Runup and Rundown of Solitary Waves on Sloping Beaches

TLDR

The paper presents a combined experimental and numerical effort to study solitary wave runup and rundown on beaches. The study uses a two‑dimensional numerical model that resolves mean flow and turbulence to investigate both nonbreaking and breaking solitary waves, validating the model against experiments and boundary‑integral results and analyzing velocity fields and turbulence distributions. The model shows that flow patterns during runup and rundown exhibit large vertical variations in horizontal velocity, challenging shallow‑water approximations, and that for breaking waves on mild slopes it outperforms depth‑averaged equations while providing detailed velocity and turbulence distributions.

Abstract

This paper presents a combined experimental and numerical effort to study solitary wave runup and rundown on beaches. Both nonbreaking and breaking solitary waves are investigated. A two-dimensional numerical model that solves both mean flow and turbulence is employed in this study. For the nonbreaking solitary wave on a steep slope, numerical results of the present model are verified by experimental data and numerical results obtained from the boundary integral equation method model, in terms of both velocity distribution and free surface profiles. The characteristics of flow patterns during runup and rundown phases are discussed. The vertical variations of the horizontal velocity component are large at some instances, implying that the shallow water approximation may be inaccurate even for the nonbreaking wave runup and rundown. For the breaking solitary wave on a mild slope, numerical results of the present model are compared with experimental data for free surface displacements. The present model is found to be more accurate than the depth-averaged equations models. Using this numerical model, the mean velocity field and turbulence distribution under the breaking wave are discussed.