Rapidly moving dynamical contact lines: an inertial-capillary perspective

Tuesday, March 27, 2018 - 10:50am - 11:20am
Lind 305
Paul Steen (Cornell University)
How fast can a liquid wet (or unwet) a solid support? This is important to a range of industrial applications from semiconductor fabrication by immersion lithography to the management of liquid propellants in spacecraft. 'Dynamical contact line' studies have historically taken a visco-capillary or low Reynolds number perspective. This perspective brings to mind stress singularity, slip lengths, microscopic and macroscopic contact angles, etc. – all fundamental issues raised in the ground-breaking studies of Scriven, Dussan V., Hocking, Cox, de Gennes and others. There is another perspective, however. For speeds beyond the region of stick-slip, for example, liquid inertia and surface tension compete while damping is weak. To first order, these are perfect fluid reconfigurations of capillary surfaces with moving contact lines. We demonstrate how to characterize the mobility of a rapidly moving contact line by measuring contact angles, displacements and speeds of the contact line. More generally, we highlight results from the inertial-capillary regime, arguing for the utility of the inertial-capillary perspective.