Vertical Structure of Rip-currents in the Nearshore Circulation

Abstract

A number of numerical models have been proposed over the past few decades to investigate rip currents in nearshore circulation zones. Rip currents are the offshore-directed flow generated mainly by wave breaking and momentum transfer over varying topography and they are important in relation to the management of coastal preservation, maintenance, and development. To date, a number of rip current studies have been conducted using depth-integrated two-dimensional (2D) or quasi-three-dimensional (3D) models based on wave-averaged formulations. However, compared with 3D hydrodynamic numerical models, these models are not capable of providing the accurate vertical profiles of current velocity. In this study, we examine the vertical variation of velocities induced by rip-currents using a phase-resolving, 3D Non-Hydrostatic WAVE model (NHWAVE) where an idealized rip channel is used to generate nearshore circulation. The vertical variation of velocities for several locations is investigated and compared with a depth-integrated numerical model for better understanding of depth-dependent hydrodynamics.