Effect of free surface heat loss and rotation on transition to oscillatory thermocapillary convection

• Published in: Physics of fluids (1994) 2002-01, Vol.14 (1), p.225-231
• Main Authors: Sim, Bok-Cheol, Zebib, Abdelfattah
• Format: Article
• Language: English
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/1.1428323

Oscillatory thermocapillary convection in an open cylindrical annulus heated from the inside wall is investigated numerically. Results for aspect ratio of 1 and Prandtl number of 30 are obtained to compare the simulations with available space experiments. The influence of surface heat loss as quantified by a Biot number (Bi) or spacecraft or orbital rotation through the Coriolis force, as quantified by a vector Taylor number of magnitude Ta, on the critical Reynolds number ( Re c ) and pattern of convection is investigated. The flow is steady and axisymmetric at sufficiently low values of Re. In the absence of rotation, we observe a two-lobed, isotherm pattern travelling clockwise at the free surface near Re c . A two- or three-lobed pulsating or a three-lobed rotating pattern is observed with increasing Re beyond Re c . Isotherm patterns on the free surface are in good agreement with experimental results. With Ta less than 1, which is relevant to the experiments, the effect of rotation on Re c and flow field is small. Here Re c is found to decrease with increasing Ta. Heat loss from the free surface stabilizes the flow. Increasing Bi leads to an increase in Re c and a small decrease in the critical frequency. The critical parameters and their dependence on the container size are in good agreement with the experiments, assuming Bi ⩽20.