An efficient RANS numerical model for cross-shore beach processes under erosive conditions

Abstract

In this work, a new numerical model for cross-shore beach profile evolution, IH2VOF-SED, is developed. It consists in the bidirectional coupling of a 2D RANS hydrodynamic solver and a sediment transport module. The resulting model is extensively validated against three benchmark cases at different scales, attending to the hydrodynamics, bottom shear stress and bathymetry evolution. Comparisons between experimental and numerical results show a good agreement for both the flow variables and the seabed evolution in all the validation cases without making use of calibration parameters. Additionally, the qualitative analysis of the results is in accordance with previous experimental observations of sediment transport induced by breaking waves. The computational cost is greatly reduced to about 1/10 of other available RANS models. As a novel aspect regarding RANS models, the model is able to simulate the swash zone and changes in the position of the coastline. A good compromise between precision and computational cost is achieved, allowing for an in-depth analysis of the processes leading to the cross-shore profile evolution.