Parameterisation and transformation of wave asymmetries over a low-crested breakwater

Zhong Peng, Qingping Zou*, Dominic E. Reeve, Baoxing Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)
28 Downloads (Pure)


This paper presents the results of an investigation of the transformation of wave skewness and asymmetry as waves propagate obliquely over low-crested breakwaters, (LCBs), based on an analysis of measurements collected in the DELOS project. Considering the effect of the local Ursell number on wave asymmetries, a set of practical empirical formulae were established using least squares regression for both smooth and rubble mound LCBs. Predictions are in good agreement with measurements. Wave skewness on both sides of LCBs is linearly correlated for rubble mound LCBs but weakly correlated for smooth LCBs. While wave asymmetry on both sides of LCBs has a weakly quadratic correlation. The effect of the relative freeboard on the relationships of wave asymmetries between both sides is significant for rubble mound LCBs, but the same does not hold for smooth LCBs. With the presence of LCBs, wave skewness retains a positive sign on both sides but asymmetry changes from negative on the incident side to positive on the transmission side. Bispectral analysis shows that positive skewness and negative asymmetry arises from self-self and sum interactions but positive asymmetry is due to difference interactions between frequencies. The findings provide improved understanding of changes in wave skewness and asymmetry in the vicinity of structures, which may help mitigate scour and improve the stability of breakwaters. Crown

Original languageEnglish
Pages (from-to)1123-1132
Number of pages10
JournalCoastal Engineering
Issue number11-12
Publication statusPublished - Nov 2009


  • Asymmetry
  • Bispectrum
  • Low-crested breakwater
  • Nonlinearity
  • Skewness
  • Wave transformation

ASJC Scopus subject areas

  • Environmental Engineering
  • Ocean Engineering


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