EFFECT OF THE CORIOLIS-FORCE ON THERMAL-CONVECTION UNDER MICROGRAVITY

In contrast to the generally accepted viewpoint, it is shown that the Coriolis force caused by the rotation of an orbital station about Eart h and the station centroid can strongly affect natural convection duri ng fluid-flow orbital experiments. Various aspects of this influence a re investigated in detail. The focus is on the interaction of the Cori olis force and the harmonically oscillating gravity force on the inten sity of two-dimensional thermal convection in a rectangular enclosure with rigid walls. It is shown that the dependence of the maximum root- mean-square velocity on the Ekman number or microacceleration frequenc y has a distinct resonant character. The height of the resonance peak is significantly influenced by the aspect ratio of the enclosure and b y the orientation of the microacceleration vector and the angular velo city vector relative to the enclosure and each other. Special attentio n is given to nonlinear effects caused by the convective terms of the Navier-Stokes equations.