• 제목/요약/키워드: 캐버티 유동

검색결과 11건 처리시간 0.02초

외부유동에 의한 캐버티 내의 비정상 유동특성 (Unsteady Flow in a Cavity Induced by An Oscillatory External Flow)

  • 서용권;박준관;문종춘
    • 한국해양공학회지
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    • 제10권3호
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    • pp.105-116
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    • 1996
  • In this paper, we report the experimental results for the flow pattern and the material transport around a cavity subject to a sinusoidal external flow at the far region to ward the open side of the cavity. A tilting mechanism is used to generate a oscillatory flow inside a shallow rectangular container having a cavity at one side. The surface flow visualization is performed to obtain the unsteady behavior of vortices generated at two edges situated at the entrance of the cavity. It was found that at the period 4.5 sec., the behavior of the vortices is asymmetric, and there exists a steady residual flow in the cavity. The bottom flow patterns are also visualized. There are two regions outside of the cavity where the bottom fluid particles concentrate. The material transport in this flow model is very peculiar; fluid particles in the cavity flows outward through the passage along the walls starting from the edges, and particles in the outer region approach the cavity from the central region.

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액체의 표면 특성을 고려한 3차원 캐버티 내부의 스톡스 유동 특성 연구 (Study on the Stokes' Flow within a Three-Dimensional Cavity Considering Surface Characteristics)

  • 허효원;정원혁;서용권
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2011년 춘계학술대회논문집
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    • pp.382-386
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    • 2011
  • In this study, a CFD code is developed to perform simulation of the surface and internal flow of a three-dimensional rectangular cavity driven by an external gas flow. Investigated in this study are surface characteristic such as surface tension, surface dilational viscosity(or surface elasticity), and surface viscosity. Visualization of the surface of water is performed to compare with the numerical results obtained with the developed in-house code. We have found that the surface flow is very sensitive to the surface tension and other configurations. The surface flow velocity obtained from the numerical solution is lower than the experimental result.

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3차원 캐버티 표면의 스톡스 유동 가시화 및 수치해석을 통한 표면 특성 연구 (Study on the Fluid-Surface Characteristics by Using Flow Visualization and Numerical Simulation of Stokes Flow in a Cavity)

  • 허효원;이헌덕;정원혁;조동식;서용권
    • 한국가시화정보학회지
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    • 제9권3호
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    • pp.44-50
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    • 2011
  • In this study, we propose a method for characterizing fluid-mechanical properties of a fluid surface, such as surface dilatational and shear viscosity, by matching the flow visualization and the numerical simulation for a Stokes flow in a three-dimensional cavity. The surface flow is driven by shear stress exerted on the free surface by an external gas flow. The external gas flow is simulated by using a commercial code, while the Stokes flow is calculated by an in-house code. We have found that the surface flow is very sensitive to the surface tension and other properties. The qualitative feature of the surface flow can be reproduced by the parameter tuning.

외부유동에 의한 캐버티 내의 비정상 유동에 대한 수치계산 (Numerical Computation of Unsteady Flow in a Cavity Induced by an Oscillatory External Flow)

  • Yong kweon Suh;Park, Yoon-Hwan;Park, Jun-Gwan;Moon, Jong-Ghoon
    • 한국해안해양공학회지
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    • 제9권4호
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    • pp.194-200
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    • 1997
  • 주기적으로 요동하는 외부유동에 의해 생성되는 캐버티 주위의 2차원 천수유동은 수치적으로 연구하였다. 실험결과와 비교하기 위해 T형의 용기모델을 수치적으로 계산하여 만들었다. 수치계산에서는 캐버티의 종횡비가 전체적인 유동패턴에 크게 영향을 끼치지 않고 종횡비 2에서는 캐버티의 깊은 부분에 정체된 유동형태가 생성되는 것을 제시한다. 높은 레이놀즈 수에서 유동을 가시화 시켰을 때 나다나지 않았던 많은 와류들이 유동장을 특성화 시키고 있다. 외부지역에서의 물질전달은 실험에서 나타난 입자궤적과 잘 일치한다. 캐버티의 외부지역에 위치한 두쌍의 와류가 규모가 큰 시계방향과 반시계방향의 순환유동을 발생시키는 원인이 되는 것이 증명된 셈이다.

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포트란-CFX 연동해석 기법을 이용한 비정상 DC 전기삼투 유동 가시화 (Visualization of Unsteady DC Electro-osmotic flow by using Methods of Coupling Fortran and CFX Codes)

  • 허영근;정종현;서용권
    • 한국가시화정보학회지
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    • 제9권4호
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    • pp.22-27
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    • 2011
  • In this study, we present methods of coupling a commercial code, ANSYS CFX, and the user Fortran codes for solving an unsteady electro-osmotic flow around a pair of electrodes, receiving DC, attached to the top and the bottom walls of a two-dimensional cavity. We developed a module of Fortran programs for solving the ion-transport equations as well as the Poisson equations for the potential to be used in coupling with the CFX. We present how the developed codes are applied to solving the transient DC electro-osmotic flow problem within a simple cavity. We also address various problems encountered during the development process and explain why such problems are raised.

버스 엔진 룸 내 캐버터에서의 3차원 유동해석 (Numerical Analysis of the Three Dimensional Flow in a Cavity of the Bus Engine Room)

  • 윤준용;맹주성;강승규;황용서
    • 한국자동차공학회논문집
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    • 제7권6호
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    • pp.82-90
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    • 1999
  • Numerical analysis of the three dimensional flow in a bus engine room is carried out through this study. The radiator and the fan modeling rare carried out to simulate the flow in an engine room, and the results are focused on the flow in the cavity located in front of the radiator. The numerical simulation results are compared with the experiment . To improve the cooling performance in the bus engine room, the flow inside the cavity is inspected in detail. The complex flow features are found in this region , and the suggestion are made to improve the radiators cooling performance.

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Fractional-Step법을 이용한 비압축성 비정상 Navier-Stokes 방정식의 유한 요소해석 (Finite Element Analysis of Incompressible Transient Navier-Stokes Equation using Fractional-Step Methods)

  • 김형민;이신표
    • 대한기계학회논문집B
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    • 제27권4호
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    • pp.458-465
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    • 2003
  • The main objective of the research is to develop a research code solving transient incompressible Navier-Stokes equation. In this research code, Adams-Bashforth method was applied to the convective terms of the navier stokes equation and the splitted equations were discretized spatially by finite element methods to solve the complex geometry problems easily. To reduce the divergence on the boundaries of pressure poisson equation due to the unsuitable pressure boundary conditions, multi step approximation pressure boundary conditions derived from the boundary linear momentum equations were used. Simulations of Lid Driven Flow and Flow over Cylinder were conducted to prove the accuracy by means of the comparison with results of the previous workers.

에크만 분출 모델을 이용한 캐버티 내의 비정상 유동특성에 관한 수치해석 (A Numerical Analysis of an Unsteady Flow in a Cavity Using an Ekman Pumping Model)

  • 서용권;박춘근;최윤환;문종춘
    • 한국해양공학회지
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    • 제11권4호
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    • pp.102-110
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    • 1997
  • A two dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically with an Ekman pumping model. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The material transport in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles. The Ekman pumping model suggested in this study was found to be satisfactory.isfactory.

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비정상 Navier-Stokes 방정식의 수치해석을 위한 다단계 외재법의 성능 비교 (Comparison of multi-stage explicit methods for numerical computation of the unsteady Navier-Stokes equations)

  • 서용권
    • 대한기계학회논문집B
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    • 제21권2호
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    • pp.202-212
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    • 1997
  • In this study, performance of the multi-stage explicit methods for numerical computation of the unsteady Navier-Stokes equations is investigated. Three methods under consideration are 1 st-, 2 nd-, and 4 th-order Runge-Kutta (R-K) methods. Compared in this estimation is stability, accuracy, and CPU time of each method. The computational codes developed are applied to the two-dimensional flow in a square cavity driven by an oscillating lid. It turned out that at Reynolds number 400, the 1 st-order R-K method is the best, while at 3200 the 2 nd-order R-K is recommended. At higher Reynolds numbers, it is conjectured that the 4 th-order R-K method will be the best algorithm among three due to its highest stability.

터빈 블레이드 캐버티 내 막냉각 특성에 관한 수치해석적 연구 (Numerical Study of Film Cooling Characteristics in Turbine Blade Cavity)

  • 김경석;조형희;강신형
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2008년도 춘계학술대회논문집
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    • pp.648-651
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    • 2008
  • Numerical calculations are performed to simulate the film cooling effect of turbine blade tip with squealer rim. Because of high temperature of inside rim, squealer rim is damaged easily. Therefore many various cooling systems were used. The calculations are based on 100,000 Reynolds number in linear cascade model. A blade has 2% tip clearance and 8.4% rim height. The axial chord length and turning angle is 237mm, 126$^{\circ}$. Numerical calculations are performed without and with film cooling. In a film cooling in the cavity, hot spots of cavity were cooled effectively. However hot spots of suction side rim still remains. The CFD results show that the circulation flow in cavity of squealer tip affects the temperature rise of squealer rim. To maintain the blade integrity and avoid the excessive hot spot of blade, rearrangement of cooling hole is needed.

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