Thermocapillary Bubble Migration at High Reynolds and Marangoni Numbers: 3D Numerical Study

Abstract

Thermocapillary motion of initially spherical bubbles due to the constant temperature gradient in a liquid bounded medium is simulated numerically for low, intermediate, high Reynolds and Marangoni numbers using a three dimensional model. The volume of fluid (VOF) method was used to track the liquid/gas interface utilizing a geometric reconstruction scheme based on the piece-wise linear interface calculation (PLIC) method of Ansys-Fluent (2011) to capture the bubble interface. The simulation results are in good agreement with the earlier experimental observations, and the migration velocity of the bubble is greatly influenced by the temperature gradient which thrusts the bubble from cold to hot regime. The results indicate that the scaled velocity of bubbles decreases with an increase of the Marangoni number, which agrees with the results of previous space experiments. Thermal Marangoni number (MaT) of single bubble migrating in the zero gravity condition ranged from 106 to 904620, exceeding that in the previous reported experiments and numerical data that was limited to 10,000. In addition, an expression for predicting the scaled velocity of the bubble has been developed based on the obtained data in the present numerical study.