Laboratory experiments on the effects of mechanical waves on the mean and turbulent flow under the wind waves

摘要

The response of the secondary flow circulation existing in a wind-wave tank to two sets of mechanically generated waves (i.e., the waves following and opposing to the wind) are examined using a two-component laser-Doppler anemometer. The primary purpose is to study how the mechanical waves interact with the mean current flow under the wind waves. It is found that the waves following the wind slowed down the primary circulation in the tank and strengthened the secondary circulation, whereas the waves opposing the wind speeded up the former circulation and decayed the latter one. The effects of the mechanical waves on the secondary flow are qualitatively consistent with prediction of the CL2 mechanism of Langmuir circulations, proposed by Craik (1977) and Leibovich (1977).