• 한국유체기계학회 논문집
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• 제11권3호
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• pp.7-13
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• 2008

The cavitating flow simulation is of practical importance for many engineering systems, such as pump, turbine, nozzle, Infector, etc. In the present work, a solver for two-phase flows has been developed and applied to simulate the cavitating flows past hydrofoils. The governing equation is the two-phase Navier-Stokes equation, comprised of the continuity equation of liquid and vapor phase. The momentum and energy equation is in the mixture phase. The solver employs an implicit, dual time, preconditioned algorithm using finite difference scheme in curvilinear coordinates. An experimental data and other numerical data were compared with the present results to validate the present solver. It is concluded that the present numerical code has successfully accounted for two-phase Navier-Stokes model of cavitation flow.

• 대한화학회지
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• 제40권6호
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• pp.409-414
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• 1996

선형 비평형 열역학의 최소 엔트로피 생성원리를 사용하여 정상 평면충격파 형상에 대한 Navier-Stokes 유체방정식의 적용한계를 연구하였다. 해석적 결과를 얻기 위하여 평형상태에 가까운 하류 위치에서 방정식을 선형화 하였다. 하류 극한의 경계조건을 충족하는 Navier-Stokes 방정식의 해를 충격파 진행속도의 마하수 M=1 근처에서 급수전개하였을 때, 일차항까지는 열역학의 요구조건과 부합하였다.

• 한국전산유체공학회지
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• 제17권1호
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• pp.44-53
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• 2012

Immersed boundary method(IBM) is a numerical scheme proposed to simulate flow field around complex objectives using simple Cartesian grid system. In the previous studies, the IBM has mostly been implemented to fractional step method based Navier-Stokes solvers. In this study, we implement the IBM to an incompressible Navier-Stokes solver which uses SIMPLE algorithm. The weight coefficients of the bi-linear and quadratic interpolation equations were formulated by using only geometric information of boundary to reconstruct velocities near IB. Flow around 2D circular cylinder at Re=40 and 100 was solved by using these formulations. It was found that the pressure buildup was not observed even when the bi-linear interpolation was adopted. The use of quadratic interpolation made the predicted aerodynamic forces in good agreement with those of previous studies. For an analysis of moving boundary, we smulated an oscillating circular cylinder with Re=100 and KC(Keulegan-Carpenter) number of 5. The predicted flow fields were compared with experimental data and they also showed good agreements.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.199-201
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• 2011

NACA0012 Airfoil was simulated with Computational Fluid Dynamics(CFD) and the aerodynamic characteristics was analyzed for various far-field boundary distances ranging from 10 airfoil chord to 50 chord Drag coefficient distribution was dependent on the far-field distance and circulation, integrated along the loop inside the flow region, was also dependent. It was turned out that some corrections based on the circulation should be added to the far-field boundary condition for accurate airfoil simulation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 추계 학술대회논문집
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• pp.91-97
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• 2001

The thin-layer Navier-Stokes equations are solved for the hypersonic flow over blunt cone configurations with applications to laminar as well as turbulent flows. The equations are expressed in the forms of flux-vector splitting and explicit algorithm. The upwind schemes of Steger-Warming and van Leer are investigated in their ability to accurately predict the heating loads along the surface of the body. A comparison with the second order extensions of these schemes is made and a hybrid scheme incorporating a combination of central differencing and flux-vector-splitting is presented. This scheme is also investigated in its ability to accurately predict heat transfer distributions.

• 대한기계학회논문집
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• 제16권2호
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• pp.313-324
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• 1992

Two-dimensional Navier-Stokes code has been developed for analysis of turbomachinery blade rows and other internal flows. The Navier-Stokes equations are written in a Cartesian coordinate system, then mapped into a generalized body-fitted coordinate system. All direction of viscous terms are incorporated and turbulent effects are modeled using the Baldwin-Lomax algebraic model. Equation are discretized using finite difference method on the C-type grids and solved using implicit LU-ADI decomposition scheme. Calculations are made at a VKI turbine cascade flow in a transonic wind-tunnel and compared to experimental data. Present numerical scheme is shown to be in good agreement with the previous experimental results and simulates the two-dimensional viscous flow phenomena.

• 한국전산유체공학회지
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• 제8권4호
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• pp.16-25
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• 2003

The design method for transonic turbine blades has been developed based on Wavier-Stokes equations. The present computing process is done on the four separate steps, i.e., determination of the blade profile, generation of the computational grids, cascade flow simulation and analysis of the computed results in the sense of the aerodynamic performance. The blade shapes are designed using the cubic polynomials under the control of the design parameters. Numerical methods for the flow equations are based on Van-Leer's FVS with an upwind TVD scheme on the finite volume. In the present study, numerical simulation has been done to investigate the effects of the design parameters on the aerodynamic peformance of the axial-flow turbine blades. Applications are made to the VKI transonic rotor blades. Computed results are analyzed with respect to four parameters and compared with the experimental data.

• 한국전산유체공학회지
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• 제10권1호
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• pp.67-72
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• 2005

This research is based on the iterative space-marching method for incompressible and compressible Navier-Stokes equations[1-4]. A principle of parallel computational schemes construction for steady and unsteady problems is suggested. It is analytically proven that convergence of these schemes is unconditional for incompressible case. When the parallel scheme is used the total volume of computations is the sum of a large number of independent and equal parts. Estimation of the speed-up K shows that K > 1000 in ideal case. First results of using the parallel schemes are presented.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.78-83
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• 1998

A finite-difference method based on conservative supra characteristic method(CSCM) type upwind flux difference splitting has been studied on the bluntness effect on the wall heat transfer rate and wall pressure over blunt-body. The results show that the stagnation heating varies inversely with the square root of the nose radius.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.154-159
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• 1995

Numerical optimization technique with Navier-Stokes code has been used to reduce the drag of conventional ogival nose. Forebody optimizations are performed for supersonic laminar and turbulent flow conditions. To alleviate the computing time of aerodynamic drag calculation, axisymmetric boundary condition is implemented in the 3-dimensional Navier-Stokes code. The automated optimization procedure with gradient based method results in a drag reduction of $4\;\%$.