Non-hydrostatic modelling of infragravity waves under laboratory conditions

The non-hydrostatic wave model SWASH is compared to flume observations of infragravity waves propagating over a plane slope and barred beach. The experiments cover a range of infragravity wave conditions, including forcing by bichromatic and irregular waves, varying from strongly dissipative to strongly reflective, so that model performance can be assessed for a wide range of conditions. The predicted bulk wave parameters, such as wave height and mean wave period, are found to be in good agreement with the observations. Moreover, the model captures the observed breaking of infragravity waves. These results demonstrate that SWASH can be used to model the nearshore evolution of infragravity waves, including nonlinear interactions, dissipation and shoreline reflections.