A numerical model of the air flow above water waves. Part 2

Further results from the nonlinear numerical model of the air flow in a deep turbulent boundary layer above water waves described in Gent & Taylor (1976) are presented. The results are calculated with the surface roughness z 0 both constant and varying with position along the wave. With the form used when z 0 varies, the fractional rate |ζ| of energy transfer per radian advance in phase due to the working of the pressure forces is larger than for z 0 constant both when the transfer is from wind to waves and when it is from waves to wind. The latter case occurs when the waves are travelling faster than, or against, the wind. The energy transfer rates are compared with other theoretical predictions and with recent field observations.