Bottom friction in random waves plus current flow

Bottom friction in random waves plus current flow is presented. The model is an extension of the Myrhaug [Coastal Eng. 24 (1995) 259] approach for random waves alone. The effect of random waves on the bottom friction is studied by assuming the wave motion to be a stationary Gaussian narrow-band random process, and by using friction coefficient formulas for sinusoidal waves. The data used for comparison are obtained from statistical analysis of direct measurements of bottom shear stresses made in the UK Coastal Research Facility under combined random waves and orthogonal as well as near-orthogonal currents.