• 제목/요약/키워드: Bicellular flow

검색결과 3건 처리시간 0.018초

넓은 수평 환형 공간에서의 중간 Prandtl수 유체의 자연 대류의 천이 (Free Convective Transition of Intermediate Prandtl-Number Fluids in a Wide-Gap Horizontal Annulus)

  • 유주식
    • 대한기계학회논문집B
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    • 제24권2호
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    • pp.169-176
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    • 2000
  • Natural convection in a wide-gap horizontal annulus is considered, and the transition of flows and the bifurcation phenomenon are investigated for the fluids with Pr=0.2 and 0.3. At Pr=0.2, a bicellular flow pattern is observed at high Rayleigh number, and the solution is unique. At Pr=0.3, both the steady unicellular and bicellular flows exist above a certain critical Rayleigh number. For the fluids of Pr=0.2, the bicellular flow can be obtained by the impulsive heating of the inner cylinder, but it is not obtained from the zero initial condition for Pr=0.3. Hysteresis phenomena have not been observed. A transition from a bicellular flow to a unicellular flow occurs for Pr=0.3.

일정 열 유속으로 냉각되는 안쪽 실린더를 갖는 수평 환형 공간에서의 공기의 자연 대류 (Natural Convection of Air in a Horizontal Annulus with the Inner Cylinder Cooled by Constant Heat Flux)

  • 유주식;엄용균;김용진
    • 설비공학논문집
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    • 제12권8호
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    • pp.755-762
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    • 2000
  • Natural convection of air in a horizontal annulus with the inner cylinder cooled by the application of a constant heat flux and the isothermally heated outer cylinder is considered. The bifurcation phenomenon of flow patterns and the heat transfer characteristics are numerically investigated. The zero initial condition induces a unicellular flow in a half annulus. A bicellular flow consisting of two counter-rotating eddies in a half annulus can be obtained above a certain critical Rayleigh number. A transition from the bicellular to the unicellular flow occurs with a decrease in Rayleigh number. Hysteresis phenomena have not been observed. In the regime of dual flows, the overall Nusselt number of the bicellular flow is greater than that of the unicellular flow.

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일정 열유속 실린더를 갖는 수평 환형 공간에서의 공기의 이중 자연대류 유동 (Dual Natural-Convective Flows of Air in a Horizontal Annulus with a Constant Heat Flux Cylinder)

  • 유주식
    • 한국전산유체공학회지
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    • 제4권2호
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    • pp.1-8
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    • 1999
  • Natural convection in a horizontal annulus with the inner cylinder heated by the application of a constant heat flux and the isothermally cooled outer cylinder is considered, and the transition of flows and the bifurcation phenomenon are numerically investigated for air with Pr=0.7. The zero initial condition always induces a crescent-sheped eddy flow. A bicellular flow in which the fluid descends along the vertical central plane of the annulus can be obtained at high Rayleigh number by introducing artificial numerical disturbances. Dual solutions are found above a certain critical Rayleigh number. Hysteresis phenomena have not been observed.

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