The interaction between capillary waves and a current and wave decay

Abstract

Results of experiments on capillary-wave decay and energy transfer to mean currents are presented. The conditions investigated were those of a progressive wave train propagating on still water, on a constant current and on a spatially varying current. The waves were generated by either a mechanical or a pneumatic wave maker and the wave maker usually excited cross-wave motion. Thus the study also provides data on cross-wave generation and growth under these conditions. In particular these results indicate that the cross-waves obtain energy from a constant current as well as a spatially varying current. The progressive-wave energy was separated from that in the cross-waves by spatial averaging. When this is done the wave-current interaction and wave decay can be described by a first-order theory which includes viscous dissipation.