Dimple dynamics beneath lubricated droplets

Liquid droplets on solid surfaces with a thin oily lubricant coating have recently emerged as a route for enhanced droplet mobility. Previous experiments have hinted that a dimple of lubricant may be trapped beneath such droplets. However, the details of the evolution of this dimple, including its lifetime and effect on the equilibrium and dynamics of the droplet, remain mysterious. Using a combination of experimental measurements and a simplified mathematical model, we will show that such dimples can be surprisingly long-lived and discuss their effect on the behaviour of droplets on lubricated surfaces.