Dispersion of fine particles by wave-induced mass transport near a circular island

Abstract

We begin with the linearized irrotational theory describing the diffraction of an incoming plane wave by a vertical cylinder. From the free-surface motion, we describe the boundary-layer flow field U0i near that cylinder. The flow field is then used to calculate the modified convective velocities Ui and symmetric dispersivities Dij. Through our calculations we have demonstrated convective flow reversal for both large and very small cylinders. In addition we have characterized four regions of waves and transport about the large cylinder relating to the different characteristics of each region: reflected region, scattered region, plane wave region, and sharp-edged shadow region. Our understanding of the transport velocities and dispersivities allows us to speculate qualitatively on the transport of fine particles near a round island in a diffracted wave field.