MARANGONI CONVECTION WITH 2 FREE SURFACES

A numerical model is presented for a two-dimensional surface-tension-d riven flow with two free surfaces, as is the case for a stationary ful l-penetration weld. Focus is on the flow patterns with the presence of two free surfaces and how they differ from those with one free surfac e. A standard splining scheme is used to numerically solve the governi ng equations with primitive variables u, v, p, T and the locations of the free surfaces. Results for several combinations of Reynolds number , capillary number, Bond number, and external pressure are presented I f is found that with low Reynolds number, thermocapillary flows with t wo free surfaces have stronger secondary vortex than those with one fr ee surface. For two-free-surface flaws with high Reynolds number, ther mocapillary forces at the bottom free surface are strong enough to gen erate a secondary vortex that is comparable to the primary vortex gene rated by the thermocapillary forces at the top free surface. Furthermo re, two-free-surface flows are more flexible than one-free-surface flo ws; therefore, under the same conditions, the former oscillate with a higher frequency than the later. This is consistent with prior experim ental observation and analytical investigation.