Influence of Aspect Ratio on the Onset of Thermocapillary Oscillatory Convection in a Floating Half Zone of Large Prandtl Number Fluid

The onset of oscillatory thermocapillary convection in a floating half zone of 10 cst silicon oil (Prandtl number 105.6) is studied by the three-dimensional and unsteady numerical simulation in microgravity environment (g = 10^-4 g_earth). The results show that the steady and axi symmetric convection, for a fixed liquid bridge volume ratio V_l/V₀ = 1, transits directly to the oscillatory convection if geometrical aspect ratio A is larger than the critical value A_c = 1.25, but transits to the oscillatory convection via the steady and non-axisymmetric flow if A is smaller than the critical value A_c. The result means that there are two bifurcation transitions in a liquid bridge of the large Prandtl number fluid with a smaller aspect ratio A.