抄録
The critical Rayleigh number for the onset of thermal convection in a horizontal rectangular parallelepiped cavity heated from below is evaluated numerically, and the three-dimensional flow pattern of the convection and the temperature distribution at the critical state are investigated. The top and bottom boundaries of the cavity are assumed to be perfectly heat-conductive, while the four sidewalls are assumed to be thermally insulating. The critical Rayleigh number is obtained to be 3389 for the case of cubic cavity and the velocity field at the critical state is revealed to have one global circulation. The critical condition and the flow field are obtained also for the cases other than the cubic cavity. It is found that the preferred mode is not always two-dimensional finite rolls with axes parallel to the shorter side, which differs from the conclusion derived for the case of perfectly conducting sidewalls by Davis.
