Importance of second-order wave generation for focused wave group run-up and overtopping.

Jana Orszaghova, Paul Taylor, Alistair Borthwick, Alison Raby

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Background
Focused wave groups offer a means for coastal engineers to determine extreme run-up and overtopping events.

Research purpose
This work examines numerically the importance of second-order accurate laboratory wave generation for NewWave-type focused wave groups generated by a piston-type paddle generator, and interacting with a plane beach and a seawall in a wave basin.

Methods
The numerical wave tank is based on the Boussinesq equations for non-breaking waves, and the non-linear shallow water equations for broken waves. During the model validation, good agreement is achieved between the numerical predictions and laboratory measurements of free surface elevation, run-up distances and overtopping volumes for the test cases driven by linear paddle signals. Errors in run-up distance and overtopping volume, arising from linear wave generation, are then assessed numerically by repeating the test cases using second-order accurate paddle signals.

Results
Focused wave groups generated using first-order wave-maker theory are found to be substantially contaminated by a preceding long error wave, resulting in erroneously enhanced run-up distances and overtopping volumes.

Conclusions
Thus, the use of second-order wave-maker theory for wave group run-up and overtopping experiments is instead recommended.
Original languageEnglish
Pages (from-to)63-79
Number of pages17
JournalCoastal Engineering
Volume94
Early online date26 Sept 2014
DOIs
Publication statusPublished - Dec 2014

Keywords / Materials (for Non-textual outputs)

  • wave-maker theory
  • spurious error wave
  • run-up
  • Overtopping
  • focused wave groups
  • Boussinesq numerical wave tank

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