Space-time characteristics of wind turbulent pressure field at wave surface

The wind pressure field at the wave surface, with fluctuations several orders of magnitude smaller than the mean atmospheric pressure, has a notable impact on the wave energy growth. The time-variant and irregular wave field poses great challenge to the full space-time measurement of the surface pressure. We present a simulation-based study of the space-time characteristics of the surface pressure field. The numerical tool is a combined turbulence solver and wave-phase-resolved model, where the wind turbulence is simulated with large-eddy simulation and the nonlinear wave field simulated using a high-order spectral method. The joint probability distribution of the surface pressure and the vertical surface velocity is found to resemble that of turbulent flows over a compliant wall. We also conduct spectral analysis on the surface pressure field to obtain the wavenumber-frequency spectrum. While the turbulent pressure fluctuations have a convection velocity comparable to turbulent flows over a fixed flat wall, a distinct wave effect is identified. The wavenumber/frequency peak of the wave-coherent pressure field is found to deviate from that of the wave field, suggesting nonlinearity in the turbulence-wave interactions.