Wave Statistics and Energy Dissipation of Breaking Waves Generated by a Wave Plate

TL;DR

This study uses direct numerical simulations to analyze breaking wave dynamics generated by a wave plate, examining energy dissipation, air entrainment, and the influence of initial conditions and surface tension on breaking features.

Contribution

It introduces a detailed numerical analysis of wave breaking, linking initial wave conditions and surface tension effects to breaking behavior and energy dissipation.

Findings

Good agreement between simulations and experiments on wave profiles and energy.

Wave breaking type correlates with the ratio of wave height to water depth.

Energy dissipation scales with initial conditions and local crest geometry.

Abstract

The present study focuses on direct numerical simulations of breaking waves generated by a wave plate at constant water depths. The aim is to quantify the dynamics and kinematics in the breaking process, together with the air entrainment and energy dissipation due to breaking. Good agreement is achieved between numerical and experimental results in terms of free-surface profiles, energy budget, and bubble statistics during wave breaking. A parametric study was conducted to examine the effects of wave properties and initial conditions on breaking features. According to research on the Bond number ($Bo$, the ratio of gravitational to surface tension forces), a larger surface tension produces more significant parasitic capillaries at the forward face of the wave profile and a thicker plunging jet, which causes a delayed breaking time and is tightly correlated with the main cavity size. A close relationship between wave statistics and the initial conditions of the wave plate is discovered, showing that breaker types can be classified according to the ratio of wave height to water depth, $H/d$. Moreover, the energy dissipation rate due to breaking can be related to the initial conditions of the wave plate by applying the conventional dissipation scaling of turbulence theory, and further correlated with the local breaking crest geometry using inertial-scaling arguments. The proposed scaling of the dissipation rate during the active breaking period is found to be in good agreement with our numerical results.