OSCILLATORY PHENOMENA OF LOW-PRANDTL-NUMBER FLUIDS IN A RECTANGULAR CAVITY

Abstract

The oscillatory phenomena in natural confection of low-Prandtl-number fluids were studied numerically in a rectangular cavity with horizontal temperature gradient at Prandtl number Pr = 0.01, aspect ratio A = J, 2, or 4, and Rayleigh number Ra = 10⁴, 10^s, or 10⁶. In the case of A = 1 a main strong round roll cell was formed at Ra = 10⁴. However, at Ra = 10⁵ and 10⁶, two secondary roll cells in the core of a main roll cell were formed and rotated around the center of the system. The flow was oscillating. In the case of A = 2, i.e., a taller regime, the shape of the main roll cell varied with time at and above Ra = 10⁴, and then the secondary complicated weak roll cells were formed above and below the main roll cells. This resulted in oscillatory phenomena even at Ra = 10⁴. In the case of A = 4, three main roll cells were formed. At Ra = 10⁵, secondary roll cells were formed between the main roll cells and then oscillation of flow occurred.

Notes

Address correspondence to Professor Hiroyuki Ozoe, Kyushu University, 6-1 Kasuga-koen, Kasuga 816, Japan.