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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 7, Issue 4 - Dec 2002
Volume 7, Issue 3 - Sep 2002
Volume 7, Issue 2 - Jun 2002
Volume 7, Issue 1 - Mar 2002
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A Study on Delay and Modification in Predicting Turbulence Flow in PISG Algorithm
Lee J. W. ; Ryou H. S. ; Kang K. G. ;
Journal of computational fluids engineering, volume 7, issue 1, 2002, Pages 1~9
In this paper, a modification of PISO algorithm based on standard k-ε turbulence model was proposed. The numerical technique used in this research is finite volume method, hybrid scheme for discretizing convection term, Euler implicit scheme for discretizing time term, and non-staggered grid. The basic idea of the modification of PISO algorithm is to perform an additional corrector stage for turbulence kinetic energy and dissipation rate to correct the inconsistence of flow and turbulence. In order to validate this algorithm, simulation of flow around a square cylinder (Re=3000) was performed in two-dimensional case. The results obtained from the proposed scheme show better agreement with those from the experiment than using original PISO algorithm in coherent velocity field.
A Study of Non-staggered Grid Approach for Incompressible Heat and Fluid Flow Analysis
Kim Jongtae ; Kim Sang-Baik ; Kim Hee-Dong ; Maeng Joo-sung ;
Journal of computational fluids engineering, volume 7, issue 1, 2002, Pages 10~19
The non-staggered(collocated) grid approach in which all the solution variables are located at the centers of control volumes is very popular for incompressible flow analyses because of its numerical efficiency on the curvilinear or unstructured grids. Rhie and Chow's paper is the first in using non-staggered grid method for SIMPLE algorithm, where pressure weighted interpolation was used to prevent decoupling of pressure and velocity. But it has been known that this non-staggered grid method has stability problems when pressure fields are nonlinear like in natural convection flows. Also Rhie-Chow scheme generates large numerical diffusion near curved walls. The cause of these unwanted problems is too large pressure damping term compared to the magnitude of face velocity. In this study the magnitude of pressure damping term of Rhie-Chow's method is limited to 1∼10% of face velocity to prevent physically unreasonable solutions. The wall pressure extrapolation which is necessary for cell-centered FVM is another source of numerical errors. Some methods are applied in a unstructured FV solver and analyzed in view of numerical accuracy. Here, two natural convection problems are solved to check the effect of the Rhie-Chow's method on numerical stability. And numerical diffusion from Rhie-Chow's method is studied by solving the inviscid flow around a circular cylinder.
Numerical Prediction of Turbulent Flow over a Circular Cylinder
Park T. S. ;
Journal of computational fluids engineering, volume 7, issue 1, 2002, Pages 20~27
Flow over a circular cylinder is studied numerically using a turbulence model. Based on the κ-ε-f/sub μ/ model of Park and Sung, a new damping function is used. The efficiency of the strain dependent damping function is addressed for vortex-shedding flows past a circular cylinder. The mean velocity and Reynolds stresses are compared with available experimental data at Re/sub D/= 3900. Also, the computational results for the Strouhal number are evaluated at several Reynolds number. The predictions by κ-ε-f/sub μ/ model are in good agreement with the experiments.
Natural Convection from the Concave Wall in a Square Enclosure
Park T. S. ;
Journal of computational fluids engineering, volume 7, issue 1, 2002, Pages 28~35
The effect of concave curvature on the natural convection has been numerically studied using the higher-order finite difference method. The heating wall in a enclosure is approximated by a cosine function. The heat transfer coefficient is analyzed for three Rayleigh numbers and five amplitudes. For Ra = 10/sup 8/ the separation and reattachment are observed on the adiabatic walls. The wall heat transfer are slightly changed by the increasing curvatures.
Enhancement of Mass Transfer of an Enclosed Fluid by Time-periodic Thermal Forcing
Kwak H. S. ;
Journal of computational fluids engineering, volume 7, issue 1, 2002, Pages 36~43
A numerical investigation is made of unsteady double-diffusive convection of a Boussinesq fluid in a rectangular cavity subject to time-periodic thermal excitations. The fluid is initially stratified between the top endwall of low solute concentration and the bottom endwall of high solute concentration. A time-dependent heat flux varying in a square wave fashion, is applied on one sidewall to induce buoyant convection. The influences of the imposed periodicity on double-diffusive convection are examined. A special concern is on the occurrence of resonance that the fluctuations of flow and attendant heat and mass transfers are mostly amplified at certain eigenmodes of the fluid system. Numerical solutions illustrate that resonant convection results in a conspicuous enhancement of time-mean mass transfer rate.