3D numerical modeling of nearshore wave-induced currents

A threedimensional (3D) numerical model for nearshore waveinduced currents is established,in which the phaseaveraged 3D residual momentum flux,surface roller and wave turbulence are introduced as driving forces,and the wavecurrent combined bottom shear stress is taken into account.An energy balance equation of the surface roller is derived,considering the bottom slope,energy transmission rate and roller density.The LarsonKraus formula for the 2D wave turbulent mixing coefficient is extended to its 3D form.A number of experimental cases are used to validate the model,including the wave setup/setdown (1D),undertow (2-DV),longshore current (Q3-D),rip current (2-DH) and the circulation behind a detached breakwater (2-DH).The validation results show that the model is able to effectively describe the waveinduced current phenomena of various dimensions,and the incorporation of the surface roller is mandatory.The uniformity of the longshore current speed profile in the surfzone is related to the vertical turbulent mixing in the effect of waves.