A Detailed Investigation of Surf Zone Hydrodynamics using Smoothed Particle Hydrodynamics Simulations

The accurate prediction of wave transformation and breaking in the nearshore zone, including the impacts on coastal structures, still remains one of the great challenges in the fields of nearshore oceanography and coastal engineering. Much of this uncertainty stems from how to most accurately simulate the breaking process (i.e. overturning of the free surface), and in turn, how this triggers organized sea-swell waves to drive a broad range of other motions (e.g. from high-frequency surfzone turbulence to slowly-varying mean currents). To deal with breaking, conventional wave models depend heavily on simplifications of the breaking process (including empirical parameterization) that may not be broadly applicable to many coastal regions (including when assessing wave-structure interactions). While a range of computational fluid dynamics (CFD) models have been applied to simulate surfzone processes, they traditionally rely on solutions of the Navier-Stokes equations on a fixed grid that can struggle to resolve the rapidly-varying free surface deformations that occur during wave breaking.

In this study we apply a mesh-free (Lagrangian-based) Smoothed Particle Hydrodynamics (SPH) modelling approach initially investigate how accurately these models can predict a broad spectrum of hydrodynamic processes relevant to coastal applications where wave breaking is important. Using experimental data of regular and irregular wave breaking over both a beach and fringing reef profile, we demonstrate how the model can accurately reproduce and provide physical insight into a broad range of relevant hydrodynamic processes, ranging from the nonlinear evolution of wave shapes across the surfzone, wave setup distributions, mean current profiles and wave runup.