SCALING OF THE TRANSITION TO PARAMETRICALLY DRIVEN SURFACE-WAVES IN HIGHLY DISSIPATIVE SYSTEMS

We present an experimental study of the onset of the Faraday instabili ty in highly dissipative fluids. In this regime of high viscosity and shallow fluid depth, we find that the critical acceleration for the tr ansition to parametrically excited surface waves scales as a function of two dimensionless parameters corresponding to the ratios of the cri tical driving amplitude height and viscous boundary layer depth to the fluid depth. This scaling, which exists over a wide range of fluid pa rameters, identities the proper characteristic scales and indicates th at a Rayleigh-Taylor type mechanism drives the instability in this reg ime.