hms + + : Open-source shallow water flow model with focus on investigating computational performance

An open-source high-performance program for the numerical simulation of surface water flow (hms++) is introduced. It contains a robust, explicit MUSCL solver for the shallow water equations (SWE). hms++provides a user- and HPC-friendly interface as well as a plugin mechanism for runtime extensibility. It is used in several research projects pertaining to surface water flow (urban flooding, model coupling with subsurface flow in drainage systems), and in teaching at TU Berlin, Germany. Using hms++, this contribution aims to find and evaluate ways to reduce computational cost of SWE solvers, by improving hardware utilisation. Results of this study indicate that using a cache-blocking structure for the time marching loop, and vectorisation of flux computations, leads to a speedup of around 30×.