높은 Rayleigh 수에서 원형 실린더가 존재하는 사각형 실린더 내부의 자연대류에 관한 수치적 연구

A numerical study of natural convection in a square enclosure with a circular cylinder for high Rayleigh number

  • 유동훈 (부산대학교 대학원 기계공학부) ;
  • 윤현식 (부산대학교 첨단조선공학 연구센터) ;
  • 하만영 (부산대학교 기계공학부) ;
  • 김병수 (부산대학교 대학원 기계공학부)
  • 발행 : 2008.11.05

초록

Numerical calculations are carried out for the natural convection induced by temperature difference between a cold outer square cylinder and a hot inner circular cylinder for Rayleigh number of $Ra=10^7$. This study investigates the effect of the inner cylinder location on the heat transfer and fluid flow. The location of inner circular cylinder ($\delta$) is changed vertically along the center-line of square enclosure. The natural convection bifurcates from unsteady to steady state according to $\delta$. Two critical positions of ${\delta}_{C,L}$ and ${\delta}_{C,U}$ as a lower bound and an upper bound are ${\delta}_{C,L}=0.05$ and ${\delta}_{C,U}=0.18$, respectively. Within the defined bounds, the thermal and flow fields are steady state. When the inner cylinder locates at ${\delta}{\geq}{\delta}_{C,U}$, the space between the upper surface of inner cylinder and the top surface of the enclosure forms a relatively shallow layer where the natural convection characterized as the pure Rayleigh-Benard convection forms alternately the upwelling and downwelling plums, as a result that a series of cells known as Benard cells is derived.

키워드