Deceleration of noncoalescing droplets

Free liquid droplets are observed to glide, or skirt along the surface of a bath of the same fluid, slowing at an exponential rate. The droplet deforms the bath surface creating a dimple which travels along the surface as a wave pulse. Viscous coupling of the droplet and bath surfaces through a thin air film causes a no-slip condition that leads to viscous drag on the bath and perturbs the wave motion of the otherwise free surface. Assuming a linear velocity profile in the bath near the no-slip zone, we show that viscous dissipation in the bath alone accounts for the loss in kinetic energy of the droplet.