method of vectorsynthesis was adopted in the measurement of magnetic fields. The results showed thatthe magnetic field in the NFC Mold was composed of two main magnetic areas thatwere symmetrical. Although there was leaking magnetic flux between the lower surfaceof the upper pole and the upper surface of the lower pole on the sides, it was restrainedby the main magnetic fields effectively. Therefore the NFC Mold was more preferablysatisfied to be used in controlling the molten steel flow in continuous casting mold.

  18. Applications of digital holography in visualized measurement of acoustic and flow fields

    Science.gov (United States)

    Zhao, Jianlin; Li, Enpu; Sun, Weiwei; Di, Jianglei

    2010-03-01

    Digital holography allows recording the hologram using digitally imaging devices such as CCD, and reconstructing the holographic image by numerically simulating the diffraction of the hologram. Its main advantages are by which one can directly obtain the complex amplitude distribution of the object field, so that more impersonally measure the detail information of the object field, such as the distribution of the refractive index changing in crystals induced by light irradiation, deformation of the object surface, particle distribution, as well as acoustic field, flow field and temperature distribution in air. In this paper, we summarize the principle and some of our experimental results on the applications of digital holography in visualized measurement of acoustic standing wave (acoustic levitation field), plasma plume and water flow (Karman vortex street) fields.

  19. Augmented reality som wearable

    DEFF Research Database (Denmark)

    Buhl, Mie; Rahn, Annette

    2015-01-01

    Artiklen omhandler design og implementering af Augmented Reality (AR) i form af en wearable i sygeplejerskeuddannelsens anatomiundervisning, mere specifikt undervisning i lungeanatomi og respiration, med fokus på potentialer for visuel læring. Projektet undersøger, hvordan en udviklet AR-applikat......Artiklen omhandler design og implementering af Augmented Reality (AR) i form af en wearable i sygeplejerskeuddannelsens anatomiundervisning, mere specifikt undervisning i lungeanatomi og respiration, med fokus på potentialer for visuel læring. Projektet undersøger, hvordan en udviklet AR...

  20. Accretion onto Stars with Octupole Magnetic Fields: Matter Flow, Hot Spots and Phase Shifts

    CERN Document Server

    Long, Min; Lamb, Frederick K

    2009-01-01

    Recent measurements of the surface magnetic fields of classical T Tauri stars (CTTSs) and magnetic cataclysmic variables show that their magnetic fields have a complex structure. The magnetic field associated with the octupole moment may dominate the magnetic field associated with other moments in some stars, such as the CTTS V2129 Oph. Previously, we studied disc accretion onto stars with magnetic fields described by a superposition of aligned or misaligned dipole and quadrupole moments. In this paper, we present results of the first simulations of disc accretion onto stars with an \\textit {octupole} field. As examples, we consider stars with a superposition of octupole and dipole fields of different strengths and investigate matter flow around them, the shapes of hot spots on their surfaces, and the light curves produced by their rotation. We investigate two possible mechanisms for producing phase shifts in the light curves of stars with complex fields: (1) change of the star's intrinsic magnetic field and ...

  1. Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging

    International Nuclear Information System (INIS)

    The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional projection of the flow along the ultrasound beam. Signals reflected from points further away from the detector will have lower amplitude than signals reflected from points closer to the detector. The effect is very much akin to that modeled by the attenuated Radon transform in emission computed tomography.A least-squares method was adopted to reconstruct a 2D vector field from directional projection measurements. Attenuated projections of only the longitudinal projections of the vector field were simulated. The components of the vector field were reconstructed using the gradient algorithm to minimize a least-squares criterion. This result was compared with the reconstruction of longitudinal projections of the vector field without attenuation. If attenuation is known, the algorithm was able to accurately reconstruct both components of the full vector field from only one set of directional projection measurements. A better reconstruction was obtained with attenuation than without attenuation implying that attenuation provides important information for the reconstruction of flow vector fields.This confirms previous work where we showed that knowledge of the attenuation distribution helps in the reconstruction of MRI diffusion tensor fields from fewer than the required measurements. In the application of ultrasound the attenuation distribution is obtained with pulse wave transmission computed tomography and flow information is obtained with continuous wave Doppler

  2. DiPerna-Lions Flow for Relativistic Particles in an Electromagnetic Field

    Science.gov (United States)

    Jabin, P.-E.; Masmoudi, N.

    2015-09-01

    We show the existence and uniqueness of a DiPerna-Lions flow for relativistic particles subject to a Lorentz force in an electromagnetic field. The electric and magnetic fields solve the linear Maxwell system in the vacuum but for singular initial conditions which are only in the physical energy space. As the corresponding force field is only in L 2, we have to perform a careful analysis of the cancellations over a trajectory.

  3. Flow Field Characteristics of the Rotor Cage in Turbo Air Classifiers

    Institute of Scientific and Technical Information of China (English)

    GUO Lijie; LIU Jiaxiang; LIU Shengzhao

    2009-01-01

    The turbo air classifier is widely used powder classification equipment in a variety of fields. The flow field characteristics of the turbo air classifier are important basis for the improvement of the turbo air classifier's structural design. The flow field characteristics of the rotor cage in turbo air classifiers were investigated under different operating conditions by laser Doppler velocimeter(LDV), and a measure diminishing the axial velocity is proposed. The investigation results show that the tangential velocity of the air flow inside the rotor cage is different from the rotary speed of the rotor cage on the same measurement point due to the influences of both the negative pressure at the exit and the rotation of the rotor cage. The tangential velocity of the air flow likewise decreases as the radius decreases in the case of the rotor cage's low rotary speed. In contrast, the tangential velocity of the air flow increases as the radius decreases in the case of the rotor cage's high rotary speed. Meanwhile, the vortex inside the rotor cage is found to occur near the pressure side of the blade when the rotor cage's rotary speed is less than the tangential velocity of air flow. On the contrary, the vortex is found to occur near the blade suction side once the rotor cage's rotary speed is higher than the tangential velocity of air flow. Inside the rotor cage, the axial velocity could not be disregarded and is largely determined by the distances between the measurement point and the exit.

  4. Effects of a Rotating Aerodynamic Probe on the Flow Field of a Compressor Rotor

    Science.gov (United States)

    Lepicovsky, Jan

    2008-01-01

    An investigation of distortions of the rotor exit flow field caused by an aerodynamic probe mounted in the rotor is described in this paper. A rotor total pressure Kiel probe, mounted on the rotor hub and extending up to the mid-span radius of a rotor blade channel, generates a wake that forms additional flow blockage. Three types of high-response aerodynamic probes were used to investigate the distorted flow field behind the rotor. These probes were: a split-fiber thermo-anemometric probe to measure velocity and flow direction, a total pressure probe, and a disk probe for in-flow static pressure measurement. The signals acquired from these high-response probes were reduced using an ensemble averaging method based on a once per rotor revolution signal. The rotor ensemble averages were combined to construct contour plots for each rotor channel of the rotor tested. In order to quantify the rotor probe effects, the contour plots for each individual rotor blade passage were averaged into a single value. The distribution of these average values along the rotor circumference is a measure of changes in the rotor exit flow field due to the presence of a probe in the rotor. These distributions were generated for axial flow velocity and for static pressure.

  5. Integrating Acoustic Imaging of Flow Regimes With Bathymetry: A Case Study, Main Endeavor Field

    Science.gov (United States)

    Bemis, K. G.; Rona, P. A.; Jackson, D. R.; Jones, C. D.

    2003-12-01

    A unified view of the seafloor and the hydrothermal flow regimes (plumes and diffuse flow) is constructed for three major vent clusters in the Main Endeavour Field (e.g., Grotto, S&M, and Salut) of the Endeavour Segment, Juan de Fuca Ridge. The Main Endeavour Field is one of RIDGE 2000's Integrated Study Sites. A variety of visualization techniques are used to reconstruct the plumes (3D) and the diffuse flow field (2D) based on our acoustic imaging data set (July 2000 cruise). Plumes are identified as volumes of high backscatter intensity (indicating high particulate content or sharp density contrasts due to temperature variations) that remained high intensity when successive acoustic pings were subtracted (indicating that the acoustic targets producing the backscatter were in motion). Areas of diffuse flow are detected using our acoustic scintillation technique (AST). For the Grotto vent region (where a new Doppler technique was used to estimate vertical velocities in the plume), we estimate the areal partitioning between black smoker and diffuse flow in terms of volume fluxes. The volumetric and areal regions, where plume and diffuse flow were imaged, are registered over the bathymetry and compared to geologic maps of each region. The resulting images provide a unified view of the seafloor by integrating hydrothermal flow with geology.

  6. Handling Occlusions for Robust Augmented Reality Systems

    Directory of Open Access Journals (Sweden)

    Maidi Madjid

    2010-01-01

    Full Text Available Abstract In Augmented Reality applications, the human perception is enhanced with computer-generated graphics. These graphics must be exactly registered to real objects in the scene and this requires an effective Augmented Reality system to track the user's viewpoint. In this paper, a robust tracking algorithm based on coded fiducials is presented. Square targets are identified and pose parameters are computed using a hybrid approach based on a direct method combined with the Kalman filter. An important factor for providing a robust Augmented Reality system is the correct handling of targets occlusions by real scene elements. To overcome tracking failure due to occlusions, we extend our method using an optical flow approach to track visible points and maintain virtual graphics overlaying when targets are not identified. Our proposed real-time algorithm is tested with different camera viewpoints under various image conditions and shows to be accurate and robust.

  7. Method of internal 3D flow field numerical simulation for hydrodynamic torque converter

    Institute of Scientific and Technical Information of China (English)

    Tao SHANG; Dingxuan ZHAO; Yuankun ZHANG; Xiangen GUO; Xiangzhong SHI

    2008-01-01

    To enhance the performance of a hydrody-namic torque converter and thoroughly understand the trait of inside flow, a numerical simulation method of internal 3D flow for the three-element centrifugal hydrodynamic torque converter was systematically researched and expatiated in this paper. First, the internal flow field of each impeller was calculated. The curves that illustrate the relationships between the pressure differences of the inlet and outlet versus flux were drawn. Second, the concurrent working point of each impeller was approximately estimated. Finally, a calculation was performed considering the influence on each impeller. The flow field of a working point was solved by multiple calculations and the actual working condition was gradually determined. The pressure and velocity distributions of the flow field were proposed. The performance parameters of the hydrodynamic torque converter were predicted. The calculation method, and the proposed pressure and velocity distribution of the flow field, have practical significance for the design and improvement of a hydrodynamic torque converter.

  8. Simultaneous solution for core magnetic field and fluid flow beneath an electrically conducting mantle

    Science.gov (United States)

    Voorhies, Goerte V.; Nishihama, Masahiro

    1994-01-01

    The effects of laterally homogeneous mantle electrical conductivity have been included in steady, frozen-flux core surface flow estimation along with refinements in method and weighting. The refined method allows simultaneous solution for both the initial radial geomagnetic field component at the core-mantle boundary and the subadjacent fluid motion; it also features Gauss' method for solving the nonlinear inverse problem associated with steady motional induction. The trade-off between spatial complexity of the derived flows and misfit to the weighted Definitive Geomagnetic Reference Field models is studied for various mantle conductivity profiles. For simple flow and a fixed initial geomagnetic condition a fairly high deep-mantle conductivity performs better than either insulating or weakly conducting profiles; however, a thin, very high conductivity layer at the base of the mantle performs almost as well. Simultaneous solution for both initial geomagnetic field and fluid flow reduces the misfit per degree of freedom even more than does changing the mantle conductivity profile. Moreover, when both core field and flow are estimated, the performance of the solutions and the derived flows become insensitive to the conductivity profile.

  9. Augmentation of heat transfer from a solid cylinder wrapped with a porous layer

    DEFF Research Database (Denmark)

    Bhattacharyya, S.; Singh, Ashok

    In the present study, the heat transfer from a porous wrapped solid cylinder is considered. The heated cylinder is placed horizontally and is subjected to a uniform cross-flow. The aim is to investigate the heat transfer augmentation through the inclusion of a porous wrapper. The porous layer is of...... value of porous layer thickness for heat transfer augmentation and its dependence on other properties of the porous foam is obtained. The flow field is analyzed through a single domain approach in which the porous layer is considered as a pseudo-fluid and the composite region as a continuum. A pressure...... correction based iterative algorithm is used for computation. Our results show that a thin porous wrapper of high thermal conductivity can enhance the rate of heat transfer substantially. Periodic vortex shedding is observed from the porous shrouded solid cylinder for high values of Reynolds number. The...

  10. Fractionating power and outlet stream polydispersity in asymmetrical flow field-flow fractionation. Part I: isocratic operation.

    Science.gov (United States)

    Williams, P Stephen

    2016-05-01

    Asymmetrical flow field-flow fractionation (As-FlFFF) has become the most commonly used of the field-flow fractionation techniques. However, because of the interdependence of the channel flow and the cross flow through the accumulation wall, it is the most difficult of the techniques to optimize, particularly for programmed cross flow operation. For the analysis of polydisperse samples, the optimization should ideally be guided by the predicted fractionating power. Many experimentalists, however, neglect fractionating power and rely on light scattering detection simply to confirm apparent selectivity across the breadth of the eluted peak. The size information returned by the light scattering software is assumed to dispense with any reliance on theory to predict retention, and any departure of theoretical predictions from experimental observations is therefore considered of no importance. Separation depends on efficiency as well as selectivity, however, and efficiency can be a strong function of retention. The fractionation of a polydisperse sample by field-flow fractionation never provides a perfectly separated series of monodisperse fractions at the channel outlet. The outlet stream has some residual polydispersity, and it will be shown in this manuscript that the residual polydispersity is inversely related to the fractionating power. Due to the strong dependence of light scattering intensity and its angular distribution on the size of the scattering species, the outlet polydispersity must be minimized if reliable size data are to be obtained from the light scattering detector signal. It is shown that light scattering detection should be used with careful control of fractionating power to obtain optimized analysis of polydisperse samples. Part I is concerned with isocratic operation of As-FlFFF, and part II with programmed operation. Graphical abstract The dash-dotted blue curve describes an assumed log-normal sample molecular weight distribution (right axis

  11. Observations of photospheric magnetic fields and shear flows in flaring active regions

    International Nuclear Information System (INIS)

    Horizontal flows in the photosphere and subsurface convection zone move the footpoints of coronal magnetic field lines. Magnetic energy to power flares can be stored in the corona if the flows drive the fields far from the potential configuration. Videodisk movies were shown with 0.5 to 1 arcsecond resolution of the following simultaneous observations: green continuum, longitudinal magnetogram, Fe I 5576 A line center (mid-photosphere), H alpha wings, and H alpha line center. The movies show a 90 x 90 arcsecond field of view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Magnetic bipoles are emerging over a large area, and the polarities are systematically flowing apart. The horizontal flows were mapped in detail from the continuum movies, and these may be used to predict the future evolution of the region. The horizontal flows are not discernable in H alpha. The H alpha movies strongly suggest reconnection processes in the fibrils joining opposite polarities. When viewed in combination with the magnetic movies, the cause for this evolution is apparent: opposite polarity fields collide and partially cancel, and the fibrils reconnect above the surface. This type of reconnection, driven by subphotospheric flows, complicates the chromospheric and coronal fields, causing visible braiding and twisting of the fibrils. Some of the transient emission events in the fibrils and adjacent plage may also be related

  12. Three-dimensional laryngeal flow fields induced by a model vocal fold polyp

    International Nuclear Information System (INIS)

    Highlights: ► Pathological speech with a unilateral polyp is modeled in a scaled-up flow facility. ► Vortex shedding from the polyp disrupts normal flow behavior. ► Hairpin vortices create spatial velocity asymmetries in the glottal flow. - Abstract: Pathological laryngeal flow fields are investigated in a dynamically-driven, scaled-up model of the vocal folds. Disruption of the flow field due to the presence of a geometric protuberance, representative of a sessile unilateral polyp, is investigated in both the streamwise and transverse flow directions using phase-averaged particle image velocimetry. It is shown that the protuberance disrupts the normal flow behavior of the glottal jet throughout the phonatory cycle. During the divergent portions of the glottal cycle, the flow is characterized by the formation of hairpin vortices downstream of the protuberance. The protuberance also introduces significant velocity gradients in the anterior-posterior direction, which cover ∼30 − 40% of the vocal fold length. It is proposed that the disruption of the normal velocity behavior owing to the presence of a polyp will adversely impact the aerodynamic loadings that drive vocal fold motion, contributing to the temporal and spatial vocal fold asymmetries that are clinically-observed in patients with unilateral polyps.

  13. A case series of flow-through free anterolateral thigh flap to augment the vascularity of ischaemic limbs with soft tissue defect

    Directory of Open Access Journals (Sweden)

    Aditya Aggarwal

    2016-01-01

    Full Text Available Introduction: In a world of fast moving vehicles, heavy machinery and industries crush injury to limbs with vascular compromise and soft tissue defect is common. The traditional treatment is a 2 step one dealing with vascular repair and soft tissue cover separately, in the same operation. We report a series of single step vascular repair and soft tissue cover with flow through anterolateral thigh flap (ALT flap for limb salvage. Materials and Methods: Ten patients with soft tissue defect and vascular injury were included in this study. A two team approach was used to minimise operative time, team one prepared the vessels and team 2 harvested the flap. Observations and Results: Of the ten patients operated (8 males, eight flaps were done for upper limb and two for lower limb salvage. Six anastomosis were done with ulnar vessels, two with radial and two with posterior tibial vessels. Nine extremities could be salvaged while one patient developed progressive thrombosis leading to amputation. Conclusion: The ALT flow-through flap is a versatile single step procedure that can be used to salvage an ischemic limb with soft tissue loss avoiding the need for interpositional vein graft.

  14. Fluid flow in discrete joint sets: Field observations and numerical simulations

    International Nuclear Information System (INIS)

    The distribution of flow within conductive joint sets is influenced by the geometric arrangement of joints and the hydraulic properties of both joints and matrix. We use finite element simulations with an equivalent porous media joint representation to understand the distribution of flow through joints and porous matrix. Isolated joints in a porous media create characteristic flow perturbations in the matrix with reduced fluid potentials near the upstream joint tip, elevated potentials near the downstream tip, and flow shadows adjacent to the joint. In more complex joint systems, flow in any given joint is influenced by its proximity to other joints, resulting in characteristic enhancement or reduction of flow velocities. The permeability ratio (equivalent joint permeability divided by matrix permeability) plays a major role in determining the distribution of flow within complex joint systems. When the permeability ratio is <3.0 orders of magnitude, all joints are indirectly connected to the flow system through the matrix. As joint conductivity increases, flow becomes increasingly localized into directly connected joints. When the permeability ratio exceeds 6.5 orders of magnitude, significant flow occurs only in the directly connected joints. We compare these numerical results with field observations from an ancient reactive flow system now exposed at the Earth's surface. In the field, 32% of joints are associated with chemically altered halos. By explicitly representing mapped joint distributions in numerical simulations, we estimate that 32% of the joints would conduct significant volumes of fluid if joint permeability is 5 orders of magnitude greater than the matrix permeability. This corresponds to an insitu joint aperture of 2.3 mm, closely resembling the 1.8-mm average joint aperture measured on the present-day outcrop. (c) 1999 American Geophysical Union

  15. Magnetohydrodynamic Augmented Propulsion Experiment: I. Performance Analysis and Design

    Science.gov (United States)

    Litchford, R. J.; Cole, J. W.; Lineberry, J. T.; Chapman, J. N.; Schmidt, H. J.; Lineberry, C. W.

    2003-01-01

    The performance of conventional thermal propulsion systems is fundamentally constrained by the specific energy limitations associated with chemical fuels and the thermal limits of available materials. Electromagnetic thrust augmentation represents one intriguing possibility for improving the fuel composition of thermal propulsion systems, thereby increasing overall specific energy characteristics; however, realization of such a system requires an extremely high-energy-density electrical power source as well as an efficient plasma acceleration device. This Technical Publication describes the development of an experimental research facility for investigating the use of cross-field magnetohydrodynamic (MHD) accelerators as a possible thrust augmentation device for thermal propulsion systems. In this experiment,a 1.5-MW(sub e) Aerotherm arc heater is used to drive a 2-MW(sub e) MHD accelerator. The heatsink MHD accelerator is configured as an externally diagonalized, segmented channel, which is inserted into a large-bore, 2-T electromagnet. The performance analysis and engineering design of the flow path are described as well as the parameter measurements and flow diagnostics planned for the initial series of test runs.

  16. Collaborative augmented reality environments

    DEFF Research Database (Denmark)

    Büscher, Monika; Christensen, Michael; Grønbæk, Kaj;

    2000-01-01

    This paper describes Manufaktur, a prototype of a concept and infrastructure that goes beyond the classical CVE systems toward a collaborative augmented reality environment, where users? documents and objects appear as live representations in a 3D workspace. Manufaktur supports collaborative...

  17. Augmented Reality og kulturarv

    DEFF Research Database (Denmark)

    Nielsen, Mikkel Kirkedahl Lysholm

    2013-01-01

    Museerne står overfor at skulle omfavne den digitale kultur i håndteringen af den store mængde viden, institutionerne repræsenterer. Augmented Reality-systemer forbinder ved hjælp af moderne teknologi det virtuelle med det virkelige, og kan derfor synes som en oplagt anvendelsesmulighed i...

  18. Flow and acoustic field due to an inclined plate with a downstream splitter

    Science.gov (United States)

    Kim, C. M.; Conlisk, A. T.

    1993-01-01

    In the present work, the high Reynolds number flow past an inclined plate with a splitter plate placed in its wake is considered numerically. A numerical conformal mapping technique is employed to transform the two-plate system into the same number of cylinders: the flow field is assumed to be two-dimensional. The vortex shedding from the inclined plate is modelled using the discrete vortex method. It is shown that the splitter plate has a profound effect on the development of the flow over a range of values of a suitably defined offset parameter and for a range of positions of the leading edge of the splitter plate. The acoustic field is also calculated and the spectrum reflects the flow results.

  19. Fluid Flow and Solidification Under Combined Action of Magnetic Fields and Microgravity

    Science.gov (United States)

    Li, B. Q.; Shu, Y.; Li, K.; deGroh, H. C.

    2002-01-01

    Mathematical models, both 2-D and 3-D, are developed to represent g-jitter induced fluid flows and their effects on solidification under combined action of magnetic fields and microgravity. The numerical model development is based on the finite element solution of governing equations describing the transient g-jitter driven fluid flows, heat transfer and solutal transport during crystal growth with and without an applied magnetic field in space vehicles. To validate the model predictions, a ground-based g-jitter simulator is developed using the oscillating wall temperatures where timely oscillating fluid flows are measured using a laser PIV system. The measurements are compared well with numerical results obtained from the numerical models. Results show that a combined action derived from magnetic damping and microgravity can be an effective means to control the melt flow and solutal transport in space single crystal growth systems.

  20. Reorienting MHD Colliding Flows: A Shock Physics Mechanism for Generating Filaments Normal to Magnetic Fields

    CERN Document Server

    Fogerty, Erica L; Frank, Adam; Heitsch, Fabian; Pon, Andy

    2016-01-01

    We present numerical simulations of reorienting oblique shocks that form in the collision layer between magnetized colliding flows. Reorientation aligns parsec-scale post-shock filaments normal to the background magnetic field. We find that reorientation begins with pressure gradients between the collision region and the ambient medium. This drives a lateral expansion of post-shock gas, which reorients the growing filament from the outside-in (i.e. from the flow-ambient boundary, toward the colliding flows axis). The final structures of our simulations resemble polarization observations of filaments in Taurus and Serpens South, as well as the integral-shaped filament in Orion A. Given the ubiquity of colliding flows in the interstellar medium, shock reorientation may be relevant to the formation of filaments normal to magnetic fields.

  1. Nonlinear evolution of electron shear flow instabilities in the presence of an external guide magnetic field

    CERN Document Server

    Jain, Neeraj

    2016-01-01

    The dissipation mechanism by which the magnetic field reconnects in the presence of an external (guide) magnetic field in the direction of the main current is not well understood. In thin electron current sheets (ECS) (thickness ~ an electron inertial length) formed in collisionless magnetic reconnection, electron shear flow instabilities (ESFI) are potential candidates for providing an anomalous dissipation mechanism which can break the frozen-in condition of the magnetic field affecting the structure and rate of reconnection. We investigate the evolution of ESFI in guide field magnetic reconnection. The properties of the resulting plasma turbulence and their dependence on the strength of the guide field are studied. Utilizing 3-D electron-magnetohydrodynamic simulations of ECS we show that, unlike the case of ECS self-consistently embedded in anti-parallel magnetic fields, the evolution of thin ECS in the presence of a guide field (equal to the asymptotic value of the reconnecting magnetic field or larger) ...

  2. Solution of Augmented Systems from a Mixed-Hybrid Finite Element Discretization of the Potential Fluid Flow Problem: Asymptotic Rates of Convergence

    Czech Academy of Sciences Publication Activity Database

    Maryška, Jiří; Rozložník, Miroslav; Tůma, Miroslav

    Bratislava : Vydavateĺstvo STU, 2000 - (Handlovičová, A.; Komorníková, M.; Mikula, K.; Ševčovič, D.), s. 100-109 ISBN 80-227-1391-0. [ALGORITMY 2000. Conference on Scientific Computing /15./. Podbanské (SK), 10.09.2000-15.09.2000] R&D Projects: GA ČR GA201/98/P108; GA ČR GA101/00/1035; GA ČR GA201/00/0080 Institutional research plan: AV0Z1030915 Keywords : potential fluid flow problem * mixed-hybrid finite element approximation * symmetric indefinite linear systems * iterative solution * Schur complement system * null-space method * conjugate gradient-type methods * asymptotic rate of convergence Subject RIV: BA - General Mathematics

  3. Dynamic effects on the stretching of the magnetic field by a plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, Manuel [Departamento de Analisis Matematico, Universidad de Valladolid, 47005 Valladolid (Spain)

    2003-08-22

    A key mechanism in the growth of magnetic energy in kinematic dynamos is the stretching of the magnetic field vector by making it point in an unstable direction of the strain matrix. Our objective is to study whether this feature may be maintained in an ideal plasma when also considering the back reaction of the magnetic field upon the flow through the Lorentz force. Several effects occur: in addition to the nonlocal ones exerted by the total pressure, a complex geometry of magnetic field lines decreases the rate of growth of magnetic energy, rotation of the flow enhances it and above all the rate of growth decreases with minus the square of the eigenvalue associated with the magnetic field direction. Thus local dynamics tend to rapidly quench the stretching of the field.

  4. Links between magnetic fields and plasma flows in a coronal hole

    CERN Document Server

    Wiegelmann, T; Marsch, E

    2008-01-01

    We compare the small-scale features visible in the Ne viii Doppler-shift map of an equatorial coronal hole (CH) as observed by SUMER with the small-scale structures of the magnetic field as constructed from a simultaneous photospheric magnetogram by a potential magnetic-field extrapolation. The combined data set is analysed with respect to the small-scale flows of coronal matter, which means that the Ne viii Doppler-shift used as tracer of the plasma flow is investigated in close connection with the ambient magnetic field. Some small closed-field regions in this largely open CH are also found in the coronal volume considered. The Doppler-shift patterns are found to be clearly linked with the field topology.

  5. Cross-field flow of plasma produced by laser resonance photoionization

    International Nuclear Information System (INIS)

    A slow(v≅700m/s) neodymium plasma was produced by laser resonance photoionization in a transverse magnetic field of up to 2240G. The plasma density was in the range of 7.5 x 107 - 1.7 x 109cm-3. The high-density plasma in the low magnetic field flowed straight and was detected by a planar collector set 60mm downstream from the position of plasma production. On the contrary, the low-density plasma did not flow straight across the high magnetic field. The ion numbers detected by the collector decreased and arrival time to the collector delayed. It was found that the ratio of the ions detected by the collector to those produced by laser beams and the arrival times were functions of the plasma relative dielectric constant εr in the wide ranges of plasma density and magnetic field. When εr >1000, the plasma flowed straight across the magnetic field. Therefore it was concluded that the lowest value of εr for the very slow plasma flow in the transverse magnetic field is also consistent with the theoretical prediction εr >(M/m)1/2 =513 for neodymium plasma, where M/m is the mass ratio of the ion to the electron. (author)

  6. Navier-Stokes flow field analysis of compressible flow in a high pressure safety relief valve

    Science.gov (United States)

    Vu, Bruce; Wang, Ten-See; Shih, Ming-Hsin; Soni, Bharat

    1993-12-01

    The objective of this study is to investigate the complex three-dimensional flowfield of an oxygen safety pressure relieve valve during an incident, with a computational fluid dynamic (CFD) analysis. Specifically, the analysis will provide a flow pattern that would lead to the expansion of the eventual erosion pattern of the hardware, so as to combine it with other findings to piece together a most likely scenario for the investigation. The CFD model is a pressure based solver. An adaptive upwind difference scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the velocity-pressure coupling. The computational result indicated vortices formation near the opening of the valve which matched the erosion pattern of the damaged hardware.

  7. Field-Induced Self-Assembled Ferrofluid Aggregation in Pulsatile Flow

    OpenAIRE

    Ganguly, . R.; Zellmer, B.; Puri, Ishwar K.

    2005-01-01

    Ferrofluid aggregation and dispersion occurs at several length scales in pulsatile flow applications, e. g., in ferrofluidic pumps, valves, and biomedical applications such as magnetic drug targeting. Because of a yet limited understanding, ferrohydrodynamic investigations involving laboratory-scale studies in idealized geometries are of considerable use. We have injected a ferrofluid into a pulsatile host flow and produced field-induced dissolution (aggregation) using external magnets. A com...

  8. A Mixing-Layer Flow Noise Analysis by Retarded-time Filtering of the Source Field

    OpenAIRE

    Margnat, Florent

    2010-01-01

    To date, the physical phenomenon that converts kinetic energy into acoustic waves escaping from the flow is not fully understood. Thanks to the increasing computational power, aeroacoustic prediction tools have become more and more fast and accurate. however, it is still challenging to link an acoustic emission pattern to the aerodynamic source field, in terms of causal events. Lighthill's acoustic analogy provides a way to extract the propagative motion from a flow through the expression of ...

  9. Mean Field Theory of Sandpile Avalanches: from the Intermittent to the Continuous Flow Regime

    OpenAIRE

    Benza, V. G.; Nori, Franco; Pla, Oscar

    1993-01-01

    We model the dynamics of avalanches in granular assemblies in partly filled rotating cylinders using a mean-field approach. We show that, upon varying the cylinder angular velocity $\\omega$, the system undergoes a hysteresis cycle between an intermittent and a continuous flow regimes. In the intermittent flow regime, and approaching the transition, the avalanche duration exhibits critical slowing down with a temporal power-law divergence. Upon adding a white noise term, and close to the trans...

  10. COUPLING COMPUTATION OF THE FLOW FIELD AND THE LARGE DEFORMATION OF MEMBRANE STRUCTURE OF STRATOSPHERE AIRSHIPS

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-min

    2008-01-01

    In this article, the mathematical model of the coupling of the three-dimensional fluid flow and the large deformation of membrane structure is established. The fluid-structure coupling interaction is simulated using the computational codes developed by the authors. By analyzing the interactions of membrane and flow field, the aeroelasticity of the airship is detailed. All the results are adopted in the focused study of the stratosphere airship in trimmed state.

  11. Full-field velocity and temperature measurements using magnetic resonance imaging in turbulent complex internal flows

    International Nuclear Information System (INIS)

    Flow and heat transfer in complex internal passages are difficult to predict due to the presence of strong secondary flows and multiple regions of separation. Two methods based on magnetic resonance imaging called 4D magnetic resonance velocimetry (4D-MRV) and thermometry (4D-MRT) are described for measuring the full-field mean velocities and temperatures, respectively, in complex internal passage flows. 4D-MRV measurements are presented for flow through a model of a gas turbine blade internal cooling passage geometry with Reh = 10,000 and compared to PIV measurements in a highly complex 180 deg bend. Measured three-component velocities provide excellent qualitative and quantitative insight into flow structures throughout the entire flow domain. The velocities agree within ±10% in magnitude and ±10 deg in direction in a large portion of the bend which is characterized by turbulent fluctuations as high as 10-20% of the passage inlet bulk velocity. Integrated average flow rates are accurate to 4% throughout the flow domain. Preliminary 4D-MRV/MRT results are presented for heated fully developed turbulent pipe flow at ReD = 13,000

  12. Novel Applications of Magnetic Fields for Fluid Flow Control and for Simulating Variable Gravity Conditions

    Science.gov (United States)

    Ramachandran, N.

    2005-01-01

    Static and dynamic magnetic fields have been used to control convection in many materials processing applications. In most of the applications, convection control (damping or enhancement) is achieved through the Lorentz force that can be tailored to counteract/assist dominant system flows. This technique has been successfully applied to liquids that are electrically conducting, such as high temperature melts of semiconductors, metals and alloys, etc. In liquids with low electrical conductivity such as ionic solutions of salts in water, the Lorentz force is weak and hence not very effective and alternate ways of flow control are necessary. If the salt in solution is paramagnetic then the variation of magnetic susceptibility with temperature and/or concentration can be used for flow control. For thermal buoyancy driven flows this can be accomplished in a temperature range below the Curie point of the salt. The magnetic force is proportional to the magnetic susceptibility and the product of the magnetic field and its gradient. By suitably positioning the experiment cell in the magnet, system flows can be assisted or countered, as desired. A similar approach can be extended to diamagnetic substances and fluids but the required magnetic force is considerably larger than that required for paramagnetic substances. The presentation will provide an overview of work to date on a NASA fluid physics sponsored project that aims to test the hypothesis of convective flow control using strong magnetic fields in protein crystal growth. The objective is to understand the nature of the various forces that come into play, delineate causative factors for fluid flow and to quantify them through experiments, analysis, and numerical modeling. The seminar will report specifically on the experimental results using paramagnetic salts and solutions in magnetic fields and compare them to analytical predictions. Applications of the concept to protein crystallization studies will be discussed

  13. Phase-locked flow field analysis in a synthetic human larynx model

    Science.gov (United States)

    Lodermeyer, Alexander; Becker, Stefan; Döllinger, Michael; Kniesburges, Stefan

    2015-04-01

    The fluid flow within a human larynx plays an essential role in the fluid-structure-acoustic interaction during voice production. This study addresses the flow field downstream of aerodynamically driven, synthetic vocal folds. In order to quantitatively investigate the supraglottal formation of the flow field within one oscillation cycle of the vocal folds, a phase-locked PIV technique is introduced. The pseudo-time-resolved measurement results were averaged for each phase angle. When including a supraglottal channel, the jet was deflected from the centerline of the supraglottal channel and changed the direction of deflection in different cycles. The result is a bistable flow field. Therefore, a sorting method based on the mean cyclic supraglottal pressure difference was introduced. For both states of the flow field, a recirculation area was detected, interacting with the arising glottal jet in every oscillation cycle. This interaction could be identified as the major cause for supraglottal jet deflection, and the sense of rotation of the recirculation area defined the direction of deflection. The asymmetric structure of the flow field was caused by the geometric boundary condition, i.e., due to the present supraglottal channel. An additional key factor was found to be the contact between the two vocal folds in each oscillation cycle which interrupted the jet flow periodically. Removing the supraglottal channel resulted in a symmetric jet location. When avoiding vocal fold contact, the bistable behavior vanished and the jet was steadily deflected to one lateral side. In the present study, it cannot be confirmed that the Coanda effect is responsible for the deflection.

  14. A Comparative Study of the Flow Field of High Viscosity Media in Conventional/Rotary Hydrocyclones

    Institute of Scientific and Technical Information of China (English)

    Ren Liancheng; Liang Zheng; Zhong Gongxiang; Wu Shihui

    2007-01-01

    The flow fields inside conventional and rotary hydrocyclones were simulated respectively. In these simulations,water only and oil-water mixture,with distinctly different viscosities,were used as continuous phases. Simulation results agreed well with the experimental measurements. Simulation results showed that the conventional hydrocyclone could effectively separate sand from water,but could not separate sand from high viscosity water/oil emulsion. This showed that the viscosity of continuous phases influenced greatly both the separation efficiency and the flow field distribution in the conventional hydrocyclone. For high viscosity oil/water sand dispersion (mixture),the rotary hydrocyclone has better separation performance than the conventional one,with a more favorable flow field distribution.

  15. Effect of atomization gas pressure variation on gas flow field in supersonic gas atomization

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, a computational fluid flow model was adopted to investigate the effect of varying atomization gas pressure (P0) on the gas flow field in supersonic gas atomization. The influence of P0 on static pressure and velocity magnitude of the central axis of the flow field was also examined. The numerical results indicate that the maximum gas velocity within the gas field increases with increasing P0. The aspiration pressure (ΔP) is found to decrease as P0 increases at a lower atomization gas pressure. However, at a higher atomization gas pressure increasing P0 causes the opposite: the higher atomization gas pressure, the higher aspiration pressure. The alternation of ΔP is caused by the variations of stagnation point pressure and location of Mach disk, while hardly by the location of stagnation point. A radical pressure gradient is formed along the tip of the delivery tube and increases as P0 increases.

  16. Theoretical background and the flow fields in downhole liquid-liquid hydrocyclone (LLHC

    Directory of Open Access Journals (Sweden)

    Osei Harrison

    2014-07-01

    Full Text Available Hydrocyclone system for downhole oil-water separation provides an effective technique of enhancing the economic viability of higher water-cut wells while at the same time reducing the risk of environmental pollution. This paper describes the hydrodynamics of the liquid-liquid hydrocyclones and the flow fields within it are paramount for achieving successful separation process. Some of the important hydrodynamic flow phenomenon within the liquid-liquid hydrocyclone and how they influence the separation efficiency of water/oil was analyzed through analytical solution. The properties of the liquids were based on Bayan offshore field measured properties. The results indicated that there are two swirling zones separated by stagnant flow field. The inner is the light liquid zone, while the outer is the heavy liquid zone.

  17. NUMERICAL SIMULATION OF FLOW FIELD BETWEEN FRICTIONAL PAIRS IN HYDROVISCOUS DRIVE SURFACE

    Institute of Scientific and Technical Information of China (English)

    HUANG Jiahai; QIU Minxiu; LIAO Lingling; FU Linjian

    2008-01-01

    The flow field of the oil film between frictional pairs in the hydroviscous drive test rig is investigated. A three-dimensional Navier-Stokes(N-S) equation considering viscous force and inertial force rather than Reynolds equation or modified Reynolds equation is presented to model the flow field. Pressure and temperature distribution in radial and circumferential direction under three different conditions, i.e., isothermal, that considering viscosity-temperature characteristic as well as shear thinning non-Newtonian fluid are simulated, respectively, by utilizing the commercial computational fluid dynamics(CFD) software FLUENT. The results reveal that the grooves on the driven plate make the pressure, temperature distribution present periodic variation. The oil temperature and shear rate have important effects on the flow field between frictional pairs, and the oil temperature is more important parameter. The simulation results lay a theoretical foundation for the reasonable designs of hydroviscous drive.

  18. Integral representation of field variables for the finite element solution of viscous flow problems

    Science.gov (United States)

    Wu, J. C.

    1974-01-01

    The kinematics aspects of compressible and incompressible viscous flow problems are recasted into an integral representation for the velocity vector. For the incompressible flow problem, the kinetics aspect is similarly recasted into an integral representation. The result is a system of integral equations ideally suited for the finite element method. The integral representations are shown to permit the confinement of the computation field to the region of nonnegligible vorticity and dilatation which, for the incompressible flow, is identified with the viscous region. This drastic reduction in computation field results in a superior solution speed which is further improved by the use of a flowfield segmentation technique. The new approach is further shown to remove the difficulties associated with previous methods in specifying the far field and extraneous boundary conditions.

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

    Science.gov (United States)

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

    2013-12-01

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

  20. Flow Fields with Vortex in a Small Semi-open Axial Fan

    Institute of Scientific and Technical Information of China (English)

    Norimasa. Shiomi; Yoichi Kinoue; Ying zi Jin; Toshiaki Setoguchi; Kenji Kaneko

    2009-01-01

    In order to clarify the effect of tip clearance (TC) size on fan performance and the flow field at rotor outlet in a small semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was 180mm and test TC sizes were 1 mm (TC=1 mm) and 4mm (TC=4mm). Fan characteristics tests were carried out for two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slant hot-wire probe at four flow-rate conditions. As a result, it was found that the pressure -flow-rate characteristics curves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles along radial measurement stations of TC=4mm largely changed compared with that of TC=1mm in cases of small flow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotor outlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm and TC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm.

  1. Liquid Flow Field on Evaporator of Wiped Short Path Distillation--Experimental Results and Computer Simulation

    Institute of Scientific and Technical Information of China (English)

    XU Songlin; WANG Junwu; XIANG Aishuang; XU Shimin

    2005-01-01

    Short path distillation (SPD) is a kind of high vacuum distillation method, which is suitable for the separation of high boiling, heat sensitivity and viscidity products.In this paper,through measuring the phase-averaged velocity distributions with a conditional sampling method of the particle imaging velocimetry (PIV), the liquid flow field that affects the heat and mass transfer of evaporating thin-film in an SPD evaporator is investigated.Measured results show that the flow velocities decrease rapidly apart from the wiper at different wiper velocities, the maximum velocity appears before wipers, and the quicker the wiping, the larger the flow velocity. Meanwhile, the evaluation of numerical calculations is carried out.The measured velocity distributions indicate clearly the effect of the wiper both on the flow field along its moving direction and on the vortices behind the wiper.Simulation data show that the performance of liquid flow field on the heating surface not only agrees with the experimental results well,but also can give further more information, such as the distribution of turbulent kinetic energy.In this study,turbulent kinetic energy mainly distributes before wipers and laminar flow appears far away from the wipers.

  2. Three-dimensional flow field analysis of the standard fuel assembly for China advanced research reactor

    International Nuclear Information System (INIS)

    Numerical simulation of the flow field of the standard fuel assembly in China Advanced Research Reactor is carried out by using computational fluid dynamics software CFX4.4 and CFX5.5. The flow distribution and pressure difference of different coolant channels in the standard fuel assembly at rated operating condition are reached. Based on the computational pressure drop results of different flow rate, the resistance characteristic curve is given and compared with experimental results. The two results are in good agreement. (authors)

  3. Pose estimation for mobile devices and augmented reality

    NARCIS (Netherlands)

    Caarls, J.

    2009-01-01

    In this thesis we introduce the reader to the field of Augmented Reality (AR) and describe aspects of an AR system. We show the current uses in treatment of phobias, games, sports and industry. We present the challenges for Optical See-Through Augmented Reality in which the real world is perceived n

  4. Study on flow field in capacity regulating actuator for reciprocating compressor

    International Nuclear Information System (INIS)

    The rated capacity of reciprocating compressor tends to be higher than the level needed, so the capacity regulation needs to be implemented to save unnecessary energy waste. Among the methods for reciprocating compressor capacity regulation, holding the suction valves open in partial stroke is a widely used method for its economy, full-range and easy-using characters. The capacity regulation system based on a hydraulic distributor has been successfully applied in industrial process. Hydraulic distributor is the core component of the complete set of stepless capacity regulation system. Continuous high-pressure hydraulic oil provided by hydraulic unit is converted into a pressure impulse wave with a controllable periodic time and pressure acting time when it flows through the hydraulic distributor, which is used to realize the suction valves regulation when it is in the compression stroke. Although the equipment is successfully used in industry fields, the fluid mechanics design of hydraulic distributor is still empirical as its complexity of the fluid field in inner circulation space. For better and more rational distributor design, the flow field in inner zones needs to be better analysed and studied. The manuscript concerned the subjects of path lines, pressure and velocity distribution in hydraulic distributor's flow channels using the CFD software FLUENT. The article explored the flow field characteristics and the flow performance with 5.0 MPa outlet pressure. In the end, a systematic conclusion would be given to guide the actor design

  5. Study on flow field in capacity regulating actuator for reciprocating compressor

    Science.gov (United States)

    Cao, J. L.; Hong, W. R.; Li, Y.; He, Z. K.

    2013-12-01

    The rated capacity of reciprocating compressor tends to be higher than the level needed, so the capacity regulation needs to be implemented to save unnecessary energy waste. Among the methods for reciprocating compressor capacity regulation, holding the suction valves open in partial stroke is a widely used method for its economy, full-range and easy-using characters. The capacity regulation system based on a hydraulic distributor has been successfully applied in industrial process. Hydraulic distributor is the core component of the complete set of stepless capacity regulation system. Continuous high-pressure hydraulic oil provided by hydraulic unit is converted into a pressure impulse wave with a controllable periodic time and pressure acting time when it flows through the hydraulic distributor, which is used to realize the suction valves regulation when it is in the compression stroke. Although the equipment is successfully used in industry fields, the fluid mechanics design of hydraulic distributor is still empirical as its complexity of the fluid field in inner circulation space. For better and more rational distributor design, the flow field in inner zones needs to be better analysed and studied. The manuscript concerned the subjects of path lines, pressure and velocity distribution in hydraulic distributor's flow channels using the CFD software FLUENT. The article explored the flow field characteristics and the flow performance with 5.0 MPa outlet pressure. In the end, a systematic conclusion would be given to guide the actor design.

  6. Assessment of Average Tracer Concentration Approach for Flow Rate Measurement and Field Calibration

    Directory of Open Access Journals (Sweden)

    P. Sidauruk

    2015-12-01

    Full Text Available Tracer method is one of the methods available for open channel flow rate measurements such as in irrigation canals. Average tracer concentration approach is an instantaneous injection method that based on the average tracer concentrations value at the sampling point. If the procedures are correct and scientific considerations are justified, tracer method will give relatively high accuracy of measurements. The accuracy of the average tracer concentration approach has been assessed both in laboratory and field. The results of accuracy tests of open channel flow that has been conducted at the Center for Application Isotopes and Radiation Laboratory-BATAN showed that the accuracy level of average concentrations approach method was higher than 90% compared to the true value (volumetric flow rate. The accuracy of average tracer concentration approach was also assessed during the application of the method to measure flow rate of Mrican irrigation canals as an effort to perform field calibration of existing weirs. Both average tracer concentration approach and weirs can predict the trend of the flow correctly. However, it was observed that flow discrepancies between weirs measurement and average tracer concentration approach predictions were as high as 27%. The discrepancies might be due to the downgrading performances of the weirs because of previous floods and high sediment contents of the flow

  7. Laser Anemometer Measurements of the Flow Field in a 4:1 Pressure Ratio Centrifugal Impeller

    Science.gov (United States)

    Skoch, G. J.; Prahst, P. S.; Wernet, M. P.; Wood, J. R.; Strazisar, A. J.

    1997-01-01

    A laser-doppler anemometer was used to obtain flow-field velocity measurements in a 4:1 pressure ratio, 4.54 kg/s (10 lbm/s), centrifugal impeller, with splitter blades and backsweep, which was configured with a vaneless diffuser. Measured through-flow velocities are reported for ten quasi-orthogonal survey planes at locations ranging from 1% to 99% of main blade chord. Measured through-flow velocities are compared to those predicted by a 3-D viscous steady flow analysis (Dawes) code. The measurements show the development and progression through the impeller and vaneless diffuser of a through-flow velocity deficit which results from the tip clearance flow and accumulation of low momentum fluid centrifuged from the blade and hub surfaces. Flow traces from the CFD analysis show the origin of this deficit which begins to grow in the inlet region of the impeller where it is first detected near the suction surface side of the passage. It then moves toward the pressure side of the channel, due to the movement of tip clearance flow across the impeller passage, where it is cut by the splitter blade leading edge. As blade loading increases toward the rear of the channel the deficit region is driven back toward the suction surface by the cross-passage pressure gradient. There is no evidence of a large wake region that might result from flow separation and the impeller efficiency is relatively high. The flow field in this impeller is quite similar to that documented previously by NASA Lewis in a large low-speed backswept impeller.

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

    International Nuclear Information System (INIS)

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

  9. Plasma flow crisis and limiting electron temperature in a vacuum arc and in axial magnetic field

    International Nuclear Information System (INIS)

    One studied possibility of supersonic motion of cathode plasma in a weak-current vacuum arc placed in axial magnetic field. Increase of electron temperature is shown to result inevitably in reduction of plasma speed up to sonic speed, that is, flow crisis. One derived dependence of the boundary length of plasma stationary flow on magnetic field. The maximum attainable electron temperature of plasma was determined to be governed by ion initial energy and to be equal to the triple value of electron temperature within cathode spot range

  10. NUMERICAL SIMULATION OF 3-D FLOW FIELD IN ARCIFORM PLUNGE POOL

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The 3-D complex turbulent flow fields in aplunge pool with arciform bottom are simulated by using thek-ε model in body-fitted coordinates. The calculated results re-veal the flow characteristics in the arciform plunge pool underthe different flood discharge conditions, which can not be easi-ly obtained in the physical model test because the measure-ment of the complex velocity is very difficult. The calculatedflow fields are helpful to understand in depth the hydrauliccharacteristics of plunge pool. The calculated and the meas-ured pressure distributions on the pool bottom are comparedand in good agreement.

  11. Temperature and flow fields in a high prandtl number liquid bridge under microgravity

    Directory of Open Access Journals (Sweden)

    Yang Shuo

    2015-01-01

    Full Text Available The temperature and flow fields of high prandtl number liquid bridge with surface deformation have been investigated under microgravity by a developed numerical model, and numerical simulations have been carried out based on the Navier-Stokes equations coupled with the energy conservation equation on a staggered grid. In numerical calculations, the free surface deformation and the effects of ambient air are considered. The surface deformation of liquid bridge is monitored by level set method of mass conservation to capture two phase interfaces. Simultaneously, results of temperature and flow fields in liquid bridge are given.

  12. Pressure losses and flow field distortion induced by tip clearance of centrifugal and axial compressors

    Science.gov (United States)

    Senoo, Yasutoshi

    1987-03-01

    The flow field near the tip of compressor rotor blades is distorted by leakage through the tip clearance and the performance of the compressor is deteriorated. The literature regarding the tip clearance of compressor blades consists of computational fluid mechanics and experimental studies on the flow field and the pressure loss. Empirical equations expressing the pressure loss and the efficiency drop are varied. They relate to the lift coefficient in different ways, depending upon the ways of understanding the mechanics of pressure losses. These methods are examined and compared. Also, a brief discussion is made on the optimum value of the tip clearance.

  13. Pressure Distribution Characters of Flow Field around High-Speed Train

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on incompressible viscous fluid Navier-Stokes equation and k-ε 2-equationsturbulent model, an investigation on 3D turbulent flow field around four kinds of train models has been made by finite element method. From the calculation, the pressure distribution characters of flow field around high-speed trains have been obtained. It is significant for strength design of the high-speed train body, for resisting wind design of the facilities beside the high-speed railways and for determining the aerodynamic force of induced air to the human body near the railways.

  14. Sakiadis flow of Maxwell fluid considering magnetic field and convective boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mustafa, M., E-mail: meraj-mm@hotmail.com [School of Natural Sciences (SNS), National University of Sciences and Technology (NUST), Islamabad 44000 (Pakistan); Khan, Junaid Ahmad [Research Centre for Modeling and Simulation (RCMS), National University of Sciences and Technology (NUST), Islamabad 44000 (Pakistan); Hayat, T. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia)

    2015-02-15

    In this paper we address the flow of Maxwell fluid due to constantly moving flat radiative surface with convective condition. The flow is under the influence of non-uniform transverse magnetic field. The velocity and temperature distributions have been evaluated numerically by shooting approach. The solution depends on various interesting parameters including local Deborah number De, magnetic field parameter M, Prandtl number Pr and Biot number Bi. We found that variation in velocity with an increase in local Deborah number De is non-monotonic. However temperature is a decreasing function of local Deborah number De.

  15. Heat transfer in MHD flow due to a linearly stretching sheet with induced magnetic field

    CERN Document Server

    El-Mistikawy, Tarek M A

    2016-01-01

    The full MHD problem of the flow and heat transfer due to a linearly stretching sheet in the presence of a transverse magnetic field is put in a self-similar form. Traditionally ignored physical processes such as induced magnetic field, viscous dissipation, Joule heating, and work shear are included and their importance is established. Cases of prescribed surface temperature, prescribed heat flux, surface feed (injection or suction), velocity slip, and thermal slip are also considered. The problem is shown to admit self similarity. Sample numerical solutions are obtained for chosen combinations of the flow parameters.

  16. Spatial statistics of magnetic field in two-dimensional chaotic flow in the resistive growth stage

    CERN Document Server

    Kolokolov, Igor

    2016-01-01

    The correlation tensors of magnetic field in a two-dimensional chaotic flow of conducting fluid are studied. It is shown that there is a stage of resistive evolution where the field correlators grow exponentially with time what contradicts to the statements present in literature. The two- and four-point field correlation tensors are computed explicitly in this stage in the framework of Batchelor-Kraichnan-Kazantsev model. These tensors demonstrate highly intermittent statistics of the field fluctuations both in space and time.

  17. Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC

    2012-04-05

    We generalize unitarity bounds on operator dimensions in conformal field theory to field theories with spacetime dependent couplings. Below the energy scale of spacetime variation of the couplings, their evolution can strongly affect the physics, effectively shifting the infrared operator scaling and unitarity bounds determined from correlation functions in the theory. We analyze this explicitly for large-N double-trace flows, and connect these to UV complete field theories. One motivating class of examples comes from our previous work on FRW holography, where this effect explains the range of flavors allowed in the dual, time dependent, field theory.

  18. Magnetic field effect on flow parameters of blood along with magnetic particles in a cylindrical tube

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Shashi, E-mail: shashisharma1984@gmail.com; Singh, Uaday; Katiyar, V.K.

    2015-03-01

    In this paper, the effect of external uniform magnetic field on flow parameters of both blood and magnetic particles is reported through a mathematical model using magnetohydrodynamics (MHD) approach. The fluid is acted upon by a varying pressure gradient and an external uniform magnetic field is applied perpendicular to the cylindrical tube. The governing nonlinear partial differential equations were solved numerically and found that flow parameters are affected by the influence of magnetic field. Further, artificial blood (75% water+25% Glycerol) along with iron oxide magnetic particles were prepared and transported into a glass tube with help of a peristaltic pump. The velocity of artificial blood along with magnetic particles was experimentally measured at different magnetic fields ranging from 100 to 600 mT. The model results show that the velocity of blood and magnetic particles is appreciably reduced under the influence of magnetic field, which is supported by our experimental results. - Highlights: • Effect of magnetic field on flow parameters of blood and magnetic particles is studied. • The velocity of blood and magnetic particles is appreciably reduced under a magnetic field. • Experimental results of the velocity of magnetic particles within blood support the mathematical model results.

  19. Study of density field measurement based on NPLS technique in supersonic flow

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Due to the influence of shock wave and turbulence, supersonic density field exhibits strongly inhomogeneous and unsteady characteristics. Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution, limitation of measuring 3D density field, and low signal to noise ratio (SNR). A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field. This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles, which would display the density fluctuation due to the influence of shock waves and vortexes. The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper, and the results reveal shock wave, turbulent boundary layer in the flow with the spatial resolution of 93.2 μm/pixel. By analyzing the results at interval of 5 μs, temporal evolution of density field can be observed.

  20. Study of density field measurement based on NPLS technique in supersonic flow

    Institute of Scientific and Technical Information of China (English)

    TIAN LiFeng; YI ShiHe; ZHAO YuXin; HE Lin; CHENG ZhongYu

    2009-01-01

    Due to the influence of shock wave and turbulence,supersonic density field exhibits strongly inho-mogeneous and unsteady characteristics.Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution,limitation of measuring 3D density field,and low signal to noise ratio (SNR).A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field.This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles,which would display the density fluctuation due to the influence of shock waves and vortexes.The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper,and the results reveal shock wave,turbulent boundary layer in the flow with the spatial resolution of 93.2 pm/pixel.By analyzing the results at interval of 5 μs,temporal evolution of density field can be observed.

  1. Magnetic field effect on flow parameters of blood along with magnetic particles in a cylindrical tube

    International Nuclear Information System (INIS)

    In this paper, the effect of external uniform magnetic field on flow parameters of both blood and magnetic particles is reported through a mathematical model using magnetohydrodynamics (MHD) approach. The fluid is acted upon by a varying pressure gradient and an external uniform magnetic field is applied perpendicular to the cylindrical tube. The governing nonlinear partial differential equations were solved numerically and found that flow parameters are affected by the influence of magnetic field. Further, artificial blood (75% water+25% Glycerol) along with iron oxide magnetic particles were prepared and transported into a glass tube with help of a peristaltic pump. The velocity of artificial blood along with magnetic particles was experimentally measured at different magnetic fields ranging from 100 to 600 mT. The model results show that the velocity of blood and magnetic particles is appreciably reduced under the influence of magnetic field, which is supported by our experimental results. - Highlights: • Effect of magnetic field on flow parameters of blood and magnetic particles is studied. • The velocity of blood and magnetic particles is appreciably reduced under a magnetic field. • Experimental results of the velocity of magnetic particles within blood support the mathematical model results

  2. Electric Field Screening with Back-Flow at Pulsar Polar Cap

    CERN Document Server

    Kisaka, Shota; Terasawa, Toshio

    2016-01-01

    Recent $\\gamma$-ray observations suggest that the particle acceleration occurs at the outer region of the pulsar magnetosphere. The magnetic field lines in the outer acceleration region (OAR) are connected to the neutron star surface (NSS). If copious electron--positron pairs are produced near the NSS, such pairs flow into the OAR and screen the electric field there. To activate the OAR, the electromagnetic cascade due to the electric field near the NSS should be suppressed. However, since a return current is expected along the field lines through the OAR, the outflow extracted from the NSS alone cannot screen the electric field just above the NSS. In this paper, we analytically and numerically study the electric-field screening at the NSS taking into account the effects of the back-flowing particles from the OAR. In certain limited cases, the electric field is screened without significant pair cascade if only ultrarelativistic particles ($\\gamma\\gg1$) flow back to the NSS. On the other hand, if electron--pos...

  3. Flow field velocity measurements for non-isothermal systems. [of chemically reactive flow inside fused silica CVD reactor vessels

    Science.gov (United States)

    Johnson, E. J.; Hyer, P. V.; Culotta, P. W.; Clark, I. O.

    1991-01-01

    Experimental techniques which can be potentially utilized to measure the gas velocity fields in nonisothermal CVD systems both in ground-based and space-based investigations are considered. The advantages and disadvantages of a three-component laser velocimetry (LV) system that was adapted specifically for quantitative determination of the mixed convective flows in a chamber for crystal growth and film formation by CVD are discussed. Data from a horizontal research CVD reactor indicate that current models for the effects of thermophoretic force are not adequate to predict the thermophoretic bias in arbitrary flow configurations. It is concluded that LV techniques are capable of characterizing the fluid dynamics of a CVD reactor at typical growth temperatures. Thermal effects are shown to dominate and stabilize the fluid dynamics of the reactor. Heating of the susceptor increases the gas velocities parallel to the face of a slanted susceptor by up to a factor of five.

  4. Characterization of aquatic humic substances by Flow Field-Flow Fractionation (FFFF) and Gel Permeation Chromatography (GPC): A comparison

    International Nuclear Information System (INIS)

    Aquatic humic substances (HS) of different origin are characterized for their molecular size distribution by the flow field-flow fractionation (FFFF) technique. The results are compared with those obtained by classical gel permeation chromatography (GPC). The influence of different parameters such as eluent composition, crossflow, and type of membrane on the fractionation is investigated. Molecular weight at peak maximum and corresponding weight- and number averaged molecular weights are determined using polystyrenesulphonate calibration standards. Results obtained by FFFF and GPC are comparable, even though the recovery of HS with FFFF is higher. In accordance with the literature, fulvic acids are found to be somewhat smaller than humic acids. Investigated HS samples show molecular weights at peak maximum in the range of 2 to 3 kilodalton. (authors)

  5. Improvement of Separation of Polystyrene Particles with PAN Membranes in Hollow Fiber Flow Field-Flow Fractionation

    International Nuclear Information System (INIS)

    Hollow Fiber flow field-flow fractionation (HF-FlFFF) has been tested in polyacrylonitrile (PAN) membrane channel in order to compare it with polysulfone (PSf) membrane channel. It has been experimentally shown that the separation time of 0.05-0.304 μm polystyrene latex (PSL) standards in PAN membrane channel is shorter than that in PSf channel by approximately 65%. The optimized separation condition in PAN membrane is Vout/ Vrad = 1.4/0.12 mL/min, which is equal to the condition in PSf membrane channel. In addition both the resolution (Rs) and plate height (H) in PAN membrane channel are better than that in PSf membrane channel. The membrane radius was obtained by back calculation with retention time. It shows that the PSf membrane is expanded by swelling and pressure, but the PAN membrane doesn't expand by swelling and pressure

  6. Augmentation Mammaplasty in Asian Women

    OpenAIRE

    Cheng, Ming-Huei; Huang, Jung-Ju

    2009-01-01

    With the rapid economic development of Southeast Asia, the demand for cosmetic surgery has increased rapidly. Breast augmentation is among the most frequently performed cosmetic procedures. However, breast augmentation still has “bad press” in Southeast Asia because of not so distant catastrophes caused by direct liquid silicone injection and “Amazing Gel” augmentations. Asian patients have special characteristics that need to be taken into consideration when performing breast augmentation. T...

  7. Two-phase flow numerical simulation of infiltration and groundwater drainage in a rice field

    Science.gov (United States)

    Lugomela, G. V.

    Farming of rice normally uses a substantially larger amount of water than other cereal grain crops mainly due to the traditional flooding of rice fields. Flooding of the fields result in a seepage flow condition whereby infiltration occurs at a potential rate. The potential infiltration rate obstructs the free movement of pore-air through the ground surface and gradually compresses the pore-air between the infiltrating wetting front and the groundwater table under which subsurface drains are installed. The Galerkin finite element method (FEM) simulation of two-phase flow of air and water in the porous media of the rice field shows that the subsequent increase in the pore-air pressure makes the pore-air act as a link phase which transfers the effects of the processes taking place in the wetting front above and the saturated zone below the groundwater table. This phenomenon is clearly demonstrated when the results of the two-phase flow simulation are compared to the corresponding single-phase flow simulation which neglects the effect of the pore-air. It is concluded that the ‘ponding’ which appears in rice fields can partly be explained by the resistance offered by the pore-air to the percolation process. The study demonstrates that flooding of rice fields during most of its growth time is not necessary rather it is enough to keep the ground surface just saturated and the rest of the water can be saved.

  8. Simulating magnetic nanoparticle behavior in low-field MRI under transverse rotating fields and imposed fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Cantillon-Murphy, P., E-mail: padraig@mit.ed [Division of Gastroenterology, Brigham and Women' s Hospital, Boston, MA (United States); Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA (United States); Wald, L.L., E-mail: wald@nmr.mgh.harvard.ed [MGH-HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States); Adalsteinsson, E., E-mail: elfar@mit.ed [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA (United States); MGH-HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States); Zahn, M., E-mail: zahn@mit.ed [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2010-09-15

    . Analytical predictions and numerical simulations of the transverse rotating magnetic field in the presence of B{sub 0} are investigated to demonstrate the effect of {Omega}, the rotating field frequency, and the magnetic field amplitude on the fluid suspension magnetization. The transverse magnetization due to the rotating transverse field shows strong dependence on the characteristic time constant of the fluid suspension, {tau}. The analysis shows that as the rotating field frequency increases so that {Omega}{tau} approaches unity, the transverse fluid magnetization vector is significantly non-aligned with the applied rotating field and the magnetization's magnitude is a strong function of the field frequency. In this frequency range, the fluid's transverse magnetization is controlled by the applied field which is determined by the operator. The phenomenon, which is due to the physical rotation of the magnetic nanoparticles in the suspension, is demonstrated analytically when the nanoparticles are present in high concentrations (1-3% solid volume fractions) more typical of hyperthermia rather than in clinical imaging applications, and in low MRI field strengths (such as open MRI systems), where the magnetic nanoparticles are not magnetically saturated. The effect of imposed Poiseuille flow in a planar channel geometry and changing nanoparticle concentration is examined. The work represents the first known attempt to analyze the dynamic behavior of magnetic nanoparticles in the MRI environment including the effects of the magnetic nanoparticle spin-velocity. It is shown that the magnitude of the transverse magnetization is a strong function of the rotating transverse field frequency. Interactive fluid magnetization effects are predicted due to non-uniform fluid magnetization in planar Poiseuille flow with high nanoparticle concentrations.

  9. Simulating magnetic nanoparticle behavior in low-field MRI under transverse rotating fields and imposed fluid flow

    International Nuclear Information System (INIS)

    transverse rotating magnetic field in the presence of B0 are investigated to demonstrate the effect of Ω, the rotating field frequency, and the magnetic field amplitude on the fluid suspension magnetization. The transverse magnetization due to the rotating transverse field shows strong dependence on the characteristic time constant of the fluid suspension, τ. The analysis shows that as the rotating field frequency increases so that Ωτ approaches unity, the transverse fluid magnetization vector is significantly non-aligned with the applied rotating field and the magnetization's magnitude is a strong function of the field frequency. In this frequency range, the fluid's transverse magnetization is controlled by the applied field which is determined by the operator. The phenomenon, which is due to the physical rotation of the magnetic nanoparticles in the suspension, is demonstrated analytically when the nanoparticles are present in high concentrations (1-3% solid volume fractions) more typical of hyperthermia rather than in clinical imaging applications, and in low MRI field strengths (such as open MRI systems), where the magnetic nanoparticles are not magnetically saturated. The effect of imposed Poiseuille flow in a planar channel geometry and changing nanoparticle concentration is examined. The work represents the first known attempt to analyze the dynamic behavior of magnetic nanoparticles in the MRI environment including the effects of the magnetic nanoparticle spin-velocity. It is shown that the magnitude of the transverse magnetization is a strong function of the rotating transverse field frequency. Interactive fluid magnetization effects are predicted due to non-uniform fluid magnetization in planar Poiseuille flow with high nanoparticle concentrations.

  10. Turbulent Generation of Flows and Magnetic Field at the Rational Magnetic Surfaces of a Tokamak

    International Nuclear Information System (INIS)

    Full text: Comparative analysis of generation of large-scale structures, zonal flows and streamers, by drift wave turbulence is conducted for periodic systems with magnetic shear such as a tokamak. In a strong magnetic field dynamics of quasi two-dimensional perturbations strongly depends on the value of the wave vector along the magnetic field. When the parallel wave vector is significantly large, so that the parallel phase velocity of perturbation is small compared to electron thermal velocity, the parallel electron motion results in a finite electron density perturbation. It follows the Boltzmann distribution. However, for large-scale structures with poloidal and toroidal symmetry m = n = 0, and the parallel wave vector is zero. This results in strong reduction of density perturbation for m = n = 0. This difference has profound consequences for generation of large-scale zonal flows and streamers due to different structure of the nonlinear interaction matrix. The interaction term has a structure similar to the standard convective nonlinearity for zonal flows, while for streamers it has the structure of the Hasegawa-Mima nonlinearity (which is the higher order due to a small parameter associated with a finite ion Larmor radius). Respectively, zonal flows have the larger growth rate gamma(ZF) compared to that of the streamers. It is shown that 3D electromagnetic helical perturbations will have the growth rate comparable to that of zonal flows if their symmetry coincides with the symmetry of rational magnetic surface, m = nq. The field line bending provides a stabilizing effect and thus determines the radial localization of such structures. Therefore, it is expected that three-dimensional structures of flows and magnetic field will be preferentially generated at the rational magnetic surfaces of a tokamak with a growth rate of order gamma(ZF). This theoretical result may corroborate existing experimental correlations of large-scale shear flow structures with

  11. [The Diagnostics of Detonation Flow External Field Based on Multispectral Absorption Spectroscopy Technology].

    Science.gov (United States)

    Lü, Xiao-jing; Li, Ning; Weng, Chun-sheng

    2016-03-01

    Compared with traditional sampling-based sensing method, absorption spectroscopy technology is well suitable for detonation flow diagnostics, since it can provide with us fast response, nonintrusive, sensitive solution for situ measurements of multiple flow-field parameters. The temperature and concentration test results are the average values along the laser path with traditional absorption spectroscopy technology, while the boundary of detonation flow external field is unknown and it changes all the time during the detonation engine works, traditional absorption spectroscopy technology is no longer suitable for detonation diagnostics. The trend of line strength with temperature varies with different absorption lines. By increasing the number of absorption lines in the test path, more information of the non-uniform flow field can be obtained. In this paper, based on multispectral absorption technology, the reconstructed model of detonation flow external field distribution was established according to the simulation results of space-time conservation element and solution element method, and a diagnostic method of detonation flow external field was given. The model deviation and calculation error of the least squares method adopted were studied by simulation, and the maximum concentration and temperature calculation error was 20.1% and 3.2%, respectively. Four absorption lines of H2O were chosen and detonation flow was scanned at the same time. The detonation external flow testing system was set up for the valveless gas-liquid continuous pulse detonation engine with the diameter of 80 mm. Through scanning H2O absorption lines with a high frequency of 10 kHz, the on-line detection of detonation external flow was realized by direct absorption method combined with time-division multiplexing technology, and the reconstruction of dynamic temperature distribution was realized as well for the first time, both verifying the feasibility of the test method. The test results

  12. Shock tunnel measurements of surface pressures in shock induced separated flow field using MEMS sensor array

    International Nuclear Information System (INIS)

    Characterized not just by high Mach numbers, but also high flow total enthalpies—often accompanied by dissociation and ionization of flowing gas itself—the experimental simulation of hypersonic flows requires impulse facilities like shock tunnels. However, shock tunnel simulation imposes challenges and restrictions on the flow diagnostics, not just because of the possible extreme flow conditions, but also the short run times—typically around 1 ms. The development, calibration and application of fast response MEMS sensors for surface pressure measurements in IISc hypersonic shock tunnel HST-2, with a typical test time of 600 μs, for the complex flow field of strong (impinging) shock boundary layer interaction with separation close to the leading edge, is delineated in this paper. For Mach numbers 5.96 (total enthalpy 1.3 MJ kg−1) and 8.67 (total enthalpy 1.6 MJ kg−1), surface pressures ranging from around 200 Pa to 50 000 Pa, in various regions of the flow field, are measured using the MEMS sensors. The measurements are found to compare well with the measurements using commercial sensors. It was possible to resolve important regions of the flow field involving significant spatial gradients of pressure, with a resolution of 5 data points within 12 mm in each MEMS array, which cannot be achieved with the other commercial sensors. In particular, MEMS sensors enabled the measurement of separation pressure (at Mach 8.67) near the leading edge and the sharply varying pressure in the reattachment zone. (paper)

  13. Instantaneous flow field above the free end of finite-height cylinders and prisms

    International Nuclear Information System (INIS)

    Highlights: • PIV measurements of the flow above the free end of finite-height bodies. • Effect of cross-sectional shape of the models on the instantaneous flow. • Small-scale structures generated by the separated shear layer were revealed. • Effect of aspect ratio on the reattachment of the separated flow on the free end. -- Abstract: The flow above the free ends of surface-mounted finite-height circular cylinders and square prisms was studied experimentally using particle image velocimetry (PIV). Cylinders and prisms with aspect ratios of AR = 9, 7, 5, and 3 were tested at a Reynolds number of Re = 4.2 × 104. The bodies were mounted normal to a ground plane and were partially immersed in a turbulent zero-pressure-gradient boundary layer, where the boundary layer thickness relative to the body width was δ/D = 1.6. PIV measurements were made above the free ends of the bodies in a vertical plane aligned with the flow centreline. The present PIV results provide insight into the effects of aspect ratio and body shape on the instantaneous flow field. The recirculation zone under the separated shear layer is larger for the square prism of AR = 3 compared to the more slender prism of AR = 9. Also, for a square prism with low aspect ratio (AR = 3), the influence of the reverse flow over the free end surface becomes more significant compared to that for a higher aspect ratio (AR = 9). For the circular cylinder, a cross-stream vortex forms within the recirculation zone. As the aspect ratio of the cylinder decreases, the reattachment point of the separated flow on the free end surface moves closer to the trailing edge. For both the square prism and circular cylinder cases, the instantaneous velocity vector field and associated in-plane vorticity field revealed small-scale structures mostly generated by the separated shear layer

  14. Shock tunnel measurements of surface pressures in shock induced separated flow field using MEMS sensor array

    Science.gov (United States)

    Sriram, R.; Ram, S. N.; Hegde, G. M.; Nayak, M. M.; Jagadeesh, G.

    2015-09-01

    Characterized not just by high Mach numbers, but also high flow total enthalpies—often accompanied by dissociation and ionization of flowing gas itself—the experimental simulation of hypersonic flows requires impulse facilities like shock tunnels. However, shock tunnel simulation imposes challenges and restrictions on the flow diagnostics, not just because of the possible extreme flow conditions, but also the short run times—typically around 1 ms. The development, calibration and application of fast response MEMS sensors for surface pressure measurements in IISc hypersonic shock tunnel HST-2, with a typical test time of 600 μs, for the complex flow field of strong (impinging) shock boundary layer interaction with separation close to the leading edge, is delineated in this paper. For Mach numbers 5.96 (total enthalpy 1.3 MJ kg-1) and 8.67 (total enthalpy 1.6 MJ kg-1), surface pressures ranging from around 200 Pa to 50 000 Pa, in various regions of the flow field, are measured using the MEMS sensors. The measurements are found to compare well with the measurements using commercial sensors. It was possible to resolve important regions of the flow field involving significant spatial gradients of pressure, with a resolution of 5 data points within 12 mm in each MEMS array, which cannot be achieved with the other commercial sensors. In particular, MEMS sensors enabled the measurement of separation pressure (at Mach 8.67) near the leading edge and the sharply varying pressure in the reattachment zone.

  15. Magnetic Field Induced Shear Flow in a Strongly Coupled Complex Plasma

    CERN Document Server

    Bandyopadhyay, P; Jiang, K; Morfill, G

    2016-01-01

    We address an experimental observation of shear flow of micron sized dust particles in a strongly coupled complex plasma in presence of a homogeneous magnetic field. Two concentric Aluminum rings of different size are placed on the lower electrode of a radio frequency (rf) parallel plate discharge. The modified local sheath electric field is pointing outward/inward close to the inner/outher ring, respectively. The microparticles, confined by the rings and subject to an ion wind that driven by the local sheath electric field and deflected by an externally applied magnetic field, start flowing in azimuthal direction. Depending upon the rf amplitudes on the electrodes, the dust layers show rotation in opposite direction at the edges of the ring-shaped cloud resulting a strong shear in its center. MD simulations shows a good agreement with the experimental results.

  16. Effect of induced magnetic field on peristaltic flow of a micropolar fluid in an asymmetric channel

    CERN Document Server

    Shit, G C; Ng, E Y K; 10.1002/cnm.1397

    2010-01-01

    Of concern in this paper is an investigation of peristaltic transport of a physiological fluid in an asymmetric channel under long wave length and low-Reynolds number assumptions. The flow is assumed to be incompressible, viscous, electrically conducting micropolar fluid and the effect of induced magnetic field is taken into account. Exact analytical solutions obtained for the axial velocity, microrotation component, stream line pattern, magnetic force function, axial-induced magnetic field as well as the current density distribution across the channel. The flow phenomena for the pumping characteristics, trapping and reflux are also investigated. The results presented reveal that the velocity decreases with the increase of magnetic field as well as the coupling parameter. Moreover, the trapping fluid can be eliminated by the application of an external magnetic field. Thus, the study bears the promise of important applications in physiological systems.

  17. Viscid/inviscid interaction analysis of thrust augmenting ejectors

    Science.gov (United States)

    Bevilacqua, P. M.; Dejoode, A. D.

    1979-01-01

    A method was developed for calculating the static performance of thrust augmenting ejectors by matching a viscous solution for the flow through the ejector to an inviscid solution for the flow outside the ejector. A two dimensional analysis utilizing a turbulence kinetic energy model is used to calculate the rate of entrainment by the jets. Vortex panel methods are then used with the requirement that the ejector shroud must be a streamline of the flow induced by the jets to determine the strength of circulation generated around the shroud. In effect, the ejector shroud is considered to be flying in the velocity field of the jets. The solution is converged by iterating between the rate of entrainment and the strength of the circulation. This approach offers the advantage of including external influences on the flow through the ejector. Comparisons with data are presented for an ejector having a single central nozzle and Coanda jet on the walls. The accuracy of the matched solution is found to be especially sensitive to the jet flap effect of the flow just downstream of the ejector exit.

  18. Time-resolved PIV measurements of the flow field in a stenosed, compliant arterial model

    Science.gov (United States)

    Geoghegan, P. H.; Buchmann, N. A.; Soria, J.; Jermy, M. C.

    2013-05-01

    Compliant (flexible) structures play an important role in several biological flows including the lungs, heart and arteries. Coronary heart disease is caused by a constriction in the artery due to a build-up of atherosclerotic plaque. This plaque is also of major concern in the carotid artery which supplies blood to the brain. Blood flow within these arteries is strongly influenced by the movement of the wall. To study these problems experimentally in vitro, especially using flow visualisation techniques, can be expensive due to the high-intensity and high-repetition rate light sources required. In this work, time-resolved particle image velocimetry using a relatively low-cost light-emitting diode illumination system was applied to the study of a compliant flow phantom representing a stenosed (constricted) carotid artery experiencing a physiologically realistic flow wave. Dynamic similarity between in vivo and in vitro conditions was ensured in phantom construction by matching the distensibility and the elastic wave propagation wavelength and in the fluid system through matching Reynolds ( Re) and Womersley number ( α) with a maximum, minimum and mean Re of 939, 379 and 632, respectively, and a α of 4.54. The stenosis had a symmetric constriction of 50 % by diameter (75 % by area). Once the flow rate reached a critical value, Kelvin-Helmholtz instabilities were observed to occur in the shear layer between the main jet exiting the stenosis and a reverse flow region that occurred at a radial distance of 0.34 D from the axis of symmetry in the region on interest 0-2.5 D longitudinally downstream from the stenosis exit. The instability had an axis-symmetric nature, but as peak flow rate was approached this symmetry breaks down producing instability in the flow field. The characteristics of the vortex train were sensitive not only to the instantaneous flow rate, but also to whether the flow was accelerating or decelerating globally.

  19. Design, fabrication and testing of an air-breathing micro direct methanol fuel cell with compound anode flow field

    International Nuclear Information System (INIS)

    An air-breathing micro direct methanol fuel cell (μDMFC) with a compound anode flow field structure (composed of the parallel flow field and the perforated flow field) is designed, fabricated and tested. To better analyze the effect of the compound anode flow field on the mass transfer of methanol, the compound flow field with different open ratios (ratio of exposure area to total area) and thicknesses of current collectors is modeled and simulated. Micro process technologies are employed to fabricate the end plates and current collectors. The performances of the μDMFC with a compound anode flow field are measured under various operating parameters. Both the modeled and the experimental results show that, comparing the conventional parallel flow field, the compound one can enhance the mass transfer resistance of methanol from the flow field to the anode diffusion layer. The results also indicate that the μDMFC with an anode open ratio of 40% and a thickness of 300 µm has the optimal performance under the 7 M methanol which is three to four times higher than conventional flow fields. Finally, a 2 h stability test of the μDMFC is performed with a methanol concentration of 7 M and a flow velocity of 0.1 ml min−1. The results indicate that the μDMFC can work steadily with high methanol concentration.

  20. Stability of nonaxisymmetric ferrofluid flow in rotating cylinders with magnetic field

    OpenAIRE

    Jitender Singh; Renu Bajaj

    2005-01-01

    Effect of an axially applied magnetic field on the stability of a ferrofluid flow in an annular space between two coaxially rotating cylinders with nonaxisymmetric disturbances has been investigated numerically. The critical value of the ratio Ω∗ of angular speeds of the two cylinders, at the onset of the first nonaxisymmetric mode of disturbance, has been observed to be affected by the applied magnetic field.

  1. Stability of nonaxisymmetric ferrofluid flow in rotating cylinders with magnetic field

    Directory of Open Access Journals (Sweden)

    Jitender Singh

    2005-12-01

    Full Text Available Effect of an axially applied magnetic field on the stability of a ferrofluid flow in an annular space between two coaxially rotating cylinders with nonaxisymmetric disturbances has been investigated numerically. The critical value of the ratio Ω∗ of angular speeds of the two cylinders, at the onset of the first nonaxisymmetric mode of disturbance, has been observed to be affected by the applied magnetic field.

  2. Effect of induced magnetic field on peristaltic flow of a micropolar fluid in an asymmetric channel

    OpenAIRE

    Shit, G. C.; Roy, M.; E. Y. K. Ng

    2010-01-01

    Of concern in this paper is an investigation of peristaltic transport of a physiological fluid in an asymmetric channel under long wave length and low-Reynolds number assumptions. The flow is assumed to be incompressible, viscous, electrically conducting micropolar fluid and the effect of induced magnetic field is taken into account. Exact analytical solutions obtained for the axial velocity, microrotation component, stream line pattern, magnetic force function, axial-induced magnetic field a...

  3. Measurement of flow field and local heat transfer distribution on a scraped heat exchanger crystalliser surface

    OpenAIRE

    Rodriguez, Marcos; Ravelet, Florent; Delfos, Rene; Witkamp, Geert-Jan

    2008-01-01

    In a cylindrical scraped heat exchanger crystallizer geometry the flow field influence on the local heat transfer distribution on an evenly cooled scraped heat exchanger surface has been studied by direct measurements of the heat exchanger surface temperature and the fluid velocity field inside the crystallizer. Liquid Crystal Thermometry revealed that the local heat transfer is higher in the middle area of the scraped surface. Stereoscopic PIV measurements demonstrated that the secondary flo...

  4. Generation of electromagnetic emission during the injection of dense supersonic plasma flows into arched magnetic field

    Science.gov (United States)

    Viktorov, Mikhail; Golubev, Sergey; Mansfeld, Dmitry; Vodopyanov, Alexander

    2016-04-01

    Interaction of dense supersonic plasma flows with an inhomogeneous arched magnetic field is one of the key problems in near-Earth and space plasma physics. It can influence on the energetic electron population formation in magnetosphere of the Earth, movement of plasma flows in magnetospheres of planets, energy release during magnetic reconnection, generation of electromagnetic radiation and particle precipitation during solar flares eruption. Laboratory study of this interaction is of big interest to determine the physical mechanisms of processes in space plasmas and their detailed investigation under reproducible conditions. In this work a new experimental approach is suggested to study interaction of supersonic (ion Mach number up to 2.7) dense (up to 1015 cm‑3) plasma flows with inhomogeneous magnetic field (an arched magnetic trap with a field strength up to 3.3 T) which opens wide opportunities to model space plasma processes in laboratory conditions. Fully ionized plasma flows with density from 1013 cm‑3 to 1015 cm‑3 are created by plasma generator on the basis of pulsed vacuum arc discharge. Then plasma is injected in an arched open magnetic trap along or across magnetic field lines. The filling of the arched magnetic trap with dense plasma and further magnetic field lines break by dense plasma flow were experimentally demonstrated. The process of plasma deceleration during the injection of plasma flow across the magnetic field lines was experimentally demonstrated. Pulsed plasma microwave emission at the electron cyclotron frequency range was observed. It was shown that frequency spectrum of plasma emission is determined by position of deceleration region in the magnetic field of the magnetic arc, and is affected by plasma density. Frequency spectrum shifts to higher frequencies with increasing of arc current (plasma density) because the deceleration region of plasma flow moves into higher magnetic field. The observed emission can be related to the

  5. Augmenting Clozapine With Sertindole

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Emborg, Charlotte; Gydesen, Susanne;

    2012-01-01

    study design was a 12-week, double-blind, randomized, placebo-controlled study including patients with International Statistical Classification of Diseases, 10th Revision schizophrenia (F20.0-F20.3) and treated with clozapine for at least 6 months who had not achieved sufficient response. Patients were...... Inventory, fasting glucose, lipids, and electrocardiogram. Clozapine augmentation with sertindole was not superior to placebo regarding total score or subscale score of the Positive and Negative Syndrome Scale, Clinical Global Impression, World Health Organization Quality of Life Brief, or Drug Attitude...... Inventory. No increased adverse effects compared with placebo were found. Four patients randomized to sertindole experienced a significant worsening of psychosis, and 2 of them required psychiatric admission. Metabolic parameters were unchanged during the study, but augmentation of clozapine with sertindole...

  6. Extraction of skin-friction fields from surface flow visualizations as an inverse problem

    Science.gov (United States)

    Liu, Tianshu

    2013-12-01

    Extraction of high-resolution skin-friction fields from surface flow visualization images as an inverse problem is discussed from a unified perspective. The surface flow visualizations used in this study are luminescent oil-film visualization and heat-transfer and mass-transfer visualizations with temperature- and pressure-sensitive paints (TSPs and PSPs). The theoretical foundations of these global methods are the thin-oil-film equation and the limiting forms of the energy- and mass-transport equations at a wall, which are projected onto the image plane to provide the relationships between a skin-friction field and the relevant quantities measured by using an imaging system. Since these equations can be re-cast in the same mathematical form as the optical flow equation, they can be solved by using the variational method in the image plane to extract relative or normalized skin-friction fields from images. Furthermore, in terms of instrumentation, essentially the same imaging system for measurements of luminescence can be used in these surface flow visualizations. Examples are given to demonstrate the applications of these methods in global skin-friction diagnostics of complex flows.

  7. A wireless flow sensor based on magnetic higher-order harmonic fields

    International Nuclear Information System (INIS)

    The design and fabrication of a wireless, passive flow sensor based on changes in magnetic higher-order harmonic fields is described. The sensor consisted of a flow channel, a permanent magnetic strip (biasing element) and a magnetically soft ferromagnetic strip (sensing element). The biasing element was attached on the channel's wall in parallel to the flow direction, while the sensing element was applied on the opposite wall at a small angle to the flow direction. Flowing water in the channel created a pressure on the sensing element's surface, causing a deflection that varied its separation distance from the biasing element. The change in the separation distance in turn altered the biasing field experienced by the sensing element, causing a shift in its higher-order harmonic fields that could be measured remotely through a magnetic coil. The novelty of this sensor is its wireless, passive nature, which is ideal for applications where wire connections are prohibited. In addition, this sensor can be used on a disposable basis due to its simple design and relatively low material cost

  8. Extraction of skin-friction fields from surface flow visualizations as an inverse problem

    International Nuclear Information System (INIS)

    Extraction of high-resolution skin-friction fields from surface flow visualization images as an inverse problem is discussed from a unified perspective. The surface flow visualizations used in this study are luminescent oil-film visualization and heat-transfer and mass-transfer visualizations with temperature- and pressure-sensitive paints (TSPs and PSPs). The theoretical foundations of these global methods are the thin-oil-film equation and the limiting forms of the energy- and mass-transport equations at a wall, which are projected onto the image plane to provide the relationships between a skin-friction field and the relevant quantities measured by using an imaging system. Since these equations can be re-cast in the same mathematical form as the optical flow equation, they can be solved by using the variational method in the image plane to extract relative or normalized skin-friction fields from images. Furthermore, in terms of instrumentation, essentially the same imaging system for measurements of luminescence can be used in these surface flow visualizations. Examples are given to demonstrate the applications of these methods in global skin-friction diagnostics of complex flows. (paper)

  9. Augmented Reality als Bildungsenhancement?

    OpenAIRE

    Damberger, Thomas

    2015-01-01

    Die Realität, die sich mithilfe von Datenbrillen und Smartphone Applikationen in die virtuelle Welt hinein ausdehnt, erfährt eine Form des Enhancements. Ein solches Enhancement kann unter bestimmten Voraussetzungen als Bildungsenhancement verstanden werden. Der Text befasst sich mit Formen der erweiterten Realität, ferner mit dem, um was es wesentlich bei der Bildung geht und zuletzt mit den Bedingungen, die erforderlich sind, um diesem Wesentlichen mit Hilfe von augmented reality besser zum ...

  10. Experimental observations and modeling of ponding and overland flow in flat, permeable soil fields

    Science.gov (United States)

    Appels, Willemijn; Bogaart, Patrick; van der Zee, Sjoerd

    2015-04-01

    In flat well-drained agricultural terrain, overland flow is a relatively rare phenomenon, yet still a potentially important driver of sediment and nutrient transport. Under these conditions, periods of intense rainfall, shallow groundwater dynamics and local combinations of meso- and microtopography control whether water in ponds will become connected to streams and ditches. Combining overland flow measurements at agricultural fields with a new modeling approach, we explored: (i) what rainfall conditions relate to overland flow and (ii) how does flow route connectivity develop for various types of runoff generation and meso/microtopography? For this purpose, we assessed overland flow at two field sites in flat, lowland catchments in the sandy part of the Netherlands and developed a dynamic model (FAST-runoff) to simulate redistribution of water over a heterogeneous surface with infiltration and soil water storage. Experimentally, it appeared that most overland flow occurred as saturation excess runoff during long wet periods, though infiltration excess runoff generation may have played a role during snowmelt periods that generated small amounts of runoff. For both fields, the contributing area during the saturation excess events was large and flow paths long, irrespective of the profoundly different microtopographies. We explored this behaviour with our FAST-Runoff model and found that under saturation excess conditions, mesotopographic features, such as natural depressions or those caused by tillage, gain importance at the expense of the spatial organization of microtopography. The surface topographies of our experimental fields were equal in terms of standard topographic analytical measures such as Curvature, Convergence Index, and Topographic Wetness Index. However, the fields could be distinguished when analysed with a quantitative indicator of flow for hydrological connectivity. Also, the fields had different dynamics related to the runoff generating mechanism

  11. Nonlinear magnetic field gradients can reduce SAR in flow-driven arterial spin labeling measurements

    Science.gov (United States)

    Marro, Kenneth I.; Lee, Donghoon; Hyyti, Outi M.

    2007-03-01

    This work describes how custom-built gradient coils, designed to generate magnetic fields with amplitudes that vary nonlinearly with position, can be used to reduce the potential for unsafe tissue heating during flow-driven arterial spin labeling processes. A model was developed to allow detailed analysis of the adiabatic excitation process used for flow-driven arterial water stimulation with elimination of tissue signal (FAWSETS) an arterial spin labeling method developed specifically for use in skeletal muscle. The model predicted that, by adjusting the amplitude of the gradient field, the specific absorption rate could be reduced by more than a factor of 6 while still achieving effective labeling. Flow phantom measurements and in vivo measurements from exercising rat hind limb confirmed the accuracy of the model's predictions. The modeling tools were also applied to the more widely used continuous arterial spin labeling (CASL) method and predicted that specially shaped gradients could allow similar reductions in SAR.

  12. Magnetic field and thermal radiation effects on steady hydromagnetic Couette flow through a porous channel

    Directory of Open Access Journals (Sweden)

    Chigozie Israel-Cookey

    2010-09-01

    Full Text Available This paper investigates effects of thermal radiation and magnetic field on hydromagnetic Couette flow of a highly viscous fluid with temperature-dependent viscosity and thermal conductivity at constant pressure through a porous channel. The influence of the channel permeability is also assessed. The relevant governing partial differential equations have been transformed to non-linear coupled ordinary differential equations by virtue of the steady nature of the flow and are solved numerically using a marching finite difference scheme to give approximate solutions for the velocity and temperature profiles. We highlight the effects of Nahme numbers, magnetic field, radiation and permeability parameters on both profiles. The results obtained are used to give graphical illustrations of the distribution of the flow variables and are discussed.

  13. Analysis of Unsteady Transonic Flow Fields by Means of the Colour Streak Schlieren Method

    Directory of Open Access Journals (Sweden)

    J. Ulrych

    2004-01-01

    Full Text Available This article deals with a new approach to the investigation of unsteady transonic flow fields around aerodynamic models and in blade cascades using a schlieren method of flow visualisation. The principle and the application of the Colour Streak Schlieren Method (CSSM are defined. The characteristic flow field features were observed and analysed around an oscillating NACA 0012 airfoil under the conditions of transonic free stream Mach number (M∞ = 0.9, initial angle of attack (α = +4 deg, one amplitude of oscillation (Δα=±3 deg, and three frequencies of model oscillation (f = 1, 15, 30 Hz. There is a description of the terminal shock wave hysteresis across the investigated area, which was revealed in particular cases. Application possibilities of CSSM and its further development are discussed.

  14. Background-oriented schlieren for the study of large flow fields

    Science.gov (United States)

    Trolinger, James D.; Buckner, Ben; L'Esperance, Drew

    2015-09-01

    Modern digital recording and processing techniques combined with new lighting methods and relatively old schlieren visualization methods move flow visualization to a new level, enabling a wide range of new applications and a possible revolution in the visualization of very large flow fields. This paper traces the evolution of schlieren imaging from Robert Hooke, who, in 1665, employed candles and lenses, to modern digital background oriented schlieren (BOS) systems, wherein image processing by computer replaces pure optical image processing. New possibilities and potential applications that could benefit from such a capability are examined. Example applications include viewing the flow field around full sized aircraft, large equipment and vehicles, monitoring explosions on bomb ranges, cooling systems, large structures and even buildings. Objectives of studies include aerodynamics, aero optics, heat transfer, and aero thermal measurements. Relevant digital cameras, light sources, and implementation methods are discussed.

  15. Entropy generation during fluid flow in a channel under the effect of transverse magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Damseh, R.A.; Al-Odat, M.Q. [Al-Huson University College, Al-Balqa Applied University, Mechanical Engineering Department, P.O.B (50), Irbid (Jordan); Al-Nimr, M.A. [Jordan University of Science and Technology, Mechanical Engineering Department, Irbid (Jordan)

    2008-06-15

    Entropy generation due to fluid flow and heat transfer inside a horizontal channel made of two parallel plates under the effect of transverse magnetic field is numerically investigated. The flow is assumed to be steady, laminar, hydro-dynamically and thermally fully developed of electrically conducting fluid. Both horizontal walls are maintained at constant temperatures higher than that of the fluid. The governing equations in Cartesian coordinate are solved by an implicit finite difference technique. After the flow field and the temperature distributions are obtained, the entropy generation profiles are computed and presented graphically. The factors, which were found to affect the problem under consideration are the magnetic parameter, Eckert number, Prandtl number, and the temperature parameter ({theta}{sub {infinity}}). It was found that, entropy generation increased as all parameters involved in the present problem increased. (orig.)

  16. Solving the flow fields in conduits and networks using energy minimization principle with simulated annealing

    CERN Document Server

    Sochi, Taha

    2014-01-01

    In this paper, we propose and test an intuitive assumption that the pressure field in single conduits and networks of interconnected conduits adjusts itself to minimize the total energy consumption required for transporting a specific quantity of fluid. We test this assumption by using linear flow models of Newtonian fluids transported through rigid tubes and networks in conjunction with a simulated annealing (SA) protocol to minimize the total energy cost. All the results confirm our hypothesis as the SA algorithm produces very close results to those obtained from the traditional deterministic methods of identifying the flow fields by solving a set of simultaneous equations based on the conservation principles. The same results apply to electric ohmic conductors and networks of interconnected ohmic conductors. Computational experiments conducted in this regard confirm this extension. Further studies are required to test the energy minimization hypothesis for the non-linear flow systems.

  17. Modelling of the flow field surrounding tidal turbine arrays for varying positions in a channel.

    Science.gov (United States)

    Daly, T; Myers, L E; Bahaj, A S

    2013-02-28

    The modelling of tidal turbines and the hydrodynamic effects of tidal power extraction represents a relatively new challenge in the field of computational fluid dynamics. Many different methods of defining flow and boundary conditions have been postulated and examined to determine how accurately they replicate the many parameters associated with tidal power extraction. This paper outlines the results of numerical modelling analysis carried out to investigate different methods of defining the inflow velocity boundary condition. This work is part of a wider research programme investigating flow effects in tidal turbine arrays. Results of this numerical analysis were benchmarked against previous experimental work conducted at the University of Southampton Chilworth hydraulics laboratory. Results show significant differences between certain methods of defining inflow velocities. However, certain methods do show good correlation with experimental results. This correlation would appear to justify the use of these velocity inflow definition methods in future numerical modelling of the far-field flow effects of tidal turbine arrays. PMID:23319708

  18. Short-range dynamics and prediction of mesoscale flow patterns in the MISTRAL field experiment

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R.O.; Kaufmann, P.; Talkner, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    In a limited area of about 50 km by 50 km with complex topography, wind measurements on a dense network were performed during the MISTRAL field experiment in 1991-1992. From these data the characteristic wind fields were identified by an automated classification method. The dynamics of the resulting twelve typical regional flow patterns is studied. It is discussed how transitions between the flow patterns take place and how well the transition probabilities can be described in the framework of a Markov model. Guided by this discussion, a variety of prediction models were tested which allow a short-term forecast of the flow pattern type. It is found that a prediction model which uses forecast information from the synoptic scale has the best forecast skill. (author) 2 figs., 7 refs.

  19. Numerical simulation on turbulent flow field in convergent-divergent nozzle

    Institute of Scientific and Technical Information of China (English)

    LU Yi-yu; LIO Yong; LI Xiao-hong; FANG Yong; ZHAO Jian-xin

    2009-01-01

    Because of the complication of turbulence's mechanism and law as well as the jet pressure in nozzle is difficult to test by experiment, five turbulent models were applied to numerically simulate the turbulent flow field in convergent-divergent nozzle. Theory analysis and experiment results of mass flow rates conclude that the RNG κ-ε model is the most suitable model. The pressure distribution in the convergent-divergent nozzle was revealed by computational fluid dynamic (CFD) simulating on the turbulent flow field under different pressure conditions. The growing conditions of cavitation bubbles were shown; meanwhile, the phenomena in the experiment could be explained. The differential pressure between the upstream and downstream in nozzle throat section can improve the cavitating effect of cavitation water jet.

  20. Magnetohydrodynamic flow of generalized Maxwell fluids in a rectangular micropump under an AC electric field

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Guangpu [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China); Jian, Yongjun, E-mail: jianyj@imu.edu.cn [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China); Chang, Long [School of Mathematics and Statistics, Inner Mongolia University of Finance and Economics, Hohhot, Inner Mongolia 010051 (China); Buren, Mandula [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China)

    2015-08-01

    By using the method of separation of variables, an analytical solution for the magnetohydrodynamic (MHD) flow of the generalized Maxwell fluids under AC electric field through a two-dimensional rectangular micropump is reduced. By the numerical computation, the variations of velocity profiles with the electrical oscillating Reynolds number Re, the Hartmann number Ha, the dimensionless relaxation time De are studied graphically. Further, the comparison with available experimental data and relevant researches is presented. - Highlights: • MHD flow of the generalized Maxwell fluids under AC electric field is analyzed. • The MHD flow is confined to a two-dimensional rectangular micropump. • Analytical solution is obtained by using the method of separation of variables. • The influences of related parameters on the MHD velocity are discussed.