• Title, Summary, Keyword: Unstructured meshes

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INTRODUCTION TO UNSTRUCTURED HYBRID MESH BASED FLOW SIMULATION TECHNIQUE (비정렬 혼합격자 기반 유동해석 기법 소개)

  • Ahn, H.T.
    • 한국전산유체공학회:학술대회논문집
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    • pp.112-115
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    • 2009
  • In this paper, flow simulation algorithms for utilizing unstructured hybrid meshes are introduced. First, various types of meshes are introduced. Advantages and disadvantages of each type of meshes are discussed. Unstructured hybrid mesh approach, that is best suited for high speed viscous flow simulation, is presented. Lastly, various types of flow simulations using unstructured hybrid meshes are introduced.

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Multi-dimensional Limiting Strategy for Robust, Accurate and Efficient Computations of Compressible Flows on Unstructured Meshes

  • Park, Jin-Seok;Yoon, Sung-Hwan;Kim, Chong-Am
    • 한국전산유체공학회:학술대회논문집
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    • pp.378-385
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    • 2008
  • The present paper deals with the accurate and robust limiting procedure for the multi-dimensional flow analysis on unstructured meshes. The multi-dimensional limiting process (MLP) which was successfully proposed on structured grid system is extended to unstructured meshes. Based on MUSCL-type framework on unstructured meshes, the new slope limiter is devised to satisfy the MLP condition, which is quite effective to regulate the unwanted oscillations, especially on multiple dimensions. Considering the neighborhood based on the vertex of the cell, as well as the edge, this limiting strategy captures the multi-dimensional flow features very accurately with the proper stencils. From the various numerical results, these desirable characteristics of the proposed limiting strategy are clearly shown.

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Multi-dimensional Limiting Strategy for Robust, Accurate and Efficient Computations of Compressible Flows on Unstructured Meshes

  • Park, Jin-Seok;Yoon, Sung-Hwan;Kim, Chon-Gam
    • 한국전산유체공학회:학술대회논문집
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    • pp.378-385
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    • 2008
  • The present paper deals with the accurate and robust limiting procedure for the multi-dimensional flow analysis on unstructured meshes. The multi-dimensional limiting process (MLP) which was successfully proposed on structured grid system is extended to unstructured meshes. Based on MUSCL-type framework on unstructured meshes, the new slope limiter is devised to satisfy the MLP condition, which is quite effective to regulate the unwanted oscillations, especially on multiple dimensions. Considering the neighborhood based on the vertex of the cell, as well as the edge, this limiting strategy captures the multi-dimensional flow features very accurately with the proper stencils. From the various numerical results, these desirable characteristics of the proposed limiting strategy are clearly shown.

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CONSERVATIVE OVERSET MESH TECHNIQUE ON 2-D UNSTRUCTURED MESHES (이차원 비정렬 격자계에서의 보존적 중첩 격자 기법)

  • Jung, M.S.;Kwon, O.J.;Kang, H.J.
    • 한국전산유체공학회:학술대회논문집
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    • pp.27-32
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    • 2008
  • In the present study, a conservative overset mesh technique has been developed on 2-D unstructured meshes. A new domain connection technique between independent mesh blocks was proposed to satisfy the conservation of mass, momentum, or energy in entire computational domain. The present technique was applied to several classical computational problems to validate the superiority of the conservative method to the non-conservative method.

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CONSERVATIVE OVERSET MESH TECHNIQUE ON 2-D UNSTRUCTURED MESHES (이차원 비정렬 격자계에서의 보존적 중첩 격자 기법)

  • Jung, M.S.;Kwon, O.J.;Kang, H.J.
    • 한국전산유체공학회:학술대회논문집
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    • pp.27-32
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    • 2008
  • In the present study, a conservative overset mesh technique has been developed on 2-D unstructured meshes. A new domain connection technique between independent mesh blocks was proposed to satisfy the conservation of mass, momentum, or energy in entire computational domain. The present technique was applied to several classical computational problems to validate the superiority of the conservative method to the non-conservative method.

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DEVELOPMENT OF IMPLICIT DISCONTINUOUS GALERKIN METHOD ON UNSTRUCTURED MESHES (비정렬 격자계에서 내재적 불연속 갤러킨 기법의 개발)

  • Lee, H.D.;Kwon, O.J.
    • 한국전산유체공학회:학술대회논문집
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    • pp.30-40
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    • 2007
  • The implicit discontinuous Galerkin method for the two-dimensional Euler equations was developed on unstructured triangular meshes, which can achieve higher-order accuracy by wing hierachical basis functions based on Legendre polynomials. Numerical tests were conducted to estimate the convergence order of numerical solutions to the Ringleb flow and the supersonic vortex flow for which analytic solutions are available. And, the flows around a circle and a NACA0012 airfoil was also numerically simulated. Numerical results show that the implicit discontinuous Galerkin methods with higher-order representation of curved solid boundaries can be an efficient higher-order method to obtain very accurate numerical solutions on unstructured meshes.

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Parallel 3-D Aerodynamic Shape Optimization on Unstructured Meshes

  • Lee, Sang-Wook;Kwon, Oh-Joon
    • International Journal of Aeronautical and Space Sciences
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    • v.4 no.1
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    • pp.45-52
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    • 2003
  • A three-dimensional aerodynamic shape optimization technique in inviscid compressible flows is developed by using a parallel continuous adjoint formulation on unstructured meshes. A new surface mesh modification method is proposed to overcome difficulties related to patch-level remeshing for unstructured meshes, and the effect of design sections on aerodynamic shape optimization is examined. Applications are made to three-dimensional wave drag minimization problems including an ONERA M6 wing and the EGLIN wing-pylon-store configuration. The results show that the present method is robust and highly efficient for the shape optimization of aerodynamic configurations, independent of the number of design variables used.

DEVELOPMENT OF AN HIGH-ORDER IMPLICIT DISCONTINUOUS GALERKIN METHOD ON UNSTRUCTURED MESHES (비정렬 격자계에서 고차 정확도의 내재적 불연속 갤러킨 기법의 개발)

  • Lee, H.D.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.12 no.3
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    • pp.29-40
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    • 2007
  • An implicit discontinuous Galerkin method for the two-dimensional Euler equations was developed on unstructured triangular meshes. The method can achieve high-order spatial accuracy by using hierachical basis functions based on Legendre polynomials. Numerical tests were conducted to estimate the convergence order of numerical solutions to the Ringleb flow and the supersonic vortex flow for which analytic solutions are available. Also, the flows around a 2-D circular cylinder and an NACA0012 airfoil were numerically simulated. The numerical results showed that the implicit discontinuous Galerkin methods couples with a high-order representation of curved solid boundaries can be an efficient method to obtain very accurate numerical solutions on unstructured meshes.

Calculation of Turbulent Flows Using an Implicit Scheme on Two-Dimensional Unstructured Meshes (2차원 비정렬 격자에서의 내재적 기법을 이용한 난류 유동 재산)

  • Kang Hee Jung;Kwon Oh Joon
    • Journal of computational fluids engineering
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    • v.2 no.2
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    • pp.26-34
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    • 1997
  • An implicit viscous turbulent flow solver is developed for two-dimensional geon unstructured triangular meshes. The flux terms are discretized based on a cell-centered formulation with the Roe's flux-difference splitting. The solution is advanced in time us backward-Euler time-stepping scheme. At each time step, the linear system of equation approximately solved wi th the Gauss-Seidel relaxation scheme. The effect of turbulence is with a standard k-ε two-equation model which is solved separately from the mean flow equation the same backward-Euler time integration scheme. The triangular meshes are generated advancing-front/layer technique. Validations are made for flows over the NACA 0012 airfoil. Douglas 3-element airfoil. Good agreements are obtained between the numerical result experiment.

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