FORCES ON A SPHERE UNDER LINEAR PROGRESSIVE WAVES

Abstract

The rms horizontal forces which result from the action of a linear, deep and intermediate water, laboratory scale waves were measured on submerged spheres removed several diameters from the free surface. The study focuses on unseparated flows encountered at small values of (d0/D), where d0 is the orbital diameter and D is the sphere diameter. Under these conditions, a steady streaming around the vertical equator of the sphere was observed, giving rise to a circulation in the sense of rotation of the orbital motion. This phenomena was found to diminish the resultant of the wave pressure on the sphere predicted by potential theory. In approaching the onset of separation, the drag coefficients were found to compare in size with those reported for similar motions in steady unidirectional flow.