• 한국전산유체공학회:학술대회논문집
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• 1999.05a
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• pp.106-112
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• 1999

In this article, combination of the FAS-FMG multi-grid method and the Krylov subspace method was presented in solving two dimensional driven-cavity flows. Three algorithms of the Krylov subspace method, CG, CGSTAB(Bi-CG Stabilized) and GMRES method were tested with MILU preconditioner. As a smoother of the pressure correction equation, the MILU-CG is recommended rather than MILU-GMRES(k) or MILU-CGSTAB, since the MILU-GMRES(k) preconditioner has too much computation on the coarse grid compared to the MILU-CG one. As for the momentum equation, relatively cheap smoother like SIP solver may be sufficient.

• 한국전산유체공학회:학술대회논문집
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• 1999.05a
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• pp.113-123
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• 1999

In this study a pure vector potential method (PVPM) for a three dimensional, unsteady, incompressible flow is proposed. A simplified version for a two dimensional problem is described in detail, and a method to prescribe appropriate boundary conditions is also presented. The resulting numerical algorithm is applied to the cavity flow driven by an impulsively started wall and also to the Stokes' first problem. Some important unsteady/steady features are captured for these two flows, and quantitative agreements of flow variables with available reference database are good.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.152-157
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• 2003

As computer capacity has been progressed continuously, the studies of the flow characteristics have been performing by the numerical methods actively. Recent numerical simulation has a tendency to require the higher-order accuracy in time, as well as in space. This tendency is more true in LES and acoustic noise simulation. In this study, 3-dimensional unsteady Incompressible Navier-Stokes equation was solved by numerical method using the fractional step method with the fourth order compact pade scheme to achieve high accuracy To validate the present code and algorithm, 3D flow-field around a cylinder was simulated. The drag coefficient and lift coefficient were computed and, then, compared with experiment. The present code will be tailored to LES simulation for more accurate turbulent flow analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.349-352
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• 2010

A study is analyzed on the transient flow of supersonic diffuser and performed on the of supersonic diffuser with Computational Fluid Dynamic. The flow field of supersonic diffuser is calculated using Axisymmetric two-dimensional Navier-Stokes equation with $k-{\epsilon}$ turbulence model. The transient simulation is compared in terms of mach number and temperature of vacuum chamber according to the chamber pressure of starting transient on Liquid rocket engine.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.174-180
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• 2002

A virtual reality technology for multipurpose numerical simulation is developed to reproduce and investigate a variety of ocean environmental problems in a 3D-Numerical Wave Tank. The governing equations for solving incompressible fluid motion are Navier-Stokes equation and continuity equation, and the Marker-Density function technique is adopted to implement the fully-nonlinear free-surface kinematic condition. The marine environmental situations, i.e. waves, currents, wind, etc., are reproduced by use of multi-segmented wavemaker on the basis of the so-called "snake-principle". In this paper, some numerical reproduction techniques for regular and irregular waves, multi-directional waves, Bull's-eye wave, wave-current, and solitary wave are presented, and a model test in motion with large amplitude of roll angle is conducted in the developed 3D-NWT, using a overlaid grid system.

• International Journal of Ocean System Engineering
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• v.1 no.1
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• pp.37-45
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• 2011

The nonlinear free-surface motions interacting with a floating body were investigated using the Moving Particle Semi-implicit (MPS) method proposed by Koshizuka and Oka [6] for incompressible flow. In the numerical method, more realistic Lagrangian moving particles were used for solving the flow field instead of the Eulerian approach with a grid system. Therefore, the convection terms and time derivatives in the Navier-Stokes equation can be calculated more directly, without any numerical diffusion, instabilities, or topological failure. The MPS method was applied to a numerical simulation of predicting the efficiency of floating-type breakwater interacting with waves.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.585-586
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• 2023

본 논문에서는 바람의 이류(Advection)를 고려하여 사운드의 전파를 변형하는 방법을 제시한다. 사운드는 공기와 같은 매질의 진동을 통해 전파되는 파동이며, 이런 바람의 이동 방향은 사운드 에너지 전파에 직접적인 영향을 주며, 본 논문에서는 이를 광선추적법(Raytracing) 기반으로 모델링한다. 기존의 사운드 전파는 물리기반, 기하처리(Geometry processing), 혼합기법(Hybrid method) 등의 방법이 제안됐으며, 다양한 장면에서 좋은 결과를 만들어냈다. 하지만 바람의 움직임은 유체역학을 기반으로 한 나비에-스토크스 방정식(Navier-Stokes equation)에 의해 표현되기 때문에 사운드 전파만으로는 바람의 영향을 고려한 전파 형태를 모델링할 수 없다. 본 논문에서는 바람의 유동 중 이류를 고려하여 사운드 맵을 효율적으로 변형할 수 있는 방법을 제시한다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1989.11a
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• pp.94-99
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• 1989

This paper analyzes file stiffness, damping coefficient, friction force and flow coefficient of externally pressurized oil journal beating, including the effect of journal rotation according to the Sommerfeld number. This paper assumed that the oil in the whole pocket has constant pressure, and that the oil in the whole bearing region has constant viscosity, temperature and density. Reynolds equation is derived from Nuvier - Stokes equation and continuity equation. And solved bearing pressure by ADI method for whole bearing region and fitted with out flow rate of pocket region. The model for numerical simulation is hydro - static oil journal bearing for high-speed, high-accuracy lathe spindle.

• Communications of the Korean Mathematical Society
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• v.12 no.2
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• pp.467-478
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• 1997

A nonlinear Galerkin method for the Burgers equation is considered. Due to the lack of the divergence free condition, the nonlinear term is treated differently compared to that of the Navier-Stokes equations. Strong convergence results are proved for the nonlinear Galerkin method.

• KCID journal
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• v.3 no.1
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• pp.53-63
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• 1996

The hydraulic characteristics in constriction openings are analysed numerically by using Galerkin type finite element model of which the governing equation comprises the depth averaged continuous equation and the two-dimensional Navier-Stokes equation. Fo