OBSERVATIONS AND NUMERICAL MODEL RESULTS OF MORPHODYNAMIC FEEDBACK OWING TO WAVE-CURRENT INTERACTION

International audiencePredicting the evolution of mound formations in the nearshore, both natural (e.g. bars) and man-made (e.g. nourishments) requires an understanding of mixed wave-current flow on sediment transport. MODEX (Morphological Diffusivity EXperiment) used a wave-current-sediment flume to observe in detail the evolution of a sand mound in shallow water. Imposed flow included waves-alone, currents-alone, and combined wave-currents. MODEX observations show the impact of currents on waves around the mound and the feedback with morphology. Here, a wave-resolving model SWASH is used to simulate flow patterns around the mound as it diffuses, showing the impact of wave-current interaction on mound evolution. Further, simulations initialized with a diffused mound show the feedback between 3D bed deformation and wave-current flow structures. The results provide a framework for understanding and implementing intra-wave sediment transport in wave-resolving models. Extensions of the results to field conditions with mixed wave-current energy will be explored