Author(s): Victor Loras-Herrero; Pablo Valles; Jannik Kuehn; Nikola Danglade; Matthias Delpey; Volker Roeber

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Keywords: Boussinesq modelling; Coastal hazards; GPU acceleration; High-performance computing; Performance portability; Wave-resolving simulations

Abstract: Boussinesq-type models (BTMs) are widely used for simulating nearshore processes such as nonlinear shoaling, wave breaking and surf-zone currents. Their phase-resolving accuracy makes them well suited to predict runup during storm events, wave–current interactions, and pollutant dispersion. However, the high computational cost of 2D BTMs has so far limited their use in operational forecasting. Recent GPU-based implementations have shown the benefits of hardware acceleration, but most remain tied to specific platforms and lack performance portability. This work extends BOSZ, a phase-resolving Boussinesq solver, to the Kokkos C++ performance portability framework. BOSZ employs an efficient staggered finite-difference scheme and now runs seamlessly across CPUs, GPUs, and next-generation HPC systems from a single code base. Preliminary benchmarks demonstrate speedups of 3–4× on CPUs with respect to the previous existing OpenMP version; and up to 25–30× on GPUs for large coastal domains, enabling simulations with millions of grid cells to complete within hours instead of days. These advances make high-resolution, faster-than-real-time simulations of kilometer-scale coastal segments feasible.

DOI:

Year: 2026