• 한국전산유체공학회지
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• 제13권4호
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• pp.86-95
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• 2008

For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1349-1353
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• 2003

CEMTool is a command style design and analyzing package for scientific and technological algorithm and a matrix based computation language. In this paper, we present a compiler based approach to the implementation of the command mode generalized PDE solver in CEMTool. In contrast to the existing MATLAB PDE Toolbox, our proposed FEM package can deal with the combination of the reserved words such as "laplace" and "convect". Also, we can assign the border lines and the boundary conditions in a very easy way. With the introduction of the lexical analyzer and the parser, our FEM toolbox can handle the general boundary condition and the various PDEs represented by the combination of equations. That is why we need not classify PDE as elliptic, hyperbolic, parabolic equations. Consequently, with our new FEM toolbox, we can overcome some disadvantages of the existing MATLAB PDE Toolbox.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.71-78
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• 2008

For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.71-78
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• 2008

For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.43-48
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• 1998

The development of unsteady three-dimensional incompressible viscous solver based on unsteady physical curvilinear coordinate system is presented. A 12-point finite analytic scheme based on local uniform grid spacing is extended for nonuniform grid spacing. The formulation of a condition is suggested to avoid the oscillation of the series summations produced by the application of the method of separation of variables. SIMPLER and pressure Poisson equation techniques are used for solving a velocity-pressure coupled problem. The matrix is solved using the Generalized Minimal RESidual (GMRES) method to enhance the convergence rate of unsteady flow solver and the Kinematic boundary condition of a free surface flow. It is demonstrated that the numerical solutions of these equations are less mesh sensitive.

• 설비공학논문집
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• 제11권3호
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• pp.281-291
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• 1999

A computer code based on a node equation method has been developed for the analysis of pipe network. Both data structure and object-oriented programming technique are used for pipe and node modelling, in which simplification process is applied to complicated and large pipe network. The semi-direct solver, ILU-CGS, improves greatly both the accuracy and the rate of convergence. The computational result of high-pressure pipe network of city gas in Taegu shows the good agreement with the real data.

• 한국전산유체공학회지
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• 제3권1호
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• pp.22-29
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• 1998

Parallel implementation is conducted for a SIMPLER finite volume model. The present parallelism is based on domain decomposition and explicit message passing using MPI and SHMEM. Two parallel solvers to tridiagonal matrix equation are employed. The implementation is verified on the Cray T3E system for a benchmark problem of natural convection in a sidewall-heated cavity. The test results illustrate good scalability of the present parallel models. Performance issues are elaborated in view of convergence as well as conventional parallel overheads and single processor performance. The effectiveness of a localized matrix solution algorithm is demonstrated.

• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.125-138
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• 2001

An efficient correction storage scheme on a structured grid is applied to a sequence of approximate Jacobian systems arising at each time step from a linearization of the discrete nonlenear system of equations, obtained by the implicit time discretization of the conservation laws for unsteady fluid flows. The contribution of freezing the Jacobian matrix to computing costs is investigated within the correction storage scheme. The performance of the procedure is exhibited by measuring CPU time required to obtain a fully developed laminar vortex shedding flow past a circular cylinder, and is compared with that of a collective iterative method on a single grid. In addition, some computed results of the flow are presented in terms of some functionals along with measured data. The computational test shows that the computing costs may be saved in favor of the correction storage scheme with the frozen Jacobian matrix, to a great extent.

• 한국전산구조공학회논문집
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• 제29권1호
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• pp.61-65
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• 2016

복합재는 높은 비강도와 비강성을 가지고 있어 자동차, 항공기 등 전반적인 산업분야에서 널리 사용되는 재료이다. 우주선의 노즐 부분과 같이 높은 온도뿐만 아니라 높은 압력이 작용하는 환경에서 사용하기 위한 재료로 복합재가 필요하다. 복합재의 물성치를 아는 것은 매우 중요한데 모재(matrix)와 강화섬유(fiber) 각각의 물성치를 수치적으로 대입해 얻는 결과는 실험값과의 오차가 커 예측하는데 있어 더 정확한 방법이 필요할 것이다. 본 연구에서는 유한요소법을 이용한 EDISON용 CASAD solver 프로그램을 활용해 분석하였다. matrix와 fiber의 물성치를 대입해 복합재의 물성치를 구해 실험으로 측정된 물성치, 경험식으로 계산된 물성치와 비교를 하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.545-560
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• 2008

O Source import ㅁDirect import form Nastran, ANSYS ㅁDirect import of all the RPM from the files containing the structural results O Solver ㅁDirect computation of all RPM (multiple load case): one matrix resolution with multiple RHS ㅁEfficient solvers (MUMPS, SPARSE, Iterative) ㅁFrequency parallelisms available for very large problems O In practice ㅁSmall problems run on a desktop ㅁLarge problems can exceed 3kHz on a car engine O Easy to mesh ㅁ3D model created in a few minutes thanks to the unequal meshes. O And all Actran standard features