Development of a three-dimensional coupled wave-current model for coastal environments

Abstract

In the past decade, two-dimensional (2DH) morphodynamic modeling systems were developed to simulate the morphological changes due to the combined action of waves, tides and winds. In spite of some significant successes, they are unable to predict complex morphological behaviors, such as inlet infillings in highly dynamic environments during winter energetic wave conditions. For these reasons, the state of the art in morphodynamic modeling tends to evolve towards three-dimensional (3D) modeling systems. In this context, the present study focuses on the development of an unstructured 3D coupled wave-current model taking into account the vertical structure of radiation stresses based on recent theoretical developments. The model is applied to the common breakwater test case and succeeds efficiently to reproduce the wave-driven circulation behind the breakwater. The study investigates also the vertical structure of the flow and the wave-induced setup along a cross-shore profile. The undertow is well-predicted by the model in the surf zone and the wave-induced setups predicted by the 3D model are about 30-40% greater than those simulated by a 2DH approach. This important aspect could be relevant in storm surge and inundation studies for which the quality of the predictions could be strongly improved by using a 3D fully coupled wave-current model.