AN EVALUATION OF EXPRESSIONS FOR WAVE ENERGY-DISSIPATION DUE TO BOTTOM FRICTION IN THE PRESENCE OF CURRENTS

The effects of a mean current on wave energy dissipation due to bottom friction is investigated. A re-analysis of published measurements shows that current influences on wave energy dissipation are much smaller than suggested by the current-induced variations of the friction factor for the combined wave-current motion. Available models for the combined wave-current boundary layer predict effects of currents on wave energy dissipation with the wrong trend (in contrast with previous conclusions, based on the behaviour of the above friction factor). It follows that, surprisingly, the (presently) most suitable way to describe the effects of currents appears to be to neglect the explicit effects of them on wave energy dissipation.