Individual violent wave-overtopping events: behaviour and estimation

Alison Raby*, Ravindra Jayaratne, Henrik Bredmose, Geoff Bullock

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

To better understand individual violent wave overtopping, of significance for coastal defence design, three breaking wave types (steep-fronted, plunging and broken) based on focused wave groups, were generated in laboratory and numerical models. High-speed video captured overtopping events and produced velocity vector maps by means of bubble image velocimetry (BIV). Results were compared with a numerical model based on a linear wave detection procedure and a two-phase incompressible Navier–Stokes-based solver. This novel approach revealed that the overtopping waves comprised an initial jet of 0.2 s duration, but dominated by quasi-steady flow. Whilst laboratory surface-elevation time-histories were highly repeatable, overtopping volume repeats were sensitive to the breaker type. Measured volumes were compared with: the numerical model (which over-predicted, but was reasonably accurate for steep-fronted waves); estimations based on BIV results (which provided very close agreement for the steep-fronted waves); and a weir-based analogy (which provided reasonable agreement, but always under-predicted).
Original languageEnglish
JournalJournal of Hydraulic Research
Volume58
Issue number1
Pages (from-to)34-46
Number of pages13
ISSN0022-1686
DOIs
Publication statusPublished - 2020

Bibliographical note

© 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Keywords

  • Breaking waves
  • Bubble image velocimetry
  • Coastal engineering
  • Flow visualization and imaging
  • Incompresible Navier-Stokes solver
  • Laboratory studies
  • Violent wave overtopping

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