Clarification of Marangoni Convection under microgravity conditions for high quality crystal growth

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Marangoni convection in the melt is investigated for improvement of the quality of the single crystal grown from a melt. The Marangoni convection in a liquid bridge was investigated the mechanism of the transition process from two-dimensional steady flow to three-dimensional periodic flow through three-dimensional steady flow with increasing of the driving force of the thermally induced surface tension difference. The comparison of the results of the drop shaft experiments and the normal-gravity experiments cleared that the super steady region that is observed under normal-gravity conditions vanished under micro-gravity conditions. The temperature frequency in a liquid bridge induced by Marangoni convection classified into following types : steady, periodically pulsating, periodically rotating, quasi-periodic, and complex. We derived the model equations for the temperature oscillation patterns. The equations agree well with the experimental results. The equation clarified the features … More of each temperature fluctuation types. The transition process of the temperature fluctuation types depends on the shape and volume of the liquid bridge and/or the gravity level.Local heat flux on the solid-liquid interface was investigated numerically through the step change of the gravity level from 1G to micro-G induced by the drop shaft. The numerical results agree well with the experimental ones. This shows the numerical analysis explains well the heat transfer phenomena in liquid bridges. The heat flux distribution on the solid-liquid interface could be explained commonly by the combination of the following non-dimensional values : the position normalized by the liquid bridge length, Marangoni number and Prandtl number. The numerical simulation clarified the effect of remain gravity on gravity convection in the melt under Long Capillary method.These results clarified the mechanisms of the Maranogni convection in the melt. Therefore they are useful for improvement of the quality of the grown crystal from a melt. Less