Wind generation of waves: Energy and momentum transfer - An overview with physical discussion

The study considers the generation of surface water waves by wind through pressure and shear stress acting on the surface. The situations of temporal growth of an infinitely long uniform wave train and of down-wind growth of a stationary non-uniform wave field are treated. The mechanisms of energy and momentum transfer between the wind and the waves are considered and it is explained how the ‘wave Reynolds stress’ and the wave set-down are contributing to a force balance over the water column. The role of the wind forcing for the wave drift and a mean current is shown. The analogy between energy dissipation by wave breaking and wave generation by a harmonic surface shear stress is discussed together with the transfer of momentum to the ocean currents by breaking waves.