Trailing vortex free-surface interaction

Abstract

An investigation of the interaction of a trailing vortex with a free surface has been undertaken for the purpose of understanding the origin and scars and striations. Velocity and turbulence measurements have been carried out through the use of a Laser-Doppler-Velocimeter (LDV) for various positions of the vortex relative to the free surface. The results have shown that the vortex motion affects the free surface and is affected by it. This mutual interaction leads to the development of surface scars composed primarily of heterostrophic vortices normal to the free surface. Furthermore, the velocity and turbulence characteristics are affected such that the vertical components of turbulence decay rapidly and the horizontal components stretch in the horizontal plane. The experiments have provided sufficient understanding of the physics of the phenomenon for the subsequent undertaking of a predictive numerical model.