On the Choice of Random Wave Simulation in the Surf Zone Processes

Abstract

In this paper, the two common approaches to account for wave randomness, the spectral approach and the wave-bywave approach, are compared through numerical experiments conducted with the coupling of a surf zone hydrodynamic model and a bedload sediment transport model. Special attention is paid to the wave nonlinearity and net cross-shore bedload transport predictions. The two approaches are found to have negligible difference in their predictions of certain average hydrodynamics, such as wave heights, set-up and undertow. However, the wave-bywave approach outperforms the spectral approach in the wave nonlinearity prediction, and the two approaches differ significantly in their predictions of wave-induced net cross-shore bedload transport which strongly depends on wave nonlinearity. This suggests the necessity of using the wave-by-wave approach. The computational efficiency of the wave-by-wave approach is also discussed.

Turbulent boundary layers under irregular waves and currents: Experiments and the equivalent‐wave concept

“…For the probabilistic approach, irregular waves are treated as a package of independent periodic waves following a specified probability distribution, e.g., Dally [], Grasmeijer and Ruessink [], and Yuan and Madsen []. Therefore, the existing models for periodic WCBL can be directly applied for individual periodic waves to obtain the probability distributions for certain variables of interest, e.g., maximum wave bottom shear stress [ Myrhaug et al ., ], or some deterministic physical quantities through probabilistically averaging, e.g., current velocity [ Yuan and Madsen , ]. The fundamental drawback of this approach is that some physical processes, e.g., boundary layer streaming, may not have immediate response to the change of wave conditions, so it is questionable to assume that individual waves are totally independent.…”