Surface wave effects on energy transfer process in an open-channel turbulent flow*

  The coupled direct numerical simulation and high-order spectral method are performed to study the influence of surface waves on the overlying turbulent flow. The initial wave field is prescribed by the JONSWAP spectrum. The effects of wave age and wave amplitude on the turbulent instantaneous field and statistics are examined. For a slow wave, the near-wall streaky structure is disrupted by surface waves, and the flow is modulated by harmonics as the wave amplitude increases. For a fast wave, the flow pattern in the buffer region is recovered to that of the plate turbulence. Through the spectral analysis on the budget terms of the transport equation of the two-point velocity correlation, the turbulent energy transfer process among different positions and different scales in the presence of surface waves is disclosed.