Interaction of a solitary wave with an array of macro-roughness elements in the presence of steady currents

The present study focuses on the effects of following and opposing steady currents on the interactions of a solitary wave with an array of macro-roughness elements, placed on a berm beach. A series of laboratory experiments and high-fidelity numerical simulations are conducted. The large eddy simulations are carried out using the open source computational fluid dynamics package, OpenFOAM. Wave breaking conditions on the berm are found to be controlled by the intensity of the currents. The opposing currents influence the layer of water rushing up the macro-roughness elements, leading to asymmetric runup patterns. Furthermore, the vortices forming around the elements' sharp edges, resulting from the interactions of the wave with the elements, are modified to a large extent due to the combined wave and current effect. The elliptical vortex tubes become up to ~20% wider under the effect of the following current flow, whereas their size is reduced by up to ~90% when the opposing currents are present. The following currents enhance the bed shear velocity, leading to intensified bed shear stress zones throughout the macro-roughness environment. On the other hand, the intensification of the bed shear velocity and corresponding stress occurs on the seaside in the presence of opposing currents. Overall, the results indicate that the currents entirely change the hydrodynamics of the interactions between the solitary wave and macro-roughness environment.