Numerical Study of Natural Convection in Porous Media Bounded by Short Vertical Annulus

단형 수직환형 다공성 물질에 있어서의 자연 대류에 대한 수치해석

Natural convection heat transfer has been investigated numerically in the vertical annulus filled withsaturated porous material for the aspect ratio less than unity. The inner wall of the annulus is exposed to constant heat flux condition and the outer wall is cooled to keep isothermal condition. The upper and the lower horizontal wall are assumed to be insulated. Under conditions ranging 50 .leq. Ra .leq. 10000, 1 .leq. RD .leq. 12, the characteristics of flow and heat transfer have been investigated. The results show that average Nusselt numbers increase when the radius ratio increases and the multicellular flows are not detected under the present conditions. Isothermal lines are plotted within the porous media. Temperatures of the inner wall with constant heat flux conditions and the local heat flux rate of the cooled outer wall with constant temperature are also obtained.

본 연구에서는 종횡비가 1보다 크고 내부 벽면에 일정한 열유속을 가지고 외부벽은 등온으로 유지되며 나머지 벽은 단열된 수직환형 원통형에 대한 연구를 바탕으로 같은 경계조건으로 종횡비를 1이하로 감소할 때에 Darcy의 법칙을 기초로 유한차분법을 사용, 수치적으로 해석하여 다세포 유동의 존재 여부와 온도 분포 및 열전달율을 계산하였다.