SWASH: An operational public domain code for simulating wave fields and rapidly varied flows in coastal waters

A computational procedure has been developed for simulating non-hydrostatic, free-surface, rotational flows in one and two horizontal dimensions. Its implementation in the publicly available SWASH (an acronym of Simulating WAves till SHore) is intended to be used for predicting transformation of surface waves and rapidly varied shallow water flows in coastal waters. This open source code (http://swash.sourceforge.net) has been developed based on the work of Stelling and Zijlema, 2003, Stelling and Duinmeijer, 2003, Zijlema and Stelling, 2005 and Zijlema and Stelling, 2008). The governing equations are the nonlinear shallow water equations including non-hydrostatic pressure and provide a general basis for describing complex changes to rapidly varied flows typically found in coastal flooding resulting from e.g. dike breaks and tsunamis, and wave transformation in both surf and swash zones due to nonlinear wave–wave interactions, interaction of waves with currents, and wave breaking as well as runup at the shoreline. The present paper provides a complete description of the numerical algorithms currently used in the code. The code is benchmarked using some analytical problems. Moreover, the numerical results are validated with various cases of laboratory data with the principal aim to convey the capabilities of the SWASH code. In particular, emphasis is put on an analysis of model performance and associated physical implications. Serial and parallel performance scalings are also presented.