VELOCITIES AND BED FRICTION IN COMBINED FLOWS

Abstract

Velocity measurements have been made with a laser doppler anemometer in a steady flow flume with an oscillating bed. The velocity profiles in these tests, for which the oscillation was at right angles to the steady current, were found to be qualitatively similar to those observed in previous measurements with currents collinear with the direction of oscillation. Measured time-mean velocity profiles show moderate agreement with the predictions of the models of Grant & Madsen (1979) and Christoffersen & Jonsson (1985) in the outer layer (the 'current boundary layer') but poor agreement close to the bed (the 'wave boundary layer').