• Title/Summary/Keyword: 적응 직교격자

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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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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 A 2-D UNSTEADY FLOW SIMULATION CODE USING CARTESIAN MESHES (직교격자를 이용한 2차원 비정상 유동해석 코드 개발)

  • Jung, Min-Kyu;Lee, Jae-Eun;Park, Se-Youn;Kwon, Oh-Joon;Kwon, Jang-Hyuk;Shin, Ha-Yong
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.116-120
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    • 2009
  • A two-dimensional unsteady inviscid flow solver has been developed for the simulation of complex geometric configurations on adaptive Cartesian meshes. Embedded condition was used for boundary condition and a predictor-corrector explicit time marching scheme was used for time-accurate numerical simulation. The Cartesian mesh generator, which was previously developed for steady problem, was used grid generation for unsteady flow. The solver was based on ALE formulation for body motion. For diminishing the effects of cut-cells, the cell merging method was used. Using cell merging method, it was eliminated the CFL constraints. The conservation problem, which is caused cell-type variation around region swept by solid boundary, was also solved using cell merging method. The results are presented for 2D circular cylinder and missile launching problem.

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Wiener-Hopf Equation with Robustness to Application System (응용시스템에 강건한 Wiener-Hopf 방정식)

  • Cho, Ju-Phil;Lee, Il-Kyu;Cha, Jae-Sang
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.11 no.4
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    • pp.245-249
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    • 2011
  • In this paper, we propose an equivalent Wiener-Hopf equation. The proposed algorithm can obtain the weight vector of a TDL(tapped-delay-line) filter and the error simultaneously if the inputs are orthogonal to each other. The equivalent Wiener-Hopf equation was analyzed theoretically based on the MMSE(minimum mean square error) method. The results present that the proposed algorithm is equivalent to original Wiener-Hopf equation. In conclusion, our method can find the coefficient of the TDL (tapped-delay-line) filter where a lattice filter is used, and also when the process of Gram-Schmidt orthogonalization is used. Furthermore, a new cost function is suggested which may facilitate research in the adaptive signal processing area.

Development of a Cartesian-based Code for Effective Simulation of Flow Around a Marine Structure - Integration of AMR, VOF, IBM, VIV, LES (효율적인 해양구조물 유동 해석을 위한 직교좌표계 기반의 코드 개발 - AMR, VOF, IBM, VIV, LES의 통합)

  • Lee, Kyongjun;Yang, Kyung-Soo
    • Journal of the Society of Naval Architects of Korea
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    • v.51 no.5
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    • pp.409-418
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    • 2014
  • Simulation of flow past a complex marine structure requires a fine resolution in the vicinity of the structure, whereas a coarse resolution is enough far away from it. Therefore, a lot of grid cells may be wasted, when a simple Cartesian grid system is used for an Immersed Boundary Method (IBM). To alleviate this problems while maintaining the Cartesian frame work, we adopted an Adaptive Mesh Refinement (AMR) scheme where the grid system dynamically and locally refines as needed. In this study, We implemented a moving IBM and an AMR technique in our basic 3D incompressible Navier-Stokes solver. A Volume Of Fluid (VOF) method was used to effectively treat the free surface, and a recently developed Lagrangian Dynamic Subgrid-scale Model (LDSM) was incorporated in the code for accurate turbulence modeling. To capture vortex induced vibration accurately, the equation for the structure movement and the governing equations for fluid flow were solved at the same time implicitly. Also, We have developed an interface by using AutoLISP, which can properly distribute marker particles for IBM, compute the geometrical information of the object, and transfer it to the solver for the main simulation. To verify our numerical methodology, our results were compared with other authors' numerical and experimental results for the benchmark problems, revealing excellent agreement. Using the verified code, we investigated the following cases. (1) simulating flow around a floating sphere. (2) simulating flow past a marine structure.