Abstract
Oscillatory thermocapillary flow is investigated experimentally in liquid bridges of high Prandtl number fluids. The
effect of heat transfer from the liquid free surface on the onset of oscillations is investigated. The heat transfer is mainly due to conduction as well as the natural convection of air around the liquid bridge. The airflow in the present work is varied by varying the temperatures of the cold wall and the ambient air. It is found that when the free surface is nearly flat, the critical Marangoni number (Macr) varies substantially when the temperature of the cold wall or the ambient air is varied, but when the surface is highly concave, Macr is not affected appreciably. The present work shows that it is important to know the surrounding air condition when one compares various data for the onset of oscillations for liquid bridges with nearly flat free surfaces.
