A Calculation Model of the Equilibrium Scour Depth for Monopile Foundations Under Waves and Currents

Abstract

Scour behavior around a monopile foundation of offshore wind turbines (OWTs) should take into account the effect of combined waves and currents. To obtain an accurate equilibrium scour depth, a calculation model was proposed herein on the basis of the energy balance concept. Under the condition of wave and current coexistence, the composite flow velocity was proposed to express the flow field around the monopile foundation. To consider an arbitrary scour shape, the total volume of the deposit sediments removed from the scour hole was obtained by integrating two nonlinear functions. The equilibrium scour depth predicted by the model shows good agreement with the experimental results available in the literature. The calculation model of the equilibrium scour depth under combined waves and currents may also provide a guide for offshore engineering practice and design.