THERMOCAPILLARY BUBBLE MIGRATION IN CONFINED MEDIUM

The aim of this paper is to advance the numerical investigation of uns teady thermocapillary migration of gas bubbles in a fully confined non -isothermal liquid. The relevance of the study is twofold: to support space experiments such as the Italian experiment on board of the Space lab IML-2 Mission and to fill a lack in thermocapillary migration stud ies mainly devoted to slow motion in infinite medium (so that no compa rison is possible with experimental results). The motion due to surfac e tension gradients of one and two spherical bubbles inside a liquid f illing a cylindrical box, with differentially heated ends disks, is he rein analysed, both for linear and quadratic temperature dependence of the surface tension at the bubble-liquid interface. A Galerkin finite elements method is employed to solve the unsteady axisymmetric govern ing equations casted under a velocity, vorticity, temperature formulat ion. The flow field into the liquid medium, the net force exerted on t he bubbles, the bubbles speed and location are determined as a functio n of the time; pressure and temperature fields around the bubble are r eported. Copyright (C) 1996 Elsevier Science Ltd