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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 10, Issue 4 - Dec 2005
Volume 10, Issue 3 - Sep 2005
Volume 10, Issue 2 - Jun 2005
Volume 10, Issue 1 - Mar 2005
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EVALUATION OF TURBULENCE MODELS FOR ANALYSIS OF THERMAL STRIPING
Cho, Seok-Ki ; Kim, Se-Yun ; Kim, Seong-O ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 1~11
A numerical study of the evaluation of turbulence models for thermal striping phenomenon is performed. The turbulence models chosen in the present study are the two-layer model, the shear stress transport (SST) model and the V2-f model. These three models are applied to the analysis of the triple-jet flow with the same velocity but different temperatures. The unsteady Reynolds-averaged Navier-Stokes (URANS) equation method is used together with the SIMPLEC algorithm. The results of the present study show that the temporal oscillation of temperature is predicted by the SST and V2-f models, and the accuracy of the mean velocity, the turbulent shear stress and the mean temperature is a little dependent on the turbulence model used. In addition, it is shown that both the two-layer and SST models have nearly the same capability predicting the thermal striping, and the amplitude of the temperature fluctuation is predicted best by the V2-f model.
EVALUATION OF TURBULENCE MODELS FOR ANALYSIS OF THERMAL STRATIFICATION
Cho, Seok-Ki ; Kim, Se-Yun ; Kim, Seong-O ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 12~17
A computational study of evaluation of current turbulence models is performed for a better prediction of thermal stratification in an upper plenum of a liquid metal reactor. The turbulence models tested in the present study are the two-layer model, the shear stress transport (SST) model, the v2-f model and the elliptic blending mode(EBM). The performances of the turbulence models are evaluated by applying them to the thermal stratification experiment conducted at JNC (Japan Nuclear Corporation). The algebraic flux model is used for treating the turbulent heat flux for the two-layer model and the SST model, and there exist little differences between the two turbulence models in predicting the temporal variation of temperature. The v2-f model and the elliptic blending model better predict the steep gradient of temperature at the interface of thermal stratification, and the v2-f model and elliptic blending model predict properly the oscillation of the ensemble-averaged temperature. In general the overall performance of the elliptic blending model is better than the v2-f model in the prediction of the amplitude and frequency of the temperature oscillation.
NUMERICAL SIMULATION OF LID-DRIVEN FLOW IN A SQUARE CAVITY AT HIGH REYNOLDS NUMBERS
Myong H. K. ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 18~23
Numerical simulations of two-dimensional steady incompressible lid-driven flow in a square cavity are presented by a new solution code(PowerCFD) which adopts an unstructured cell-centered method. Solutions are obtained for configurations with a Reynolds number as high as 10,000 with both rectangular and hybrid types of unstructured grid mesh in order to validate the code's independency of grid type. Interesting features of the flow are presented in detail and comparisons are made with benchmark solutions found in the literature. It is found that the code is capable of producing accurately the nature of the lid-driven cavity flow at high Reynolds numbers with no grid type dependency.
NUMERICAL SIMULATION OF UNSTEADY MISSILE STAGING SYSTEM
Yoon Y. H. ; Kwon K. B. ; Hong S. K. ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 24~31
A dynamic simulation on the missile staging system is conducted with numerical techniques. Both Euler equations and Navier-Stokes equations are numerically solved respectively. The dynamic simulation of two moving bodies is fully integrated into the computational fluid dynamics solution procedure. The Chimera grid scheme is applied in this simulation for unsteady supersonic flow analysis with dynamic modeling. The objective of the study is to investigate the problem pertaining to possible unstability in missile staging. In addition, the computational comparison between in viscid and viscid flow solvers is also performed in this study.
EFFICIENT SIMULATION AND SCALING OF OSCILLATORY IMPINGING JETS
Kim S. I. ; Park S. O. ; Hong S. K. ; Lee K. S. ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 32~38
Present study simulates oscillatory supersonic impinging jet flows using the axisymmetric Navier-Stokes code. To capture the salient features of flow oscillation and overcome the divergence during the initial transient period, several tests have been conducted for the grid and time step sizes. The results also show that the effects of the inlet flow condition at the nozzle exit and turbulence on the oscillatory behavior of supersonic impinging jets are negligible. Frequencies of the surface pressure oscillation obtained by the selected numerical method are in good accord with the measured impinging tones for various cases of nozzle-to-plate distance. Two seemingly different staging behaviors with nozzle-to-plate distance and nozzle pressure variations are found to correlate well if the frequency and distance are normalized by the length of the first shock cell.
TURBULENT FLOW SIMULATIONS ABOUT THE AIRCRAFT CONFIGURATION
Kim YoonSik ; Park Soo Hyung ; Kwon Jang-Hyuk ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 39~50
An application of the KFLOW3D code which has been developed at KAIST is presented. This paper briefly describes the underlying methodology and summarizes the results for the DLR-F6 transport configuration recently presented in the second AIAA CFD Drag Prediction Workshop held in Orlando, FL, June 2003. KFLOW3D is a parallelized Reynolds averaged Navier-Stokes solver for multi-block structured grids. For the present computations, 2-equation k-
WD+ nonlinear eddy viscosity model is used. The emphasis of the paper is placed on the implementation of the k-
WD+ model in the multigrid framework and practicality of KFLOW3D for accurately predicting not only the integrated aerodynamic property such as the drag coefficient but pressure distributions.
TWO- AND THREE-DIMENSIONAL SUPERSONIC TURBULENT FLOW OVER A SINGLE CAVITY
Woo C. H. ; Kim J. S. ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 51~58
The unsteady supersonic flow over two- and three-dimensional cavities has been analyzed by the integration of unsteady Reynolds-Averaged Navier-Stokes(RANS) with the k-
turbulence model. The unsteady flow is characterized by the periodicity due to the mutual relation between the shear layer and the internal flow in the cavity. An explicit 4th order Runge-Kutta scheme and an upwind TVD scheme based on the flux vector split with the van Leer limiters are used for time and space discritizations, respectively. The cavity has a L/D ratio of 3 for two-dimensional case, and same L/D and W/D ratio of I for three-dimensional case. The Mach and Reynolds numbers are 1.5 and 450000 respectively. In the three-dimensional flow, the field is observed to oscillate in the 'shear layer mode' with a feedback mechanism that follows Rossiter's formula. In the two-dimensional simulation, the self-sustained oscillating flow has more violent fluctuation inside the cavity. The primary fluctuating frequencies of two- and three- dimensional flow agree very well with the 2nd mode of Rossiter's frequency. In the three-dimensional flow, the 1st mode of frequency could be seen.
NUMERICAL ANALYSIS FOR A SILENCER OF TANK GUN
Ko S. H. ; Lee D. S. ; Woo S. D. ; Kang K. J. ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 59~65
A numerical analysis was made to investigate the simple silencer for high pressure blast flow fields. Reynolds-Averaged Navier-Stokes equations were solved for an axisymmetric computational domain constructed by multi block grids. A blast flow field without the silencer was also calculated to validate the present numerical method. The effect of pressure diminution for the silencer was calculated by comparing with and without silencer at the atmosphere region. It was found that the tested silencer could achieve 89.4 percent pressure diminution.
FLOW DISTRIBUTION IN THE CORE OF HANARO AFTER SUPPRESSING THE JET FLOW IN THE GUIDE TUBE USED FOR LOADING FISSION MOLY TARGET
Park Yong Chul ; Lee Byung Chul ; Kim Bong Soo ; Kim Kyung Ryun ;
Journal of computational fluids engineering, volume 10, issue 4, 2005, Pages 66~71
HANARO, a multi-purpose research reactor, 30 MWth open-tank-in-pool type, is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and a target handling tool is under development for loading and unloading it in a circular flow tube (OR-5) of HANARO. A guide tube is extended from the reactor core to the top of the reactor chimney for easily loading the target under a normal operation of the reactor. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube. The jet flow was suppressed in the guide tube after reducing the inner diameter of a flow restriction orifice installed in the OR-5 flow tube for adding the pressure difference in the flow tube. This paper describes an analytical analysis to calculate the flow distribution in the core of HANARO after suppressing the jet flow of the guide tube. As results, it was confirmed through the analysis results that the flow distribution in the core of HANARO were not adversely affected.