Stokes drift for inertial particles transported by water waves

The authors study the effect of surface gravity waves on the motion of inertial particles in an incompressible fluid. They perform an analytical calculations based on perturbation expansions which allow them to predict the dynamics of inertial particles in the deep-water regime. The authors find that the presence of inertia leads to a non-negligible correction to the well-known horizontal Stokes drift velocity. Moreover, they find that the vertical sedimentation velocity is also affected by a drift induced by waves. The latter result may have some relevant consequences on the rate of sedimentation of particles of finite size. They underline that the vertical drift would also be observed in the (hypothetical) absence of the gravitational force. Kinematic numerical simulations are performed and the results are found to be in excellent agreement with the analytical predictions, even for values of the parameters beyond the perturbative limit.