This study generalizes SWAN model capabilities for free infragravity (IG) waves based on a new collection of measurements over the southern part of the North Sea. As a first step, existing SWAN model capabilities for free IG are generalized to unstructured grids. In contrast to the common nesting approach, unstructured grids reduce modelling complexity through the use of a single computational grid that allows local refinement nearshore and high flexibility to generate grids along coastlines. The new collection of measurements provides a unique opportunity to validate this modelling approach over the spectral domain and over the full IG frequency band. Moreover, these new measurements enable model validation for both deeper water offshore-sites and shallower nearshore-sites and allow to optimize modelling performance for North Sea forecasting.
