  In this study we investigated the capabilities of the mesh-free, Lagrangian
particle method (Smoothed Particle Hydrodynamics, SPH) to simulate the detailed
hydrodynamic processes generated by both spilling and plunging breaking waves
within the surf zone. The weakly-compressible SPH code DualSPHysics was applied
to simulate wave breaking over two distinct bathymetric profiles (a plane beach
and fringing reef) and compared to experimental flume measurements of waves,
flows, and mean water levels. Despite the simulations spanning very different
wave breaking conditions (including an extreme case with violently plunging
waves on an effectively dry reef slope), the model was able to reproduce a wide
range of relevant surf zone hydrodynamic processes using a fixed set of
numerical parameters. This included accurate predictions of the nonlinear
evolution of wave shapes (e.g., asymmetry and skewness properties), rates of
wave dissipation within the surf zone, and wave setup distributions. By using
this mesh-free approach, the model was able to resolve the critical crest
region within the breaking waves, which provided robust predictions of the
wave-induced mass fluxes within the surf zone responsible for the undertow.
Within this breaking crest region, the model results capture how the potential
energy of the organized wave motion is initially converted to kinetic energy
and then dissipated, which reproduces the distribution of wave forces
responsible for wave setup generation across the surf zone. Overall, the
results reveal how the mesh-free SPH approach can accurately reproduce the
detailed wave breaking processes with comparable skill to state-of-the-art
mesh-based Computational Fluid Dynamics (CFD) models, and thus can be applied
to provide valuable new physical insight into surf zone dynamics.
