NUMERICAL-SIMULATION OF BUOYANCY MARANGONI CONVECTION IN 2 SUPERPOSEDIMMISCIBLE LIQUID LAYERS WITH A FREE-SURFACE

Buoyancy-Marangoni convection in a cavity with side heating has been s tudied analytically and numerically in superposed immiscible liquid la yers with a free surface. The analytical results (based on an assumpti on of infinite aspect ratio) indicate that four different flow pattern s are possible and that these results may be anticipated on the basis of the introduction of a new parameter which represents the combined e ffects of Marangoni forces acting at the interface between the two liq uids and at the free surface. It is shown further that the new paramet er is a unique thermocapillary quantity which influences the convectio n in the lower layer. For finite cavities, some numerical results on t he mutual influence of the two layers have been presented. The numeric al results obtained near the centre of the cavity are in good agreemen t with the results from the analytical model for sufficiently large as pect ratios.