Dynamics of ripple bed vortices

 This paper presents the results of an experimental investigation into the dynamics of vortices formed by and shed from ripples under oscillatory motion. Particle Image Velocimetry (PIV) was used to acquire detailed velocity measurements at several phases of oscillation for each of four flow conditions: three purely horizontal oscillations and a ‘real’ wave with a vertical velocity component. For each of the flows, the vortices were located in the flow maps and defined at each time-step by their circulations and sizes. These calculated characteristics were compared with the predictions from a discrete-vortex model (DVM) developed at the University of Wales, Bangor. Received: 22 May 1997/Accepted: 29 January 1998