Surface disturbances due to trailing vortices

The characteristics of the surface signatures resulting from the interaction of the trailing vortices with the free surface have been investigated both theoretically and experimentally. The vortices were created through the use of three lifting surfaces of different shape and aspect ratio (two Delta wings and a rectangular foil). The surface disturbances have been classified into two groups (striations and scars) and the evolution of each type has been expressed in terms of the governing parameters such as the depth of generation of vortices, mutual induction velocity, and the initial vortex spacing. It has been shown that the surface signatures are a consequence of the strain field resulting from the nonuniform surface-velocity distribution and that they are not simple capillary-gravity waves. A turbulence model has been used to establish reasonable correlation between the theoretical and experimental results.