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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of computational fluids engineering
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Journal DOI :
Korea Society of Computational Fluids Engineering
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Volume & Issues
Volume 18, Issue 4 - Dec 2013
Volume 18, Issue 3 - Sep 2013
Volume 18, Issue 2 - Jun 2013
Volume 18, Issue 1 - Mar 2013
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A FLOW CHARACTERISTICS FOR Y-CONNECTION IN HIGH-REYNOLDS-NUMBER FLOW SYSTEM
Park, Jung Gun ; Park, Jong Ho ; Park, Young Chul ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 1~8
DOI : 10.6112/kscfe.2013.18.2.001
In nuclear power plant, the reactor cooling system has maintained high-Reynolds-number flow above 1E+07 to cool a heat generated by the reactor. To minimize uncertainty for flow calibration, it is necessary to simulate the high Reynolds' number flow. Y-connection is selected to connect four (4) parallel high flow circulation pumps for maintaining the high flow rate. This paper describes the characteristics for Y-connection by computer flow simulation. It was confirmed through the results that the pressure loss of the Y-connection was lower than that of T-connection. Also as the connection angle of Y-connection was small, as the pressure loss was low.
NUMERICAL STUDY OF CHIP COOLING ENHANCEMENT WITH EVAPORATING MIST FLOW
Roh, S.E. ; Kim, D. ; Son, G. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 9~16
DOI : 10.6112/kscfe.2013.18.2.009
The heat transfer enhancement of heat sink with mist flow is studied numerically by solving the conservation equations for mass, momentum and energy in the continuous and dispersed phases. A Lagrangian method is used for tracing dispersed water droplets in the heat sink and an Eulerian species transport model for air and steam mixture. The continuous and dispersed phases are interacted with the drag and evaporation source terms. The computed results show that addition of evaporating mist droplets enhances the cooling performance of heat sink significantly.
STUDY ON BEHAVIOR OF LIQUID NITROGEN IN POROUS MEDIA
Choi, S.W. ; Lee, W.I. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 17~25
DOI : 10.6112/kscfe.2013.18.2.017
The process of flow through porous media is of interest a wide range of engineering fields and areas, and the importance of fluid flow with a change in phase arises from the fact that many industrial processes rely on these phenomena for materials process, energy transfer. Especially, the flow phenomena of cryogenic liquid subjected to evaporation is of interest to investigate how the cryogenic liquid behaves in the porous structure. In this study, thermo physical properties, morphological properties of the glass wool with different bulk densities in terms of its temperature-dependence and permeability behaviors under different applying pressure are discussed. Using the experimentally determined properties, characteristics of two main experimental results are investigated. In addition, simulation results are used to realize the cryogenic liquid's flow in porous media, and are compared with experimental results. By using the experimentally determined properties, more reasonable results can be suggested in dealing with porous media flow.
COMPUTATIONAL ANALYSIS ON DRONE NOISE OF AN AUTOMOBILE WITH OPENED REAR WINDOW
Bai, I.H. ; Moon, Y.J. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 26~34
DOI : 10.6112/kscfe.2013.18.2.026
In modern days, automobiles are the most important means of transportation. With the development of automobiles, noises generated during operation has been recognized as a significant factor of performance to provide drivers with better driving environment along with other passengers. In this study, drone noise(pulsating noise), generated at the rear window when its opened, is predicted to understand the physics of its phenomenon at various velocities. The compressible Navier-stokes equation will be used with
order compact finite difference scheme to analyze the characteristics.
NATURAL CONVECTION BETWEEN TWO HORIZONTAL PLATES WITH SMALL MAGNITUDE NON-UNIFORM TEMPERATURE IN THE LOWER PLATE : Pr=0.7
Yoo, Joo-Sik ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 35~40
DOI : 10.6112/kscfe.2013.18.2.035
Natural convection of air with Pr=0.7 between two horizontal plates with small magnitude non-uniform temperature distribution[
, H : gap width, X : horizontal coordinate] in the lower plate is numerically(
) investigated. In the conduction-dominated regime with
, two upright cells are formed over one wave length(
). For small wave number, the flow becomes unstable with increase of Rayleigh number, and multicellular convection occurs above a critical Rayleigh number. The flow patterns are classified by the number of eddies over one wave length. When
, a transition of
eddy flow occurs with increase of Rayleigh number, and no hysteresis phenomenon is observed. Dual and triple solutions are found for
, and transitions of
eddy flow occur with decrease of Rayleigh number.
A THREE-DIMENSIONAL UNSTRUCTURED FINITE VOLUME METHOD FOR ANALYSIS OF DROPLET IMPINGEMENT IN ICING
Jung, K.Y. ; Jung, S.K. ; Myong, R.S. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 41~48
DOI : 10.6112/kscfe.2013.18.2.041
Ice accretion on the solid surface is an importance factor in assessing the performance of aircraft and wind turbine blade. Changes in the external shape due to ice accretion can greatly deteriorate the aerodynamic performance. In this study, a three-dimensional upwind-type second-order positivity-preserving finite volume CFD scheme based on the unstructured mesh topology is developed to simulate two-phase flow in atmospheric icing condition. The code is then validated by comparing with NASA IRT experimental data on the sphere. The present results of the collection efficiency are found to be in close agreement with experimental data and show improvement near the stagnation region.
EVALUATION OF OPENFAOM IN TERMS OF THE NUMERICAL PRECISION OF INCOMPRESSIBLE FLOW ANALYSIS
Kim, Hyung Min ; Yoon, Dong-Hyeog ; Seul, Kwang-Won ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 49~55
DOI : 10.6112/kscfe.2013.18.2.049
The goal of the research is to evaluate the open source code of OpenFOAM for the use of nuclear plant flow simulation objectively. Of the various incompressible flow solvers, simpleFoam, pimpelFoam are then tested under three validated cases (backward facing step, flow over circular cylinder and turbulent round jet flow). For the evaluation of steady state incompressible laminar flow simulation, low reynolds number of backward facing step flow was solved by simpleFoam. The resultant of the reattached lengths turned out to be similar with the other experimental and simulation results. For transient flow simulation, flow over circular cylinder and turbulent round jet flow were solved by pimpleFoam. The simulation accuracy was evaluated by comparing the resultant flow patterns with the description of the characteristics of the flow over the circular cylinder. The quantitative accuracy was evaluated for no more than 85% by comparing it to the decaying constants of the turbulent round jet velocity.
EFFECTS OF TURBULENCE MODEL AND EDDY VISCOSITY IN SHOCK-WAVE / BOUNDARY LAYER INTERACTION
Jeon, Sang Eon ; Park, Soo Hyung ; Byun, Yung Hwan ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 56~65
DOI : 10.6112/kscfe.2013.18.2.056
Two compression ramp problems and an impinging shock problem are computed to investigate influence of turbulence models and eddy viscosity on the shock-wave / boundary layer interaction. A Navier-Stokes boundary layer generation code was applied to the generation of inflow boundary conditions. Computational results are validated well with the experimental data and effects of turbulence models are investigated. It is shown that the behavior of turbulence (eddy) viscosity directly affects both the extent of the separation and shock-wave positions over the separation.
NUMERICAL INVESTIGATION OF PLUME-INDUCED FLOW SEPARATION FOR A SPACE LAUNCH VEHICLE
Ahn, S.J. ; Hur, N. ; Kwon, O.J. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 66~71
DOI : 10.6112/kscfe.2013.18.2.066
In this paper, the supersonic flows around space launch vehicles have been numerically simulated by using a 3-D RANS flow solver. The focus of the study was made for investigating plume-induced flow separation(PIFS). For this purpose, a vertex-centered finite-volume method was utilized in conjunction with 2nd-order Roe's FDS to discretize the inviscid fluxes. The viscous fluxes were computed based on central differencing. The Spalart-Allmaras model was employed for the closure of turbulence. The Gauss-Seidel iteration was used for time integration. To validate the flow solver, calculation was made for the 0.04 scale model of the Saturn-5 launch vehicle at the supersonic flow condition without exhaust plume, and the predicted results were compared with the experimental data. Good agreements were obtained between the present results and the experiment for the surface pressure coefficient and the Mach number distribution inside the boundary layer. Additional calculations were made for the real scale of the Saturn-5 configuration with exhaust plume. The flow characteristics were analyzed, and the PIFS distances were validated by comparing with the flight data. The KSLV-1 is also simulated at the several altitude conditions. In case of the KSLV-1, PIFS was not observed at all conditions, and it is expected that PIFS is affected by the nozzle position.
DEVELOPMENT OF THE PRE-PROCESSOR FOR CFD
Kim, S.R. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 72~77
DOI : 10.6112/kscfe.2013.18.2.072
The Pre-processor program for CFD is being developed using wxWidgets and OpenGL libraries. This program can be run on both Windows and Linux operating systems. Undergraduate students and beginners can learn and use this very easily by menu and templates. Until now, structured mesh can be created in Cartesian or Cylindrical coordinates. This program will be used easily to make various type of meshes using templates.
NUMERICAL SIMULATIONS OF LOW- AND HIGH-FREQUENCY BUZZ AROUND AN AXISYMMETRIC SUPERSONIC INLET
Kwak, E. ; Lee, N. ; Gong, H. ; Lee, S. ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 78~84
DOI : 10.6112/kscfe.2013.18.2.078
In this paper, numerical simulations of both low- and high-frequency buzz phenomena at the throttle ratios (T.R.) in Nagashima's experiment are performed. The dominant frequencies of the low-and high-frequency buzz in the experiment are about 109 Hz with T.R.=0.97 and 376 Hz with T.R.=0.55, respectively. An axisymmetric solver with the S-A turbulence model is used for the simulations, and DFT(Discrete Fourier Transform) on pressure histories is conducted for the buzz frequency analysis. In the present simulations, the free-stream Mach number and the Reynolds number based on the inlet diameter are 2 and
, respectively. Both the low- and high-frequency buzz phenomena are accomplished without the changes in the grid topology. The dominant frequency of the simulation is about 125 Hz with T.R.=0.97, while it is 399 Hz with T.R.=0.55.
HEAT TRANSFER ENHANCEMENT IN CHANNEL FLOW BY A STREAMWISE-PERIODIC ARRAY OF CIRCULAR CYLINDERS
Jeong, Taekyeong ; Yang, Kyung-Soo ; Lee, Kyongjun ; Kang, Changwoo ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 85~92
DOI : 10.6112/kscfe.2013.18.2.085
In this study, we consider heat transfer enhancement in laminar channel flow by means of an infinite streamwise array of equispaced identical circular cylinders. This flow configuration can be regarded as a model representing a micro channel or an internal heat exchanger with cylindrical vortex generators. A numerical parametric study has been carried out by varying Reynolds number based on the bulk mean velocity and the cylinder diameter, and the gap between the cylinders and the channel wall. An immersed boundary method was employed to facilitate to implement the cylinders on a Cartesian grid system. No-slip condition is employed at all solid boundaries including the cylinders, and the flow is assumed to be periodic in the streamwise direction. Also, the Prandtl number is fixed as 0.7. For thermal boundary conditions on the solid surfaces, it is assumed that heat flux is constant on the channel walls, while the cylinder surfaces remain adiabatic. The presence of the circular cylinders arranged periodically in the streamwise direction causes a significant topological change of the flow, leading to heat transfer enhancement on the channel walls. The Nusselt number averaged on the channel wall is presented for the wide ranges of Reynolds number and the gap. A significant heat transfer enhancement is noticed when the gap is larger than 0.8, while the opposite is the case for smaller gaps. More quantitative results as well as qualitative physical explanations are presented to justify the effectiveness of varying the gap to enhance heat transfer from the channel walls.
VALIDATION OF NUMERICAL APPROACH FOR THE SEDIMENT OF MULTI-SIZE PARTICLES IN A FLUID CONTAINER
Ji, Youngmoo ; Choi, Sangmin ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 93~98
DOI : 10.6112/kscfe.2013.18.2.093
In this paper, we reported the verification of numerical simulation approach for sedimentation of the multi-size particles in a container. The comparison between experimentally measured values and numerically evaluated values on settle down process of fully mixed mixture is carried out. In an attempt to represent the natural particle size distribution, various diameters of single particles are simulated and the results are compared with the outcome of the multi-size computation. When the empirical formula for mean particle size estimation is adopted to define the sediment diameter, computation and comparison are conducted.
VERIFICATION OF TURBULENCE AND NON-DRAG INTERFACIAL FORCE MODELS OF A COMPUTATIONAL MULTI-FLUID DYNAMICS CODE
Park, Ik Kyu ; Chun, Kun Ho ;
Journal of computational fluids engineering, volume 18, issue 2, 2013, Pages 99~108
DOI : 10.6112/kscfe.2013.18.2.099
The standard drag force and virtual mass force, which exert to the primary flow direction, are generally considered in two-phase analysis computational codes. In this paper, the lift force, wall lubrication force, and turbulent dispersion force including turbulence models, which are essential for a computational multi-fluid dynamics model and play an important role in motion perpendicular to the primary flow direction, were introduced and verified with conceptual problems.