Finite Element Analysis of Natural Convection of Fluids with Low Prandtl Number in a Square Enclosure

유한요소법을 이용한 정방형 밀폐용기내의 플란틀수가 낮은 유체의 자연대류에 관한 연구

Natural convection in a square enclosure was investigated numerically for low prandtl number fluids using Finite Element Method. In case of Ra=10$^{4}$, 10$^{5}$ and 10$^{6}$ the temperature gradient decreases gradually at the lower end of the hot wall(or at the upper end of the cold wall) as prandtl number decreases in the range of 0.01 .leq. Pr .leq. 10. Maximum heat transfer occurs at a somewhat higher point from the lower end of hot wall(or at somewhat lower point from the upper end of the cold wall) and it draws near to the lower end of the hot wall(or draws near to the upper end of the cold wall) with increasing prandtl number. The flow in the enclosure appears as an Unicell Pattern for Ra .leq. 10$^{4}$ and secondarily flows(or tertiary flows) appears in the core region for Ra .geq. 10$^{5}$ . The line joining the center of secondary cells skewes in a clockwise direction as the Prandtl number decreases.

본 연구에서는 수평경계면이 단열이고 수직경계면이 서로 다른 온도로 유지되 고 있는 정방형밀폐용기내의 자연대류에 관해 유동함수-와도모델을 이용한 유한요소법 을 통해 특히 낮은 Prandtl수의 영향에 중점을 두어 경계층흐름이 존재할 때의 유동 및 열전달특성을 조사하였다.