Physics (Internal)

Droplet impact and the far-from-equilibrium dynamics of wetting

This event is part of the Biophysics/Condensed Matter Seminar Series.

Abstract:
When a liquid drop approaches a flat solid surface, the air beneath it is compressed, flattening the bottom of the drop and forcing initial contact to occur in a ring-shape, trapping a pocket of air in its center as two wetting fronts rapidly expand both outward and inwards to completely wet the surface. These far-from-equilibrium dynamics occur over fleeting time—and diminutive length-scales that are difficult to probe experimentally and have thus far remained elusive. We combine total internal reflection (TIR) microscopy with a novel virtual frame technique (VFT) to directly observe the sub-micron length scales above a solid surface as the drop approaches, impacts and then spreads over it. In this talk I will present a full description of these impact dynamics and try to explain the parts we currently understand.