• 한국해양공학회지
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• 제27권2호
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• pp.39-46
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• 2013

In this study, the impact loads on tank walls by sloshing phenomena and on a tall structure in a three-dimensional rectangular tank were predicted using multiphase flow simulations. The solver was based on the CIP/CCUP (Constraint interpolation CIP/CIP combined unified procedure) method, and the THINC-WLIC (Tangent hyperbola for interface capturing-weighted line interface calculation) scheme was used to capture the air-water interface. For the convection terms of the Navier-Stokes equations, the USCIP (Unsplit semi-lagrangian CIP) method was adopted. The results of simulations were compared with those of experiments. Overall, the comparisons were reasonably good.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1215-1220
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• 2008

To obtain the shape of the free surface more accurately, computations are carried out by a finite volume method using unstructured meshes and an interface capturing method. Free-surface flow, which is very important in the fields of ship and marine engineering, is numerically simulated for flows of both water and air. Control volumes are used with an arbitrary number of faces and allows a local mesh refinement. The integration is of second order, with a midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation. The solution method of pressure-correction type solves sequentially equations of momentum, continuity, conservation, and two-equations turbulence model. Comparison are quantitatively made between the computation and experiment in order to confirm the solution method.

• 한국전산유체공학회지
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• 제16권2호
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• pp.1-10
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• 2011

A new computational program, which is based on the CIP/CCUP(Constraint Interpolation Profile/CIP Combined Unified Procedure) method, has been developed to numerically analyse sloshing phenomena dealt as multiphase-flow problems. For the convection terms of Navier-Stokes equations, the RCIP(Rational function CIP) method was adopted and the THINC-WLIC(Tangent of Hyperbola for Interface Capturing-Weighted Line Interface Calculation) method was used to capture the air/water interface. To validate the present numerical method, two-dimensional dam-breaking and sloshing problems in a rectangular tank were solved by the developed method in a stationary Cartesian grid system. In the case of sloshing problems, simulations by using a improved MPS(Moving Particle Simulation) method, which is named as PNU-MPS(Pusan National University-MPS), were also carried out. The computational results are compared with those of experiments and most of the comparisons are reasonably good.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 추계 학술대회논문집
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• pp.103-108
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• 2002

The M-AUSMPW+ scheme that can capture shock waves exactly with monotonic characteristics is modifided from AUSMPW+ by analyzing the cause of oscillation in shock regions. Firstly shock-capturing characteristics of general FVS including the AUSM-type schemes are investigated in detail, according to the difference between a cell-interface and a sonic transition position. The cause of oscillation is the improper numerical dissipation that could not represent the real Physics. The M-AUSMPW+ could capture shocks exactly without oscillatory behaviors in considering the sonic transition position and an cell-interface position.

• International Journal of Ocean System Engineering
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• 제1권3호
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• pp.136-143
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• 2011

In this paper, three-dimensional free-surface flows are simulated by using two different numerical methods, the constrained interpolation profile (CIP)-based and finite volume (FV)-based methods. In the CIP-based method, the governing equations are solved on stationary staggered Cartesian grids by a finite difference method, and an immersed boundary technique is applied to deal with wave-body interactions. In the FV-based method, the governing equations are solved by applying collocated finite volume discretization, and body-fitted meshes are used. A free-surface boundary is considered as the interface of the multi-phase flow with air and water, and a volumeof-fluid (VOF) approach is applied to trace the free surface. Among many variations of the VOF-type method, the tangent of hyperbola for interface capturing (THINC) and the compressive interface capturing scheme for arbitrary meshes (CICSAM) techniques are used in the CIP-based method and FV-based method, respectively. Numerical simulations have been carried out for dam-breaking and wave-body interaction problems. The computational results of the two methods are compared with experimental data and their differences are observed.

• 대한조선학회논문집
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• 제47권3호
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• pp.279-290
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• 2010

In this paper, a VOF method called RHRIC (refined high resolution intertace capturing) is introduced for solving the motion of the free surface and applied to the simulation of the advection of rigid interiaces of different shapes and a 20 dam-break problem, which are typical benchmark test cases. The numerical results for the interface advection cases are compared to the analytic solutions, while the available experimental data and other numerical results of various free surface methods for the dam-break problem are provided for the validation of the proposed VOF method. The same simulations were also carried out using the original HRIC scheme and a modified HRIC scheme called MHRIC for comparison. Although the RHRIC uses a simple order scheme, a basis of the original HRIC scheme, lower than the third-order ULTIMATE-QUICKEST used by the MHRIC, it provides an improved accuracy over the two previous HRIC methods.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.2-5
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• 2011

This paper presents a numerical study on multiphase flows induced by wall adhesion The CSF(Continuum Surface Force} model is used for the calculation of the surface tension force and implemented in an in-house solution code(PowerCFD). The present method(code) employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with volume capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing As an application of the present method, the effects of wall adhesion are numerically simulated with the CSF model for a shallow pool of water located at the bottom of a cylindrical tank. Two different cases are computed, one in which the water wets the wall and one in which the water does not wet the wall. It is found that the present method simulates efficiently and accurately surface tension-dominant multiphase flows induced by wall adhesion.

• 대한기계학회논문집B
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• 제38권6호
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• pp.513-523
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• 2014

유체이송 기술은 최근 마이크로 유체시스템 개발에서 핵심문제로 인식되고 있다. 본 연구에서는 최근 저자가 제안한 외부동력을 사용하지 않고 액적을 이송시킬 수 있는 새로운 개념인 친수성/소수성 수평 표면에서의 액적이송을 자체개발 코드(PowerCFD)를 사용하여 수치해석하였다. 수치해석에 사용된 코드는 보존적인 압력기반 유한체적방법에 기초한 비정렬 셀 중심 방법 및 VOF 방법에 체적포착법인 CICSAM을 채용하고 있다. 액적 내 및 주위의 속도벡터, 압력분포 및 전체운동에너지와 같은 수치해석 결과를 제시하고 이 결과들을 통해 액적이송 메커니즘을 규명하였다.

• 대한기계학회논문집B
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• 제39권4호
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• pp.359-370
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• 2015

본 연구는 다양한 조건하에서 모세관력 불균형에 의해 구동되는 수평 표면 위의 액적 거동을 수치해석적으로 연구한 것이다. 액적 거동은 자체개발 코드(PowerCFD)를 사용하여 수치해석하였다. 수치해석에 사용된 코드는 보존적인 압력기반 유한체적방법에 기초한 비정렬 셀 중심 방법 및 VOF 방법에 체적포착법인 CICSAM을 채용하고 있다. 상세한 액적 거동이 다양한 초기 액적형상, 접촉각 및 표면장력(또는 Bond 수)의 조건하에서 얻어졌다. 또한 액적 이송 메커니즘이 액적 형상에 대한 수치해석 결과로부터 검토되었다.

• 대한기계학회논문집B
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• 제38권3호
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• pp.263-270
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• 2014

유체이송 기술은 최근 마이크로 유체시스템 개발에서 핵심문제로 인식되고 있다. 본 논문에서는 외부동력을 사용하지 않고 액적을 이송시킬 수 있는 새로운 개념을 제안하고, 수치해석을 통해 증명하였다. 제안된 장치는 표면을 단순하게 친수성과 소수성 표면의 복합표면으로 구성하는 것이다. 새로운 개념을 입증하기 위한 수치해석은 보존적인 압력기반 유한체적방법에 기초한 비정렬 셀 중심 방법 및 VOF 방법에 체적포착법인 CICSAM을 채용하고 있는 자체개발 코드(PowerCFD)를 사용하였다. 연구결과 본 연구에서 제안된 개념이 마이크로 유체시스템에서 액적이송에 대해 우수한 성능을 나타내는 것으로 확인되었다.