Abstract: | The dynamic response of a small, very viscous, coated droplet is examined as additional fluid is deposited into a compressible surface layer. At early times, the surface material behaves like an incompressible fluid and a number of crenations form. These protuberances decrease in size and in number as the compressibility of the coating takes effect, until finally, the droplet again becomes spherical. This sequence of events and its dependence on the compressibility and rheological properties of the fluids are studied. Similar ruffling effects are observed in cell biology, and some of the possible implications of the fluid dynamical model are discussed. |