Performance of a new quasi-3D eddy viscosity model for plunging breaker

B. Ontowirjo, S. Rahman, A. Mano

Research output: Contribution to journalArticlepeer-review


Estimation of wave propagation in coastal region is essential for researchers. Ability to estimate this behavior affects the design of coastal structures as well as our ability to forecast beach profile evolution. The powerful plunging breakers are important contributor to turbulence, spray and bubble generation in the water column. Numerical models have been developed for simulating wave breaking in the surf zone. The Boussinesq-Type Equation (BTE) model has become an important tool in coastal engineering, especially in real-world applications where refraction and diffraction as well as nonlinear wave-wave interaction are important. The breaking phenomenon is predicted in two main approaches; surface roller and eddy viscosity. The basic idea behind the eddy viscosity model is the addition of a momentum diffusion term to the BTE with the diffusivity strongly localized on the front face of broken wave. The more recent eddy viscosity model of Kennedy et al. used a momentum-conserving eddy viscosity technique to model the initiation and cessation of wave breaking dissipation. The application of the strong localized diffusivity on the front face of wave is limited to breaking dissipation only, where as in reality the distribution of turbulent diffusivity is stretched along the propagating wave profile. In this study, a new eddy viscosity model to calculate the breaking wave dissipation and estimate realistic turbulent mixing is developed. The BTE in quasi-3D is utilized to simulate the flow field and turbulent mixing estimation. In contrast to the depth averaged eddy viscosity model which can only act locally on the front face of a broken wave, the proposed model of eddy viscosity may extend along the surf zone. Turbulent mixing is an important variable to determine the suspended sediment distribution along the beach profile evolution. Performance of the new eddy viscosity model under plunging breaker is examined through the comparison with the Smagorinsky model and experimental data. The comparison has been made for a cross-shore variation of phase averaged wave decay, free surface elevation, horizontal and vertical velocity. The good agreement between the previous and the new eddy viscosity model are presented.

Original languageEnglish
Pages (from-to)1145-1149
Number of pages5
JournalJournal of Coastal Research
Issue numberSPEC. ISSUE 64
Publication statusPublished - 2011 Dec 1


  • Eddy viscosity
  • Plunging breaker
  • Surf and swash zone

ASJC Scopus subject areas

  • Ecology
  • Water Science and Technology
  • Earth-Surface Processes


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