Analytical Study on Drift of Small Floating Objects under Regular Waves

Abstract

An improved analytical derivation was present on the drift motion of small rigid floating objects of arbitrary shapes under regular surface waves. The approach follows the slope-sliding model but with two new developments: (1) the incorporation of the Lagrangian movement of the small floating object in the wave motion including the heave motion, and (2) more detailed description of the associated hydrodynamic forces that are comprised of the gravitational force, pressure force, and viscous skin friction modeled by a drag coefficient. The analysis first yields the Stokes drift when the object is infinitely small, which is as physically expected. Subsequently, the predicted drift of a small floating circular plate is derived based on the assumption of nonseparated flows around the object. The comparison between the predicted wave-induced drift and previous experimental measurements shows satisfactory agreement with a set of tuned hydrodynamic coefficients that are consistent with previous related studies.