• Title/Summary/Keyword: Chimera 격자계

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A Grid Adaptation Method Using the Chimera and Patched Grid Systems (중첩격자계와 접합격자계를 이용한 적응격자 기법)

  • Kim, De-Hee;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.10
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    • pp.17-25
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    • 2005
  • A grid adaptation method within systems of chimera and patched grids is presented. Problem domains are divided into near-body and off-body fields. Near-body field is filled with curvilinear body-fitted grids that extend only a short distance from body surfaces and connected to other grid systems via chimera domain connectivity method. Off-body field is filled with patched uniform cartesian grids of varying levels of refinement. This method gives flexibility in grid generation and efficient adaptation capability. Several numerical experiments including 2D store separation were performed to show the performance of the proposed adaptation method.

Development of Euler/Navier-Stokes Solver using Chimera Grid Method (Chimera 격자계를 이용한 Euler/Navier-Stokes Solver의 개발)

  • Lee S.;Park M.;Cho K. W.;Kwon J. H.
    • 한국전산유체공학회:학술대회논문집
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    • 1998.11a
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    • pp.141-146
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    • 1998
  • An Euler/Navier Stokes solver has been developed for the analysis of steady and unsteady flows. The $q-{\omega}$ turbulent model has been incorporated into the solver in strongly coupled manner for stability and robustness. A new Chimera hole cutting algorithm, Cut-paste algorithm, has been devised for automatic Chimera hole cutting. Number of viscous/inviscid numerical computations demonstrate the accuracy and the versatility of the solver.

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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.

Development of an Unstructured 2-D Chimera Technique for Overlapped Bodies in Relative Motion (2차원 비정렬 중첩격자계를 이용한 서로 겹쳐진 물체간의 상대운동 해석기법 개발)

  • An, Sang-Jun;Gwon, O-Jun;Jeong, Mun-Seung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.2
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    • pp.17-25
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    • 2006
  • In the present study, a 2-D chimera technique for overlapped bodies in relative motion is developed using unstructured triangular meshes. The solid boundary nodes located next to the intersecting point between bodies are merged to the intersecting point to assure accurate representation of the intersecting region. In order to assign proper value of flow variables at the nodes located out of the computational field, interpolation is conducted for non-active nodes. For validation, the motions of a NACA64A006 airfoil and a NACA0012 airfoil with a plane flap are computed and the results are compared with other simulations. The motion of a launching missile ejected from a NACA0012 airfoil is also simulated.

Development of a 2-dimensional Flow Solver using Hybrid Unstructured and Adaptive Cartesian Meshes (비정렬 및 적응 직교격자를 이용한 2차원 혼합격자계 유동해석 코드 개발)

  • Jung, M.K.;Kwon, O.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.294-301
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    • 2011
  • A two-dimensional hybrid flaw solver has been developed for the accurate and efficient simulation of steady and unsteady flaw fields. The flow solver was cast to accommodate two different topologies of computational meshes. Triangular meshes are adopted in the near-body region such that complex geometric configurations can be easily modeled, while adaptive Cartesian meshes are, utilized in the off-body region to resolve the flaw more accurately with less numerical dissipation by adopting a spatially high-order accurate scheme and solution-adaptive mesh refinement technique. A chimera mesh technique has been employed to link the two flow regimes adopting each mesh topology. Validations were made for the unsteady inviscid vol1ex convection am the unsteady turbulent flaws over an NACA0012 airfoil, and the results were compared with experimental and other computational results.

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Unsteady Separation Simulation of Missile by Using Moving Grid (움직이는 격자계를 이용한 유도탄의 비정상 분리 유동해석)

  • Kang, Kyoung-Tai;Lee, Bok-Jik;Ahn, Chang-Soo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.2
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    • pp.47-52
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    • 2007
  • Missile staging and airframe separation simulation were performed by using a numerical technique for simulating the dynamics of multiple moving bodies. A 6DOF model is fully integrated into the CFD solution procedure to determine the body dynamics. Chimera grid technique offered efficient CFD simulation of multiple moving bodies. Through this simulation the safety of deployed staging and airframe separation mechanism was verified.

Application of MSAP to JDAM Separation from an F/A-18C Aircraft (MSAP을 이용한 F/A-18C로 부터 JDAM 분리 해석)

  • Lee Seungsoo
    • Journal of computational fluids engineering
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    • v.9 no.1
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    • pp.41-47
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    • 2004
  • A successful store separation analysis tool, MSAP(Multi-body Separation Analysis Program) has been applied to F/A-18C/JDAM CFD Challenge Ⅱ. The challenge was devised to challenge CFD community to use CFD methodologies to predict and match the trajectory of a JDAM MK-84 separating from F/A-l8C. Trajectory simulations for two flight conditions were performed. Comparison between computed and measured flight trajectories for both conditions shows a good agreement.

Application of MSAP to JDAM Separation from an F/A-l8C Aircraft (MSAP을 이용한 F/A-l8C로부터 JDAM 분리 해석)

  • Lee Seungsoo
    • 한국전산유체공학회:학술대회논문집
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    • 2003.08a
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    • pp.89-94
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    • 2003
  • A successful store separation analysis tool, MSAP(Multi-body Separation Analysis Program) has been applied to F/A-18C/JDAM CFD Challenge II. The challenge was devised to challenge CFD community to use CFD methodologies to predict and match the trajectory of a JDAM MK-84 separating from F/A-l8C. Trajectory simulations for two flight conditions were performed. Comparison between computed and measured flight trajectories for both conditions shows a good agreement.

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A COMPUTATIONAL STUDY ABOUT BEHAVIOR OF AN UNDERWATER PROJECTILE USING A HOMOGENEOUS MIXTURE MODEL ON UNSTRUCTURED MESHES (비정렬 격자계에서 균질혼합 모델을 이용한 수중 운동체의 거동에 관한 수치적 연구)

  • Jo, S.M.;Choi, J.H.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.21 no.3
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    • pp.15-23
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    • 2016
  • In the present study, two phase flows around a projectile vertically launched from an underwater platform have been numerically investigated by using a three dimensional multi-phase RANS flow solver based on pseudo-compressibility and a homogeneous mixture model on unstructured meshes. The relative motion between the platform and projectile was described by six degrees of freedom equations of motion with Euler angles and a chimera technique. The propulsive power of the projectile was modeled as the fluid force acting on the lower surface of the body by the compressed air emitted from the underwater platform. Various flow conditions were considered to analyze the fluid-dynamics motion parameters of the projectile. The water level of platform and the current speed around the projectile were the main parametric variables. The numerical calculations were conducted up to 0.75sec in physical time scale. The dynamics tendency of the projectile was almost identical with respect to the water level variation due to the constant buoyancy term. The moving speed of the projectile along the vertical axis inside the platform decreased when the current speed increased. This is because the inflow from outside of the platform impeded development of the compressed air emitted from the floor surface of the launch platform. As a result, the fluid force acting on the lower surface of the projectile decreased, and injection time of the projectile from the platform was delayed.

A Study of Optimal Mesh Interface Region Generation to Improve Spatial and Temporal Accuracy (공간 및 시간 정확도 향상을 위한 최적의 삽간영역 구성에 관한 연구)

  • Cho Kum Won
    • Journal of computational fluids engineering
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    • v.8 no.3
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    • pp.41-49
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    • 2003
  • The spatial accuracy becomes first-order when second-order conservation schemes including the non-conservative interpolation in general Chimera method are used. To ensure the solution accuracy, the discontinuities must be located away from the overlapped regions, and the length of overlapped region also must be proportional to the grid spacing. In this paper, a proposed method, cut-paste algorithm, is used to satisfy above constraints. The cut-paste algorithm can generate the optimal mesh inteface region automatically, To validate the spatial and temporal accuracy due to the non-conservative interpolation, inviscid and viscous problems are tested.