Recent Developments in Oscillatory Marangoni Convection

Abstract

A Marangoni Convection Modeling Research group was formed in Japan in order to investigate oscillatory thermocapillary flow sys- tematically over a wide range of Prandtl number (Pr). The research by the group represents the current status of the subject. The present arti- cle reports the work done by the group members. The work is divided into three Pr ranges (low, medium and high) because the cause of oscilla- tions is different in each range. For the low-Pr case, the transition to oscillatory flow is preceded by a steady bifurcation to three-dimensional con- vection. For the first time an experimental proof of this first transition is provided by means of very precise measurements of temperature at dif- ferent azimuthal positions. Then it is discussed that the causes of oscillations in low and medium Pr ranges are well understood. However, the os- cillatory flow of high Pr fluid is not yet fully un- derstood. The critical conditions for high Pr fluid are extremely sensitive to the free surface heat transfer in some situations but very insensitive in other situations. Keyword: Marangoni convection, liquid bridge, oscillations