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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 16, Issue 4 - Dec 2011
Volume 16, Issue 3 - Sep 2011
Volume 16, Issue 2 - Jun 2011
Volume 16, Issue 1 - Mar 2011
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DEVELOPMENT OF A NUMERICAL SIMULATION METHOD FOR THE ANALYSIS OF SLOSHING PROBLEMS BASED ON CCUP SCHEME
Park, J.C. ; Hwang, S.C. ; Jeong, S.M. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 1~10
DOI : 10.6112/kscfe.2011.16.2.001
A new computational program, which is based on the CIP/CCUP(Constraint Interpolation Profile/CIP Combined Unified Procedure) method, has been developed to numerically analyse sloshing phenomena dealt as multiphase-flow problems. For the convection terms of Navier-Stokes equations, the RCIP(Rational function CIP) method was adopted and the THINC-WLIC(Tangent of Hyperbola for Interface Capturing-Weighted Line Interface Calculation) method was used to capture the air/water interface. To validate the present numerical method, two-dimensional dam-breaking and sloshing problems in a rectangular tank were solved by the developed method in a stationary Cartesian grid system. In the case of sloshing problems, simulations by using a improved MPS(Moving Particle Simulation) method, which is named as PNU-MPS(Pusan National University-MPS), were also carried out. The computational results are compared with those of experiments and most of the comparisons are reasonably good.
ANALYSIS OF HEAT TRANSFER OF INCLINED IMPINGING JETS ON A CONCAVE SURFACE
Heo, M.W. ; Lee, K.D. ; Kim, K.Y. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 11~16
DOI : 10.6112/kscfe.2011.16.2.011
Numerical analyses have been carried out to analyze the three-dimensional turbulent heat transfer by impingement jet on a concave surface with variation of geometric configurations. Three-dimensional Reynolds averaged Navier-stokes equations have been calculated using the shear stress transport turbulent model. The numerical results for heat transfer rate were validated in comparison with the experimental data. The distance between jet nozzles and angle of inclined jet nozzle were selected as the geometric variables. Area-averaged Nusselt numbers on concave surface are evaluated to find the characteristics of heat transfer with the two geometric variables. The heat transfer increases as the distance between jet nozzles increases, and the inclined impinging jets show much better heat transfer performance than the vertical impinging jet.
ANALYSIS OF VORTEX SHEDDING PHENOMENA AROUND PANTOGRAPH PANHEAD FOR TRAIN USING LARGE EDDY SIMULATION
Jang, Yong-Jun ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 17~23
DOI : 10.6112/kscfe.2011.16.2.017
The turbulent flow and vortex shedding phenomena around pantograph panhead of high speed train were investigated and compared with available experimental data and other simulations. The pantograph head was simplified to be a square-cross-section pillar and assumed to be no interference with other bodies. The Reynolds number (Re) was 22,000. The LES(large eddy simulation) of FDS code was applied to solve the momentum equations and the Wener-Wengle wall model was employed to solve the near wall turbulent flow. Smagorinsky model(
=0.2) was used as SGS(subgrid scale) model. The total grid numbers were about 9 millions and the analyzed domain was divided into 12 multi blocks which were communicated with each other by MPI. The time-averaged mainstream flows were calculated and well compared with experimental data. The phased-averaged quantities had also a good agreement with experimental data. The near-wall turbulence should be carefully treated by wall function or direct resolution to get successful application of LES methods.
NUMERICAL ANALYSIS OF THE AIRFOIL IN SELF-PROPELLED FISH MOTION USING IMMERSED BOUNDARY LATTICE BOLTZMANN METHOD
Kim, Hyung-Min ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 24~29
DOI : 10.6112/kscfe.2011.16.2.024
Immersed boundary lattice Boltzmann method has been applied to analyze the characteristics of the self-propelled fish motion swimming robot. The airfoil NACA0012 with caudal fin stroke model was considered to examine the characteristics. The foil in steady forward motion and a combination of steady-state harmonic deformation produces thrust through the formation of a flow downstream from the trailing edge. The harmonic motion of the foil causes unsteady shedding of vorticity from the trailing edge, while forming the vortices at the leading edge as well. The resultant thrust is developed by the pressure difference formed on the upper and lower surface of the airfoil. and the time averaged thrust coefficient increases as Re increase in the region of
. The suggested numerical method is suitable to develop the fish-motion model to control the swimming robot, however It would need to extend in 3D analysis to examine the higher Re and to determine the more detail mechanism of thrust production.
THE DEVELOPMENT AND ASSESSMENT STRATEGY OF A THERMAL HYDRAULICS COMPONENT ANALYSIS CODE
Park, I.K. ; Cho, H.K. ; Lee, J.R. ; Kim, J. ; Yoon, H.Y. ; Lee, H.D. ; Jeong, J.J. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 30~48
DOI : 10.6112/kscfe.2011.16.2.030
A three-dimensional thermal-hydraulic code, CUPID, has been developed for the analysis of transient two-phase flows at component scale. The CUPID code adopts a two-fluid three-field model for two-phase flows. A semi-implicit two-step numerical method was developed to obtain numerical solutions on unstructured grids. This paper presents an overview of the CUPID code development and assessment strategy. The governing equations, physical models, numerical methods and their improvements, and the systematic verification and validation processes are discussed. The code couplings with a system code, MARS, and, a three-dimensional reactor kinetics code, MASTER, are also presented.
LARGE EDDY SIMULATION OF FULLY TURBULENT WAVY CHANNEL FLOW USING RESIDUAL-BASED VARIATIONAL MULTI-SCALE METHOD
Chang, Kyoung-Sik ; Yoon, Bum-Sang ; Lee, Joo-Sung ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 49~55
DOI : 10.6112/kscfe.2011.16.2.049
Turbulent flows with wavy wall are simulated using Residual-based Variational Multiscale Method (RB-VMS) which is proposed by Bazilves et al(2007) as new Large Eddy Simulation methodology. Incompressible Navier-Stokes equations are integrated using Isogeometric analysis which adopt the basis function as NURBS. The Reynolds number is 6760 based on the bulk velocity and averaged channel height. And the amplitude (
) of wavy wall is 0.05. The computational domain is
in the streamwise, wall normal and spanwise direction. Mean quantities and turbulent statistics near wavy wall are compared with DNS results of Cherukat et al.(1998). The predicted results show good agreement with reference data.
NUMERICAL ANALYSIS TO DESIGN HIGH TEMPERATURE HEAT EXCHANGER OF BETA TYPE STIRLING ENGINE IN 3-D COMBUSTION FIELD
Kang, S.H. ; Kim, H.J. ; Chung, D.H. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 56~61
DOI : 10.6112/kscfe.2011.16.2.056
Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is
-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.
NUMERICAL ANALYSIS ON PRESSURE DROP IN EXPANDED BED ACCORDING TO TUBE-TO-PARTICLE RATIOS AND REYNOLDS NUMBERS
Bae, S.W. ; Sung, H.G. ; Roh, T.S. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 62~65
DOI : 10.6112/kscfe.2011.16.2.062
Characteristics of the pressure drop in an expanded bed have been compared to those in a packed bed for numerical study of the interphase drag in gas-particle flows. A numerical analysis of the pressure drop by the particle drag has been conducted according to the tube-to-particle diameter ratios and Reynolds numbers for comparison. As the tube-to-particle diameter ratios increase at the same Reynolds number, the pressure drop tends to converge. It has been confirmed that characteristics of the pressure drop in the expanded bed are similar to those in the packed bed.
NUMERICAL STUDY ON THE EROSION CHARACTERISTICS OF SCR CATALYST DUCT BY VARYING ITS GEOMETRICAL CONFIGURATION
Park, Hun-Chae ; Choi, Hang-Seok ; Choi, Yeon-Seok ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 66~74
DOI : 10.6112/kscfe.2011.16.2.066
The SCR catalyst in coal-fired power plant is eroded by the collision of fly ash on the catalyst surface. However the erosion of SCR catalyst by the collision of fly ash has not been fully studied, especially in terms of fluid dynamics. Hence, in the present study, we focus on the gas and solid flows inside the SCR catalyst duct and their consequent effect on the erosion characteristics. For this purpose, computational fluid dynamics is applied to investigate the two-phase flows and to evaluate the erosion rate for different flow and particle injection conditions. Also, the erosion rate and pressure drop of commonly used square shape are compared with equilateral triangle and hexagon shapes. The pressure drop of SCR catalyst is increased when SCR catalyst surface area per unit volume increases. The erosion rate of SCR catalyst is enhanced when the particle velocity, mass flow rate of particle, particle diameter and cell density of SCR catalyst are increased. From the results, the pressure drop and erosion rate at the catalyst surface can be minimized by reducing cell density of SCR catalyst to decrease particle velocity and number of particle impacts.
A NUMERICAL STUDY FOR IMPROVING PERFORMANCE ON PAINT DRYING SYSTEM OF A VEHICLE
Lee, Seung-Jae ; Choi, Jong-Rak ; Hur, Nahm-Keon ; Kim, Hee-Soo ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 75~80
DOI : 10.6112/kscfe.2011.16.2.075
In this study, three-dimensional transient numerical simulations were carried out for a paint drying system of vehicle. The vehicle on assembly line passes through the drying system consisting of hot and cool air blow region. For the moving motion of the vehicle, moving of inlet boundary condition and MRF technique are used. The transient distribution of temperature and velocity in the drying system were predicted numerically. In order to validate the numerical results, transient distribution of the vehicle surface temperature was compared with experimental data, showing a good agreement. As a result of present study, optimal operating condition of the drying system are to be suggested.
EFFEECTS OF NON-NEWTONIAN FLUID MODEL ON HEMODYNAMICS IN CEREBRAL SACCULAR ANEURYSMS
Park, J.S. ; Lee, S.W. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 81~87
DOI : 10.6112/kscfe.2011.16.2.081
The importance of shear thinning non-Newtonian blood rheology on the hemodynamic characteristics of idealized cerebral saccular aneurysms were investigated by carrying out CFD simulations assuming two different non-Newtonian rheology models (Carreau and Ballyk models). To explore effects of vessel curvature, a straight and a curved vessel geometry were considered. The wall shear stress(WSS), relative residence time(RRT) and velocity distribution were compared at the different phases of cardiac cycle. As expected, blood entered the aneurysm at the distal neck and created large vortex in both aneurysms, but with higher momentum on the curved vessel. Hemodynamic characteristics such as WSS, and RRT exhibited only minor effects by choice of different rheological models although Ballyk model produced relatively higher effects. We conclude that the assumption of Newtonian fluid is reasonable for studies aimed at quantifying the hemodynamic characteristics, in particular, WSS-based parameters, considering the current accuracy level of medical image of cerebral aneurysm.
TRANSIENT SIMULATION OF SUBCOOLED ONSET OF NUCLEATE BOILING IN A MICRO-CHANNEL
Lee, H.J. ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 88~93
DOI : 10.6112/kscfe.2011.16.2.088
A numerical study of subcooled onset of nucleate boiling (ONB) in a micro-channel under pulsed heating using volume of fluids (VOF) model was conducted. The VOF simulation adopting the existing experimental condition is compared to the experimental data. The time to ONB was determined when the void fraction at the microheater surface first appeared. The theoretical superheat for homogeneous nucleation relatively predicts the transient ONB results of convective flow of water well based on local temperature distribution. It was found that once heat load increases at the heater, transient flow boiling starts to occur faster.
THE FAST PYROLYSIS CHARACTERISTICS OF LIGNOCELLULOSIC BIOMASS IN A BUBBLING FLUIDIZED BED REACTOR
Choi, Hang-Seok ;
Journal of computational fluids engineering, volume 16, issue 2, 2011, Pages 94~101
DOI : 10.6112/kscfe.2011.16.2.094
The fast pyrolysis characteristics of lignocellulosic biomass are investigated for a bubbling fluidized bed reactor by means of computational fluid dynamics (CFD). To simulate multiphase reacting flows for gases and solids, an Eulerian-Eulerian approach is applied. Attention is paid for the primary and secondary reactions affected by gas-solid flow field. From the result, it is scrutinized that fast pyrolysis reaction is promoted by chaotic bubbling motion of the multiphase flow enhancing the mixing of solid particles. In particular, vortical flow motions around gas bubbles play an important role for solid mixing and consequent fast pyrolysis reaction. Discussion is made for the time-averaged pyrolysis reaction rates together with time-averaged flow quantities which show peculiar characteristics according to local transverse location in a bubbling fluidized bed reactor.