Experiments on the Steady Streaming Generated by a Monochromatic Surface Wave over Smooth and Rough Bottoms

The oscillating motion generated by a propagating surface wave over the bottom surface develops a bottom boundary layer whose dynamics is also of oscillating nature. The evaluation of the velocity field occurring close to the bottom is of particular importance, since it allows for a more accurate evaluation of the bottom shear stresses developing between the fluid and the bottom. Such stresses are relevant for, e.g., sediment mobilization and subsequent seabed modifications, as well as wave attenuation/dissipation over smooth and rough beds. The present contribution focuses on a suite of experimental tests performed at the Hydraulics and Maritime Engineering laboratory of Università Politecnica delle Marche (Ancona, Italy). In such experiments, Lagrangian and Eulerian velocity flow fields under progressive monochromatic surface waves over smooth and rough bottoms were obtained through particle tracking over the water column.