Study on the transition mechanism of thermocapillary convection in a liquid bridge

In this paper, the transition mechanism from steady to oscillatory flow of thermocapillary convection (Marangoni convection) is investigated. Two-dimensional simulations with several liquid bridge sizes were conducted in order to clarify the dependency of liquid bridge size on the onset of oscillatory flow. The results show that the formation of velocity distribution on free surface is closely related to temperature dependency of kinematic viscosity and it has influence upon the onset of oscillation. From these results, a basic model for understanding of transition mechanism of Marangoni convection was proposed. In this model, the inertial force generated on free surface and the concept of fluid instability were considered. A novel dimensionless parameter which indicates the onset condition of oscillation, effective Marangoni number, was also proposed and evaluated.