Bed Friction in Combined Wave-Current Flows

The accurate prediction of shear stresses at the seabed forms an essential element in modelling of the coastal environment. Flows which induce bed friction generally include a mean component (from wind-induced currents or tides) and an oscillatory component (from waves), and this paper describes an investigation into seabed friction under such combined wave-current flow. In particular, it presents new laboratory measurements of the shear stress exerted by waves or wave-like flows on a rough boundary and how that oscillatory component is modified by the addition of a current. The effect of the waves on the current is reported, and the results compared with predictions from wave-current models, including some being developed as part of the present project.