Prediction of the displacement of large rocks by waves using smoothed-particle hydrodynamics

Breaking waves exert loads on ships, offshore structures, coastal infrastructure, and the coastline. A spectacular illustration of such loads in nature is the displacement of heavy boulders by storm waves. The field of coastal boulder dynamics has been steadily growing in recent decades. Here, the loads of breaking waves in various breaking stages are simulated using smoothed-particle hydrodynamics (SPH). Two different SPH solvers are used for numerical simulations, namely DualSPHysics and IMsPhACT, a bespoke multiphase SPH solver. The numerical simulations are set up to mimic laboratory experiments where the breaking wave induced pressure, accelerations and boulder displacement were measured. The effect of SPH parameters on the generated boulder loads is analysed. Moreover, multifluid simulations are conducted and compared against the monofluid simulations. Two-dimensional SPH simulations capture the main trends of wave-induced forces and of the displacement of the boulder. Moreover, while the absence of the gas phase alters the wave load, the overall boulder displacement is dominated by the sustained impact, where compressibility effects are of secondary importance.