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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 9, Issue 4 - Dec 2004
Volume 9, Issue 3 - Sep 2004
Volume 9, Issue 2 - Jun 2004
Volume 9, Issue 1 - Mar 2004
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Simulation of Low-Speed Rarefied Gas Flows Around a Flat Plate
Chung C. H. ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 1~7
A kinetic theory analysis is made of low-speed rarefied gas flows around a flat plate. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the discrete ordinate method. The method does not suffer from statistical noise which is common in particle based methods and requires much less amount of computational effort. Calculations are made for flows around a micro-scale flat plate with a finite length of 20 microns. The method is assessed by comparing the results with those from several different methods and available experimental data.
Numerical Simulation for the Advection Equation on the Sphere by Sphere-Lagrangian Method
Yoon Seong Y. ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 8~17
A Semi-Lagrangian method based on CIP(Cubic Interpolated Pseudoparticle)method is proposed and it is applied to solve the two dimensional advection equation. Especially the attentions are given to settle the pole problem and to enhance the accuracy in solving the advection equation on the spherical coordinate system. Tn this algorithm, the CU method is employed as the Semi-Lagrangian method and extended to the spherical coordinate system. To enhance the accuracy of the solution, the spatial discretization is made by CIP method. The mathematical formulation and numerical results are also described. To verify the efficiency, accuracy and capability of proposed algorithm, two dimensional rotating cosine bell problem and the frontogenesis problem are simulated by the present scheme. As results, it is confirmed that the present scheme gives an accurate solution and settles the pole problem in the advection equation on the sphere.
Numerical Prediction of the Base Heating due to Rocket Engine Clustering
Kim Seong Lyong ; Kim Insun ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 18~25
Multi plume effects on the base heating have been Investigated with a CFD program. As the flight altitude increases, the plume expansion angle increases regardless of the single or clustered engine. The plume interaction of the clustered engine makes a high temperature thermal shear in the center of four plumes. At low altitude, the high temperature shear flow stays in the center of plumes, but it increases up to engine base with the increasing altitude. At high altitude, the flow from plume to base and the flow from base into outer free stream are supersonic, which transfers the high heat in the center of plumes to the base region. The radiative heat of the clustered engine varies from 220 kW/m² to 469 kW/m² with increasing altitude while those of the single engine are 10 kW/m² and 43.7 kW/m². And the base temperature of the clustered engine varies from 985K to 1223K, and those of the single engine are 483K and 726K. This big radiative heat of clustered engine can be explained by the active high temperature base flow and strong plume interactions.
Robust and Efficient LU-SGS Scheme on Unstructured Meshes: Part I - Implicit Operator
Kim Joo Sung ; Kwon Oh Joon ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 26~38
A study has been made for the investigation of the robustness and convergence of various implicit operators of the LU-SGS scheme using linear stability analysis. It is shown that the behavior of the implicit operator is not determined by its own characteristics, but is determined relatively depending on the dissipative property of the explicit operator. It is also shown that, as the dissipation level of the implicit operator increases, the robustness of the scheme increases, but the convergence rate can be deteriorated due to the excessive dissipation. The numerical results demonstrate that the dissipation level of the impliict operator needs to be higher than that of the explicit operator for computing stiff problems.
Robust and Efficient LU-SGS Scheme on Unstructured Meshes: Part Ⅱ - Efficient Implementation
Kim Joo Sung ; Kwon Oh Joon ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 39~48
In the present study, an efficient implementation technique of the van Leer's implicit operator is suggested in accordance with the Roe's explicit operator. By using an efficient treatment of the off-diagonal terms, which occupy most of the memory requirement for the linear system of equations, it is shown that the improved scheme only requires less than 30% of memory and is approximately 10-20% faster than the baseline scheme.
Heat Exchanger Design Analysis for Propellant Pressurizing System of Satellite Launch Vehicles
Lee H. J. ; Han S. Y. ; Chung Y. G. ; Cho N. K. ; Kil G. S. ; Kim Y. K. ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 49~56
A heated and expanded helium is used to pressurize liquid propellants in propellant tanks of propulsion system of liquid propellant launch vehicles. To produce a heated and expanded helium, an hot-gas heat exchanger is used by utilizing heat source from an exhausted gas, which was generated in a gas generator to operate turbine of turbo-pump and dumped out through an exhaust duct of engine. Both experimental and numerical approaches of hot-gas heat exchanger design were conducted in the present study. Experimentally, siliconites - electrical resistance types - were used to simulate the full heat condition instead of an exhausted gas. Cryogenic heat exchangers, which were immersed in a liquid nitrogen pool, were used to feed cryogenic gaseous helium in a hot-gas heat exchanger. Numerical simulation was made using commercially utilized solver - Fluent V.6.0 - to validate experimental results. Helically coiled stainless steel pipe and stainless steel exhausted duct were consisted of tetrahedron unstructured mesh. Helium was a working fluid Inside helical heat coil and regarded as an ideal gas. Realizable k-』 turbulent modeling was adopted to take turbulent mixing effects in consideration. Comparisons between experimental results and numerical solutions are Presented. It is observed that a resulted hot-gas heat exchanger design is reliable based on the comparison of both results.
An Incompressible Flow Computation by a Hierarchical Iterative and a Modified Residual Method
Kim J. W. ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 57~65
The incompressible Navier-Stokes equations in two dimensions are stabilized by a modified residual method, and then discretized by hierarchical elements. The stabilization is necessary to escape from the Ladyzhenskaya-Babuska-Brezzi(LBB) constraint and hence to achieve an equal order formulation. To expedite a standard iterative method such as the conjugate gradient squared(CGS) method, a preconditioning technique called the Hierarchical Iterative Procedure(HIP) has been applied. In this paper, we increased the order of interpolation within an element up to cubic. The hierarchical elements have been used to achieve a higher order accuracy in fluid flow analyses, but a proper efficient iterative procedure for higher order finite element formulation has not been available so far The numerical results by the present HIP for the lid driven cavity flow and others showed the present procedure to be stable, very efficient and useful in flow analyses in conjunction with hierarchical elements.
Thermal Contact Resistance of Two Bodies in Contact
Kwak Hong Sup ; Jeong Jae Tack ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 66~72
Development of a 3-D CFD Program for Computing Two-Phase Flows with a Level Set Method
Son G. ; Hur N. ;
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 73~80
A LS(Level Set) formulation is developed for computing two-phase flows on non- orthogonal meshes. Compared with the VOF(Volume-of-Fluid) method based on a non-smooth volume-fraction function, the LS method can calculate an interfacial curvature more accurately by using a smooth distance function. Also, it is quite straightforward to implement for 3-D irregular meshes compared with the VOF method requiring much more complicated geometric calculations. The LS formulation is implemented into a general purpose program for 3-D flows and verified through several test problems.
한국항공우주연구원 회전익관련 전산유동해석 분야 소개
Journal of computational fluids engineering, volume 9, issue 3, 2004, Pages 81~84