Fingering instability of thin spreading films driven by temperature gradients

Abstract

THE dynamics of spreading of thin liquid films are important to many technological and biological processes, including tertiary oil recovery, coating processes, the formation and protection of microchips and biological cell interactions. The spontaneous spreading of thin liquid films under capillary forces alone is typically a slow process. An applied force—gravitational or centrifugal, or a surface shear stress—can be used to drive the spreading more quickly1,2. Recent experimental3,4 and theoretical5 studies have revealed that in all of these cases of forced spreading, the liquid front undergoes a fingering instability. Here we report another example of such unstable driven flow, this time caused by the Marangoni effect6, in which a temperature gradient induces a gradient of surface tension which drives the spreading process.