The dynamics and stability of thin layers, membranes, films, interfaces and surfaces of complex fluids is investigated. Of special interest is the relation between dynamical processes within a surface layer and the macroscopic motion of the layer itself.
Examples are surface waves in polymers and amphiphilic sol-gel systems.
Surface waves are exponentially damped going into the bulk and therefore these excitations probe surface material parameters. Surface waves of visco-elastic films or interfaces constitute transverse undulations of the film or interface. The dispersion relation is a very complicated function involving a host of visco-elastic parameters of the film or interface, e.g. the dilational and transverse viscosities, transient elastic moduli, and relaxation times, as well as bending rigidity, static compressional modulus and surface tension.