Oscillatory Marangoni flow in half-zone liquid bridge of molten tin

In order to evaluate the experimental observations at NASDA, a long-run numerical simulation was conducted on a realistic model of a half-zone liquid bridge of molten tin, including the supporting iron rods. The model is identical to the apparatus of NASDA's experiment with a radius of 1.5 mm and length of 3 mm. Using time-dependent imposed temperatures on both ends of the rods, which are calculated based on the experimental temperature recordings measured through two thermocouples, the numerical results reproduce the experimentally observed oscillations of local melt free surface temperature with different frequencies and explain the experimental results. The present study also reveals that the first and second critical Marangoni numbers are similar to those predicted by our previous studies corresponding to the marginal stability limits, and indicates that very sensitive temperature measuring system must be developed to detect experimentally the temperature oscillations right after the incipience of oscillatory Marangoni flow, i.e., to determine the critical conditions of flow transitions experimentally through temperature measurements.