PATTERN FORMATION IN NATURAL CONVECTION IN A ROTATING CONTAINER

摘要

We present an experimental and numerical study of the flow patterns that occur in natural convection inside a cylindrical cavity of aspect ratio (radius to height) of 0.25. The working fluid was water with a Prandtl number of 6.0. Observations made for a cavity fixed in the laboratory frame of reference at a Rayleigh number of 2.3 x 10~6 indicate that the convective pattern was steady and organized in a single asymmetric cell. Observations were also made with the cavity placed in a centrifuge. Experimental visualization with a rotating cavity was made with a Rayleigh number of 2.5x10~6 and a Taylor number of 1.7x10~7. With rotation, the flow became time-dependent with two differentiated modes. In the first mode, the flow was composed of regions that seemed to move in an almost independent way during tens of seconds. Then a general motion that lasted a few seconds set in. This sequence of events repeated with varying periods.