A numerical investigation into the interaction between rain and water waves

Rainfall has been observed to damp water waves. However, the long observed effects of rainfall on water waves have not been much investigated numerically. In this paper, numerical simulations are conducted to explore the effect of rainfall on two-dimensional water waves. The Basilisk software, used herein, solves the two-phase, incompressible, Navier–Stokes equations on adaptive Cartesian meshes. In the present simulations, a monochromatic wave is generated within the domain boundary and periodically moves from left to right through the domain. Rainfall with representative drop diameter distributions, as well as accurate terminal velocities, is generated to fall on the monochromatic wave. The energy of the receiving body of water is tracked for evidence of dissipation of the wave induced by the rainfall. The simulation is run for different values of the wave steepness, ranging from non-breaking waves to plunging breakers. It is found that, in no wind conditions, the presence of rainfall can reduce wave energy, particularly in the non-breaking case. In the future, a more realistic configuration with three-dimensional waves and wind will be considered.