Modulation of Marangoni convection in liquid films

Abstract

Non-isothermal liquid films are subject to short- and long-wave modes of Marangoni instability. The short-wave instability leads to the development of convection cells, whereas long-wave instability is one of the primary causes of the film rupture. In this paper different methods for modulation of Marangoni convection and Marangoni-induced interface deformation in non-isotherm liquid films are reviewed. These methods include modification of substrates through topographical features, using substrates with non-uniform thermal properties, non-uniform radiative heating of the liquid-gas interface and non-uniform heating of substrates. All these approaches aim at promotion of temperature gradients along the liquid-gas interface, which leads to emergence of thermocapillary stresses, to the development of vortices and to the interface deformation. Finally, Marangoni convection in a liquid film supported by a substrate with periodic temperature distribution is modeled by solution of steady state creeping flow equations. This approach is justified for low Reynolds numbers and for Marangoni convection in liquids with high Prandtl numbers. The model predicts interaction between Marangoni convection induced by non-uniform wall heating and the Marangoni short-wave instability.

Keywords: Liquid film; Marangoni convection; Marangoni instability; Non-uniform heating; Non-uniform thermal properties; Wall topography.