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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 1, Issue 1 - May 1996
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PIGG - Program for Interactive Grid Generation
Seo John S. ; Kim Moon Sang ; Yoon Yong Hyun ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 1~8
Study on effect of control functions according to interpolations for elliptic grid generation method
Chae E. M. ; Sah J. Y. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 9~18
This study examines effect of various interpolations of interior control function for analytic methods such as Thomas-Middlecoff and Sorenson methods. Laplace interpolation is developed and compared among linear interpolation and exponential interpolation systematically
Multiblock Grid Generation for Turbomachinery Cascade-Flow Analysis
Chung H. T. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 19~25
A multiblock grid generation has been developed to be reliably used for a Navier-Stokes simulation of the turbomachinery flow-fields A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid in the tip flow region. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The grid refinement process is enhanced by developing strategies to utilized Bezier curves and splines along with weighted transfinite interpolation technique and by formulating the grid-imbedding method for the viscous boundary-layer meshes. For purposes of illustration, the grid generator is applied to the high turning turbine rotor blades. Two different types of computational grids are provided to be compared with respect to the grid adaptation to the flow simulations. Extension to three-dimensions was done to show the possibility of its application to the tip-flow simulations. The grid quality of the multiblock structure is good in the passages, with gloval orthogonality and adequate smoothness.
A Comparative Study of PISO, SIMPLE, SIMPLE-C Algorithms in 3-dimensional Generalized Coordinate Systems
Park J. Y. ; Baek J. H. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 26~34
The performance of the SIMPLE, SIMPLE-C and PISO algorithms for the treatment of the pressure-velocity coupling in fluid flow problems were examined by comparing the computational effort required to obtain the same level of the convergence. Example problems are circular duct and 90-degree bent square-duct. For circular duct case, laminar and turbulent flow were computed. For 90-degree bent square-duct case, laminar flow was simulated by the time-marching method as well as the iterative method. The convergence speed of the other two algorithms are not always superior to SIMPLE algorithm. SIMPLE algorithm is faster than SIMPLE-C algorithm in the simple laminar flow calculations. The application of the PISO algorithm in three dimensional general coordinates is not so effective as in two-dimensional ones. Since computational time of PISO algorithm is increased at each time step(or iterative step) in three dimension, the total convergence speed is not decreased. But PISO algorithm is stable for large time step by using time marching method,.
Incompressible Laminar Entry Flows in a Square Duct of Strong Curvature Using an Implicit SMAC Scheme
Shin B. R. ; Ikohagi T. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 35~46
Towards Prediction of Unsteady Turbulent Flow over a Square Cylinder using Two-Equation Turbulence Models
Lee Sangsan ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 47~54
Numerical Analysis on Flow Fields and the Calculation of Wave Making Resistance about Air Supported Ships
Na Y. I. ; Lee Y.-G. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 55~63
Numerical computations are carried out to analyze the characteristics of flow fields around Air Supported Ships. The computations are performed in a rectangular grid system based on MAC(Marker And Cell) method. The governing equations are represented in finite difference forms by forward differencing in time and centered differencing in space except for its convection terms. For the certification of this numerical analysis method, the computations of flow fields around a Catamaran, an ACV(Air Cushion Vehicle) modeled with pressure distribution on free surface and two SES(Surface Effect Ship)'s are carried out, The results of the present computations are compared with the previously presented computational and experimental results in the same condition.
A Study on Turbulent Flow Fields around Ships
Lee S. H. ; Park J. J. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 64~70
Three dimensional turbulent flow fields around ships are simulated by a numerical method. Reynolds Averaged Navier-Stokes equations are used where Reynolds stresses are approximated by Baldwin-Lomax and Sub-Grid Scale(SGS) turbulence models. Body-fitted coordinate system is introduced to conform three dimensional ship geometries. The governing equations are discretized by a finite volume method. Temporal derivatives are approximated by the forward differencing and the convection terms are approximated by the QUICK or Kawamura scheme. The 2nd-order centered differencing is used for other spatial derivatives. Pressure and velocity fields are simultaneously iterated by the Highly Simplified Marker-And-Cell method. To verify the numerical method and turbulence models, flow fields around ships are simulated and compared to the experiments.
Numerical Analysis of 3-D Turbulent Flows Around a High Speed Train Including Cross-Wind Effects
Jung Y. R. ; Park W. G. ; Ha S. D. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 71~80
An iterative time marching procedure for solving incompressible turbulent flow has been applied to the flows around a high speed train including cross-wind effects. This procedure solves three-dimensional unsteady incompressible Reynolds-averaged Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using first-order accurate schemes for the time derivatives and third/second-order accurate schemes for the spatial derivatives. Turbulent flows have been modeled by Baldwin-Lomax turbulent model. To validate present procedure, the flow around a high speed train at zero yaw angle was simulated and compared with experimental data. Generally good agreement with experiments was achieved. The flow fields around the high speed train at 9.2°, 16.7°, and 45° of yaw angle were also simulated.
Numerical Flow Simulations Around High Speed Train Using CHIMERA Grid Technique
Choi S. W. ; Kim I. S. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 81~87
The aerodynamic charateristics of high speed train can be improved by well-designing of its fore-body shape. In this paper, as a way of the design a fore-body shape which has optimal aerodynamic charasteristics, 9 models of fore-body shapes are proposed and the change of aerodynamic charateristics is studied through calculations of flow field around high speed train for each fore-body shape. The flow field around high speed trains are calculated using Thin-Layer Navier-Stokes equation and Chimera grid technique. The application of Chimera grid technique to these flow calculations over high speed train which has ground plane under the train makes grid generation easily. As a computaional algorithm, Pulliam and Chaussee's Diagonal algorithm, the modified form of the Beam and Warming's AF scheme which operates on block-tridiagonal matrices, is selected to reduce computaional time. Introducing hole points flag concept to this Diagonal algorithm. a algorithm for Chimera grid is generated. The variational trends of aerodynamic characteristics are studied from the results of flow calculations around high speed trains for 9 fore-body shapes.
Adaptive Triangular Finite Element Method for Compressible Navier - Stokes Flows
Im Y. H. ; Chang K. S. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 88~97
This paper treats an adaptive finite-element method for the viscous compressible flow governed by Navier-Stokes equations in two dimensions. The numerical algorithm is the two-step Taylor-Galerkin mettled using unstructured triangular grids. To increase accuracy and stability, combined moving node method and grid refinement method have been used for grid adaption. Validation of the present algorithm has been made by comparing the present computational results with the existing experimental data and other numerical solutions. Four benchmark problems are solved for demonstration of the present numerical approach. They include a subsonic flow over a flat plate, the Carter flat plate problem, a laminar shock-boundary layer interaction. and finally a laminar flow around NACA0012 airfoil at zero angle of attack and free stream Mach number of 0.85. The results indicates that the present adaptive triangular grid method is accurate and useful for laminar viscous flow calculations.
Numerical Simulation of Asymmetric Vortical Flows on a Slender Body at High Incidence
Rho Oh Hyun ; Hwang Soo Jung ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 98~111
The compressible laminar and turbulent viscous flows on a slender body in supersonic speed as well as subsonic speed have been numerically simulated at high angle of attack. The steady and time-accurate compressible thin-layer Navier-Stokes code based on an implicit upwind-biased LU-SGS algorithm has been developed and specifically applied at angles of attack of 20, 30 and 40 dog, respectively. The modified eddy-viscosity turbulence model suggested by Degani and Schiff was used to simulate the case of turbulent flow. Any geometric asymmetry and numerical perturbation have not been intentionally or artificially imposed in the process of computation. The purely numerical results for laminar and turbulent cases, however, show clear asymmetric formation of vortices which were observed experimentally. Contrary to the subsonic results, the supersonic case shows the symmetric formation of vortices as indicated by the earlier experiments.
A New Pressure-Based PISO-Finite Element Method for Navier-Stokes Equations in All Speed Range
Shim E. B. ; Chang K. S. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 112~122
A finite element scheme using the concept of PISO method has been developed to solve the Navier-Stokes viscous flows in all speed range. This scheme includes development of new pressure equation that retains both the hyperbolic term related with the density variation and the elliptic term reflecting the incompressibility constraint. The present method is applied to the incompressible two-dimensional driven cavity flow problems(Re=100, 400 and 1,000). For compressible flows, the Carter plate problem(M=3 and Re=1,000) is computed. Finally, we have simulated the shock-boundary layer interaction(M=2 and Re=2.96×10/sup 5/), a more difficult problem, and compared its results with the experiment to demonstrate the shock capturing capability of the present solution algorithm.
A Numerical Analysis of High Speed Flow over Blunt Body Using Upwind Navier-Stokes Method
Kwon C. O. ; Kim S. D. ; Song D. J. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 123~141
In this paper the upwind flux difference splitting Navier-Stokes method has been applied to study the perfect gas and the equilibrium chemically reacting hypersonic flow over an axisymmetric sphere-cone(5°) geometry. The effective gamma(γ), enthalpy to internal energy ratio was used to couple chemistry with the fluid mechanics for equilibrium chemically reacting air. The test case condition was at altitude(30km) and Mach number(15). The equilibrium shock thickness over the blunt body region was much thinner than that of perfect gas shock. The pressure difference between perfect gas and equilibrium gas was about 3 ∼ 5 percent. The heat transfer coefficient were also calculated. The results were compared with VSL results in order to validate the current numerical analysis. The results from current method were compared well VSL results ; however, not well at near nose. The proper boundary condition and grid system will be studied to improve the solution quality.
Numerical Investigation for the Optimization of Two-Dimensional Adaptive Wall
Chang B. H. ; Chang K. S. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 134~141
Wall interference is one of the major obstacles to increase the model size and data accuracy. There have been many treatments for wall interference including interference correction and adaptive wall test section. Recently, two-flexible-walled adaptive wall test section is concluded adequate for three-dimensional test. But proper location of target line and pressure holes are critical to its success. In this study, a new adaptive algorithm which dispenses target line and dependency of pressure hole distribution is suggested. The wind tunnel and free air tests are simulated by the numerical computation of Euler equations. The optimum wall shape is achieved by two variable optimization which is composed of two base streamlines. The wall interference is reduced well in the optimized result which is not sensitive to the base streamlines.
Comparison of FDDO and DSMC Methods in the Analysis of Expanding Rarefied Flows
Chung C. H. ;
Journal of computational fluids engineering, volume 1, issue 1, 1996, Pages 142~149