Effects of following and opposing vertical current shear on nonlinear wave interactions

Haifei Chen, Qingping Zou

Research output: Contribution to journalArticle

Abstract

A Navier-Stokes solver in OpenFOAM ® is combined with the Volume of Fluid (VOF) surface capturing method to investigate the wave interaction with depth-varying currents in intermediate and shallow waters. A special attention is paid to the separate effect of vertical current shear on near resonant triad wave interactions. It was found that in the presence of following vertical current shear, the wave exhibits a sharper crest and flatter trough, and the opposite is true in the presence of opposing vertical current shear. Our model results indicate that the wave steepness at which the current shear starts to affect the crest elevation is greater in deeper water than in shallower water. We found that adding vertical current shear to the uniform current further enhances the relative harmonic wave energy and the extent of triad interaction in the following current while weakens them in the opposing current. As a result, following and opposing current shear may cause wave to break at a lower and higher sea state respectively. Due to the increased wave nonlinearity in the presence of a following current shear, a linear superposition of the individual wave and current velocities is no longer adequate to represent the total horizontal velocity close to the free surface.

LanguageEnglish
Pages23-35
Number of pages13
JournalApplied Ocean Research
Volume89
Early online date18 May 2019
DOIs
Publication statusPublished - 1 Aug 2019

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Water
Fluids

Keywords

  • Harmonic generation
  • OpenFOAM
  • Opposing current
  • Triad interaction
  • Vertical current shear
  • Wave asymmetry
  • Wave skewness
  • Wave-current interaction

ASJC Scopus subject areas

  • Ocean Engineering

Cite this

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title = "Effects of following and opposing vertical current shear on nonlinear wave interactions",
abstract = "A Navier-Stokes solver in OpenFOAM {\circledR} is combined with the Volume of Fluid (VOF) surface capturing method to investigate the wave interaction with depth-varying currents in intermediate and shallow waters. A special attention is paid to the separate effect of vertical current shear on near resonant triad wave interactions. It was found that in the presence of following vertical current shear, the wave exhibits a sharper crest and flatter trough, and the opposite is true in the presence of opposing vertical current shear. Our model results indicate that the wave steepness at which the current shear starts to affect the crest elevation is greater in deeper water than in shallower water. We found that adding vertical current shear to the uniform current further enhances the relative harmonic wave energy and the extent of triad interaction in the following current while weakens them in the opposing current. As a result, following and opposing current shear may cause wave to break at a lower and higher sea state respectively. Due to the increased wave nonlinearity in the presence of a following current shear, a linear superposition of the individual wave and current velocities is no longer adequate to represent the total horizontal velocity close to the free surface.",
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Effects of following and opposing vertical current shear on nonlinear wave interactions. / Chen, Haifei; Zou, Qingping.

In: Applied Ocean Research, Vol. 89, 01.08.2019, p. 23-35.

Research output: Contribution to journalArticle

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AU - Zou, Qingping

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