• 제목/요약/키워드: 자유표면 포착

검색결과 14건 처리시간 0.028초

유한체적법에 의한 이층류 계산 및 쇄파에 관한 토의 (Computation of Two-Fluid Flows by Finite Volume Method and Discussion on Wave Breaking)

  • Milovan Peric
    • 한국해양공학회지
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    • 제14권1호
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    • pp.11-16
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    • 2000
  • 수중날개를 대상으로 임의로 변형하는 이층류의 수직계산을 수행하였다. 계산은 비구조격자와 접면포착법을 이용하여 자유표면의 형상을 결정하였다 본 연구에 의하면 낮은 물속 깊이와 높은 프루드수에서 쇄파현상이 발생하였다 수중날개에 대하여 쇄파형상의 효과를 연구하였고 실험값과 계산값을 상호비교함으로서 격자의 민감성을 수직적으로 확인하였다.

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비정렬격자계와 체적포착법을 사용한 표면장력이 지배적인 다상유동 수치해석 (Numerical Simulation of Surface Tension-Dominant Multiphase Flows by Using Volume-Capturing Method and Unstructured Grid System)

  • 명현국
    • 대한기계학회논문집B
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    • 제35권7호
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    • pp.723-733
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    • 2011
  • 본 연구에서는 비정렬격자계와 체적포착법을 사용하여 표면장력이 지배적인 다상유동의 수치해석 방법을 제시하였다. 먼저 표면장력에 대한 CSF(Continuum Surface Force) 모델을 비정렬격자계에 적용할 수 있도록 수치해석 방법을 확립시켜 Myong(2009)이 개발한 비정렬격자계와 체적포착법을 사용한 수치 해석코드에 삽입하였다. 테스트 문제로 오직 표면장력만이 존재하는 평형상태의 정적(static) 액적 및 비평형상태의 동적(dynamic) 액적 문제에 적용하여, 이 해석방법의 유용성과 정확도를 평가하였다. 연구결과, 매끄러운 곡률 계산을 위해 필요한 필터로 본 연구에서 제안한 Laplacian 필터와 함께 CSF 모델로는 밀도보정(density-scaled)한 CSF 모델이 예측성능이 우수한 것으로 나타났다. 또한 표면장력 계산을 위한 이 모델을 채용한 본 수치해석방법은 표면장력이 지배적인 다상유동인 평형상태의 정적 액적 및 비평형상태의 동적 액적 문제 모두에 대해 정확성과 유용성이 입증되었다.

자유표면유동 해석을 위한 비정렬격자계에 적합한 경계면포착법 연구 (A STUDY ON AN INTERFACE CAPTURING METHOD APPLICABLE TO UNSTRUCTURED MESHES FOR THE ANALYSIS OF FREE SURFACE FLOW)

  • 명현국;김종은
    • 한국전산유체공학회지
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    • 제11권4호
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    • pp.14-19
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    • 2006
  • A conservative finite-volume method for computing 3-D flow with an unstructured cell-centered method has been extended to free surface flows or two-fluid systems with topologically complex interfaces. It is accomplished by implementing the high resolution method(CICSAM) by Ubbink(1997) for the accurate capturing of fluid interfaces on unstructured meshes, which is based on the finite-volume technique and is fully conservative. The calculated results with the present method are compared to show the ease and accuracy with available numerical and experimental results reported in the literature.

다상유동 해석을 위한 비정렬격자계를 사용한 체적포착법 (VOLUME CAPTURING METHOD USING UNSTRUCTURED GRID SYSTEM FOR NUMERICAL ANALYSIS OF MULTIPHASE FLOWS)

  • 명현국
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2009년 추계학술대회논문집
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    • pp.201-210
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    • 2009
  • A volume capturing method using unstructured grid system for numerical analysis of multiphase flows is introduced in the present paper. This method uses an interface capturing method (CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The novelty of CICSAM lies in the adaptive combination of high resolution discretization scheme which ensures the preservation of the sharpness and shape of the interface while retaining boundedness of the field, and no explicit interface reconstruction which is perceived to be difficult to implement on unstructured grid system. Several typical test cases for multiphase flows are presented, which are simulated by an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with CICSAM. It is found that the present method simulates efficiently and accurately complex free surface flows such as multiphase flows.

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경계면 포착법에 의한 밀도차이에 따른 물질경계면을 갖는 다상유동 수치해석 (Numerical Simulation of Multiphase Flows with Material Interface due to Density Difference by Interface Capturing Method)

  • 명현국
    • 대한기계학회논문집B
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    • 제33권6호
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    • pp.443-453
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    • 2009
  • The Rayleigh-Taylor instability, the bubble rising in both partially and fully filled containers and the droplet splash are simulated by an in-house solution code(PowerCFD), which are typical benchmark problems among multiphase flows with material interface due to density difference. The present method(code) employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The present results are compared with other numerical solutions found in the literature. It is found that the present method simulates efficiently and accurately complex free surface flows such as multiphase flows with material interface due to both density difference and instability.

비정렬격자계에 적합한 경계면포착법에서의 HR 도식 비교연구 (Comparative Study on High Resolution Schemes in Interface Capturing Method Suitable for Unstructured Meshes)

  • 명현국
    • 대한기계학회논문집B
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    • 제32권1호
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    • pp.23-29
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    • 2008
  • Two high resolution compressive schemes, CICSAM(Ubbink, 1997) and HRIC(Muzaferija & Peric, 1999), in interface capturing method are reviewed briefly with respect to the extended forms suitable for unstructured meshes. And then those are applied to three typical test cases of translation test, shearing flow test and collapsing water problem with an obstacle. It is accomplished by implementing the high resolution schemes in the in-house CFD code(PowerCFD) for computing 3-D flow with an unstructured cell-centered method, which is based on the finite-volume technique and fully conservative. The calculated results show that CICSAM is better than HRIC with respect to accuracy and robustness, although either scheme can be used as a good choice for free surface or two-phase flow simulation.

경계면 포착법을 사용한 밀도차에 따른 다상유동에 관한 수치해석적 연구 (NUMERICAL STUDY ON TWO-DIMENSIONAL MULTIPHASE FLOWS DUE TO DENSITY DIFFERENCE WITH INTERFACE CAPTURING METHOD)

  • 명현국
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2007년도 추계 학술대회논문집
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    • pp.214-219
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    • 2007
  • Both the bubble rising in a fully filled container and the droplet splash are simulated by a solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method (CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The present results are compared with other numerical solutions found in the literature. It is found that the present code simulate complex free surface flows such as multi phase flows due to large density difference efficiently and accurately.

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경계면포착법에 의한 밀도차에 따른 다상유동 수치해석 (Numerical Simulation of Two-Dimensional Multiphase Flows due to Density Difference by Interface Capturing Method)

  • 명현국
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2008년도 춘계학술대회논문집
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    • pp.572-575
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    • 2008
  • Two-dimensional multiphase flows due to density difference such as the Rayleigh-Taylor instability problem and the droplet splash are simulated by an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method in a volume of fluid(VOF) scheme for phase interface capturing. The present results are compared with other numerical solutions found in the literature. It is found that the present code simulates complex free surface flows such as multiphase flows due to density difference efficiently and accurately.

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벽면부착에 의해 야기되는 다상유동에 관한 수치적 연구 (Numerical Study on Multiphase Flows Induced by Wall Adhesion)

  • 명현국
    • 대한기계학회논문집B
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    • 제36권7호
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    • pp.721-730
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    • 2012
  • 본 연구에서는 벽면부착에 의해 야기되는 다상유동에 대한 수치적 연구를 제시한다. 먼저 다상유동 해석을 위해 표면장력에 대한 CSF(Continuum Surface Force) 모델 및 벽면부착 경계조건 모델을 비정렬격자계에 적합하도록 수치해석방법을 정립시키고, Myong(2009)이 개발한 비정렬격자계와 VOF 방법으로 체적포착법(volume capturing method)을 사용한 수치해석방법(코드)에 삽입하였다. 또한 본 수치해석방법을 사용하여 중력을 포함하여 어떤 외력도 존재하지 않고 오직 벽면부착에 의해 야기되는 유동현상인 원통형 탱크의 바닥에 위치한 얕은 물풀(water pool)에 대해 물이 벽면을 적시는 경우와 적시지 않는 경우에 대해 수치해석 하였다. 연구결과, 본 수치해석방법은 벽면부착에 의해 야기되는 다상유동 문제에 대한 유용성이 입증되었다.

접면포착법에 의한 수중익 주위의 이층류 유동계산 (Computation of Two-Fluid Flows with Submerged hydrofoil by Interface Capturing Method)

  • 곽승현
    • 한국항만학회지
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    • 제13권1호
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    • pp.167-174
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    • 1999
  • Numerical analysis of two-fluid flows for both water and air is carried out. Free-Surface flows with an arbitrary deformation have been simulated around two dimensional submerged hydrofoil. The computation is performed using a finite volume method with unstructured meshes and an interface capturing scheme to determine the shape of the free surface. The method uses control volumes with an arbitrary number of faces and allows cell-wise local mesh refinement. the integration in space is of second order based on midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation in time through three time levels The linear equation systems are solved by conjugate gradient type solvers and the non-linearity of equations is accounted for through picard iterations. The solution method is of pressure-correction type and solves sequentially the linearized momentum equations the continuity equation the conservation equation of one species and the equations or two turbulence quantities.

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