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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 5, Issue 3 - Dec 2000
Volume 5, Issue 2 - Sep 2000
Volume 5, Issue 1 - May 2000
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Numerical Analysis Method for the Flow Analysis in the Engine Cylinder
Choi J. W. ; Lee Y. H. ; Park C. K. ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 1~7
In general, FDM(finite difference method) and FVM(finite volume method) are used for analyzing the fluid flow numerically. However it is difficult to apply them to problems involving complex geometries, multi-connected domains, and complex boundary conditions. On the contrary, FEM(finite element method) with coordinates transformation for the unstructured grid is effective for the complex geometries. Most of previous studies have used commercial codes such as KIVA or STAR-CD for the flow analyses in the engine cylinder, and these codes are mostly based on the FVM. In the present study, using the FEM for three-dimensional, unsteady, and incompressible Navier-Stokes equation, the velocity and pressure fields in the engine cylinder have been numerically analyzed. As a numerical algorithm, 4-step time-splitting method is used and ALE(arbitrary Lagrangian Eulerian) method is adopted for moving grids. In the Piston-Cylinder, the calculated results show good agreement in comparison with those by the FVM and the experimental results by the LDA.
Numerical Analysis of Sprays in the Combustion Chamber of Diesel Engine
Cha K. S. ; Choi J. W. ; Park C. G. ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 8~13
In this study, the spray models incorporated into the GTT code were tested for sprays injected in quiescent swirling gases and for the sprays impinging on a flat wall, and the validity of the models has been confirmed by comparing the calculated results with the experimental data. Using this code, the gas flow, spray behavior and fuel vapor distributions in the combustion chamber of a D.I engine have been numerically analyzed with respect to the constant injection pressure and the injection pressure varying with injection time.
Orthogonal Grid Generation Using Linear Grid Generating Equations
Lee S. W. ; Kwon J. H. ; Kwon O. J. ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 14~21
A method of two and three dimensional orthogonal grid generation with control of spacing by using the covariant Laplace equation is presented. An important feature of the methodology is its ability to control effectively the grid spacing especially near the boundaries still maintaining good orthogonality in whole field. The method is based on the concept of decomposition of the global transformation into consecutive transformation of an approximate conformal mapping and an auxiliary orthogonal mapping to have linear and uncoupled equations. Control of cell spacing is based on the concept of reference arc length, and orthogonal correction is peformed in the auxiliary domain. It is concluded that the methodology can successfully generate well controlled orthogonal grids around bodies of 2 and 3 dimensional configurations.
Application of Algebraic Stress Model to the Calculation of the Viscous Flow around a Ship
Oh K. J. ; Choi J. E. ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 22~26
The flow around a ship is complex, especially, at the stern region of a full ship, where highly curved streamlines, hook-shaped iso-velocity contours, and strong secondary flow exist. To resolve this complex flow, an Algebraic Stress Model(ASM) is applied. The calculations are performed for the HSVA Tanker. The results are improved comparing with those of standard k-ε turbulence model, but still show a little difference from the experiments.
Heat Transfer and Solidification in the Inviscid Stagnation Flow
Yoo Joo-Sik ; Kim Yong-Jin ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 27~32
This study investigates the problem of phase change from liquid to solid in the inviscid stagnation flow. The instantaneous location of the solid-liquid interface is fixed for all times by a coordinate transformation. Finite difference method is used to obtain the solution of the unsteady problem, and the growth rate of solid and the transient heat transfer from the surfaces of solid are investigated. The transient solution is dependent on the three dimensionless parameters, but the final steady state is determined by only one parameter of temperature ratio/conductivity ratio. It is observed that the instantaneous heat flux at the surface of solid can be obtained with sufficient accuracy by measuring the thickness of the solid or vice versa.
Parametric Study on the
Absorption Process on Horizontal Tubes
Min J. K. ; Choi D. H. ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 33~42
The LiBr-H₂O absorption process on a horizontal tube has been analyzed numerically. The flow field, which was calculated in the authors' previous study by solving the fully elliptic Navier-Stokes equations with accurate free-surface-tracking method, is used to solve the temperature and concentration distributions in the absorption film. With the assumption that the absorbent is linear, calculations have been made for various inlet temperature and flow-rate conditions. For low inlet temperature, the absorption rate is large in the upstream region but the mean temperature also increases and as a result the absorption decreases as the film flows to downstream while high-inlet-temperature case does the opposite. The difference in the absorption rate due to the inlet temperature change becomes smaller in the downstream than that in the upstream. For large flow rate, the heat transfer to the wall becomes poor due to the thick film and so does the absorption rate. The analyses have also been carried out for multiple tube arrangement and the results show that the absorption rate converges after a few tube rows.
Applications of Characteristic Boundary Conditions within CFDS Numerical Framework
Hong S. K. ; Lee K. S. ;
Journal of computational fluids engineering, volume 5, issue 1, 2000, Pages 43~59
Characteristic boundary conditions are discussed in conjunction with a flux-difference splitting formulation as modified from Roe's linearization. Details of how one can implement the characteristic boundary conditions which are made compatible with the interior point formulation are described for different types of boundaries including subsonic outflow and adiabatic wall. The validity of boundary conditions are demonstrated through computation of transonic airfoil, supersonic ogive-cylinder, hypersonic cylinder, and S-duct internal flows. The computed wall pressure distributions are compared with published experimental and computed data. Objectives of this paper are thus to give insight of formulation procedure of a flux-difference splitting method and to pave ways for other users to adopt present boundary procedure on their numerical methods.