• Title, Summary, Keyword: 비정렬격자

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비정렬격자 모델에 기반한 콜럼비아 강에서의 유출유 모델링

  • Jeong, Yeon-Cheol
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.222-224
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    • 2011
  • 본 연구에서는 유한체적법과 함께 비정렬 격자(Unstructured Grid) 를 채택한 SELFE 모델을 기반으로 운영되는 유출유 확산모델을 개발하였다. 모델의 적용성을 검토하기 위해 미극 오레건주 콜롬비아 강의 유출유 모델링에 적용하였으며 양호한 결과를 얻을 수 있었다. 앞으로 이 모델은 하천, 호수 및 해양을 포함한 다양한 수계에 적용이 가능할 것으로 기대된다.

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Development of a Parallel Cell-Based DSMC Method Using Unstructured Meshes (비정렬격자에서 병렬화된 격자중심 직접모사 기법 개발)

  • Kim, Hyeong-Sun;Kim, Min-Gyu;Gwon, O-Jun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.2
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    • pp.1-11
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    • 2002
  • In the present study, a parallel DSCM technique based on a cell-based data structure is developed for the efficient simulation of rarefied gas flows especially od PC clusters. Dynamic load balancing is archieved by decomposing the computational domain into several sub-domains and accounting for the number of particles and the number cells of each domain. Mesh adaptation algorithm is also applied to improve the resolution of the solution and to reduce the grid dependency. It was demonstrated that accurate solutions can be obtained after several levels of mesh adapation starting from a coars initial grid. The method was applied to a two-dimensioanal supersonic leading-edge flow and the axi-symmetric Rothe nozzle flow to validate the efficiency of the present method. It was found that the present method is a very effective tool for the efficient simulation of rarefied gas flow on PC-based parallel machines.

Unstructured Pressure Based Method for All Speed Flows (전 속도영역 유동을 위한 비정렬격자 압력기반해법)

  • Choi, Hyung-Il;Lee, Do-Hyung;Maeng, Joo-Sung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.11
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    • pp.1521-1530
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    • 2002
  • This article proposes a pressure based method for predicting flows at all speeds. The compressible SIMPLE algorithm is extended to unstructured grid framework. Convection terms are discretized using second-order scheme with deferred correction approach. Diffusion term discretization is based on structured grid analogy that can be easily adopted to hybrid unstructured grid solver. This method also uses node centered scheme with edge based data structure for memory and computing time efficiency of arbitrary grid types. Both incompressible and compressible benchmark problems are solved using the above methodology. The demonstration of this method is extended to slip flow problem that has low Reynolds number but compressibility effect. It is shown that the proposed method can improve efficiency in memory usage and computing time without losing any accuracy.

An Unstructured 3-D Chimera Technique for Overlapped Bodies inRelative Motion (3차원 비정렬 중첩격자계를 이용한 서로 겹쳐진 물체들 간의 상대운동 해석기법에 관한 연구)

  • 안상준;권오준;정문승
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.8
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    • pp.1-7
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    • 2006
  • In the present study, A 3-D chimera technique for overlapped bodies in relative motion is studied using unstructured meshes. If all node points of a mesh element at solid boundary are in another body, this element is excluded from computational domain. For computation of unsteady flow, non-active cells have proper variables using interpolation and extrapolation. These variables are used in next time step. The motion of a launching trajectory ejected from a wing and the motion of deploying fins of a trajectory which have not been simulated are computed to conform practicality of this technique.

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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A Locally Linear Reconstruction scheme on arbitrary unstructured meshes (임의의 비정렬 격자계에서의 국지적 선형 재구성 기법)

  • Lee K. S.;Baek J. H.
    • 한국전산유체공학회:학술대회논문집
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    • pp.31-36
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    • 2003
  • A field reconstruction scheme for a cell centered finite volume method on unstructured meshes is developed. Regardless of mesh quality, this method is exact within a machine accuracy if the solution is linear, which means it has full second order accuracy. It does not have any limitation on cell shape except convexity of the cells and recovers standard discretization stencils at structured orthogonal grids. Accuracy comparisons with other popular reconstruction schemes are performed on a simple example.

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NUMERICAL METHOD FOR THE TWO-FLUID THREE-FIELD MODEL ON AN UNSTRUCTURED MESH (비정렬격자 2-유체 3-상 유동 해석 기법)

  • Kim, J.;Park, I.K.;Cho, H.K.;Yoon, H.Y.;Jeong, J.J.
    • 한국전산유체공학회:학술대회논문집
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    • pp.243-248
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    • 2007
  • A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.

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NUMERICAL METHOD FOR TWO-PHASE FLOW ANALYSIS USING SIMPLE-ALGORITHM ON AN UNSTRUCTURED MESH (비정렬격자 SIMPLE 알고리즘기반 이상유동 수치해석 기법)

  • Kim, Jong-Tae;Park, Ik-Kyu;Cho, Hyung-Kyu;Kim, Kyung Doo;Jeong, Jae-Jun
    • Journal of computational fluids engineering
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    • v.13 no.4
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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.