Including tidal currents in a wave-resolving model

Coastal systems are influenced by a combination of waves and tides. In certain cases, tide-induced alongshore currents can be of similar order or even larger than wave-induced currents. Until now, however, no detailed wave-resolving modelling studies included tidal currents. This paper presents a method to implement alongshore tidal currents by adding a pressure term to the alongshore momentum balance and includes modifications to the numerical wave maker to allow for both waves and currents to be generated. The method is successfully validated by comparing simulations with and without inclusion of the tidal current to measurements obtained from the COAST3D data set. Wave prediction is equally good with and without the tidal implementation, but the alongshore current and its distribution over the cross-shore are much better predicted by the model with the new method.