• Title/Summary/Keyword: 준압축성

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A Numerical Analysis of Streamwise Vortices in Turbulent Boundary Layers (주유동방향 와동과 난류경계층과의 상호작용에 관한 수치적 연구)

  • 김정한;양장식;김봉환;이기백
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.1
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    • pp.31-40
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    • 2000
  • This paper describes the numerical computations of the interaction between the streamwise vortex and a flat plate 3-D turbulent boundary layer. In the present study, the main interest is in the behavior of the streamwise vortices introduced in turbulent boundary layers. The flow behind a vortex generator is modeled by the information that is avilable from studies on the dalta winglet. An algorithm of the solution of the incompressible Navier-Stokes equations for three-dimensional turbulent flows, together with a two layer turbulent model to resolve the near-wall flow, is based on the method of artificial compressibility. The present results show boundary layer distortion due to vortices, such as strong spanwise flow divergence and boundary thinning, and have a good agreement with the experimental data.

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A Numerical Simulation of Longitudinal Vortex in Turbulent Boundary Layers (3차원 난류경계층 내에 존재하는 종방향 와동의 유동특성에 관한 수치적 연구)

  • Yang, Jang-Sik;Lee, Ki-Baik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.6
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    • pp.802-813
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    • 2000
  • This paper represents numerical computations of the interaction between the longitudinal vortex and a flat plate 3-D turbulent boundary layer. In the present study, the main interest is in the behavior of longitudinal vortices introduced in turbulent boundary layers. The flow field behind vortex generator is modeled by the information that is available from studies on the delta winglet. Also, the Reynolds-averaged Navier-Stoke equations for three-dimensional turbulent flows, together with a two-layer turbulence model to resolve the near-wall flow, is solved by the method of pseudo compressibility. The present results show that the boundary layer is thinned in the regions where the secondary flow is directed toward the wall and thickened where it is directed away from the wall, and have a good agreement with the experimental data.

Numerical Analysis on the Flow Field and Heat Transfer Characteristics of Longitudinal Vortices in Turbulent Boundary Layer - On the Common Flow Up - (3차원 난류경계층 내에 존재하는 종방향 와동의 유동장 및 열전달 특성에 관한 수치해석(II) - Common Flow Up에 관하여 -)

  • Yang Jang-Sik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.9
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    • pp.799-807
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    • 2005
  • The flow characteristics and the heat transfer rate on a surface by the interaction of a pair of vortices are studied numerically. To analyze the common flow up produced by vortex generators in a rectangular channel flow, the pseudo-compressibility viscous method is introduced into the Reynolds-averaged Navier-Stokes equation for 3-dimensional unsteady, incompressible viscous flows. To predict turbulence characteristics, a two-layer $k-\varepsilon$ turbulence model is used on the flat plate 3-dimensional turbulence boundary The computational results predict accurately Reynolds stress, turbulent kinetic energy and flow field generated by the vortex generators. The numerical results, such as thermal boundary layers, skin friction characteristics and heat transfers, are also reasonably close to the experimental data.

Numerical Analysis on the Flow Field and Heat Transfer Characteristics of Longitudinal Vortices in Turbulent Boundary Layer - On the Common Flow Down - (3차원 난류경계층 내에 존재하는 종방향 와동의 유동장 및 열전달 특성에 관한 수치해석(I) - Common Flow Down에 관하여 -)

  • Yang Jang-Sik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.9
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    • pp.789-798
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    • 2005
  • This paper is a numerical study concerning how the interactions between a pair of the vortices effect flow field and heat transfer. The flow field (common flow down) behind a vortex generator is modeled by the information that is available from studies on a half-delta winglet. Also, the energy equation and the Reynolds-averaged Wavier-Stokes equation for three-dimensional turbulent flows, together with a two-layer turbulence model to resolve the near-wall flow, are solved by the method of AF-ADI. The present results predict that the boundary layer is thinned in the regions where the secondary flow is directed toward the wall and thickened where it Is directed away from the wall. Although some discrepancies are observed near the center of the vortex core, the overall performance of the computational model is found to be satisfactory.