Contact line stability and "undercompressive shocks" in driven thin film flow

We present new experimental results for films driven by a thermal gradient with an opposing gravitational force. When the gravitational effect becomes non-negligible, the advancing front produces a very large capillary ridge which shows a remarkable tendency to remain stable. This phenomenon can be explained by new mathematical results for a lubrication model of the experi ment. The advancing front evolves into an "undercompressive" capillary shoc k structure which is stable to contact line perturbations, unlike typical c apillary ridges in driven film flows. [S0031-9007(98)07868-5].