Numerical investigation of the instability and nonlinear evolution of narrow-band directional ocean waves

Bengt Eliasson, Padma Shukla

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The instability and nonlinear evolution of directional ocean waves is investigated numerically by means of simulations of the governing kinetic equation for narrow-band surface waves. Our simulation results reveal the onset of the modulational instability for long-crested wave trains, which agrees well with recent large-scale experiments in wave basins, where it was found that narrower directional spectra lead to self-focusing of ocean waves and an enhanced probability of extreme events. We find that the modulational instability is nonlinearly saturated by a broadening of the wave spectrum, which leads to the stabilization of the water-wave system. Applications of our results to other fields of physics, such as nonlinear optics and plasma physics, are discussed.
Original languageEnglish
Article number014501
Number of pages4
JournalPhysical Review Letters
Issue number1
Publication statusPublished - 30 Jun 2010


  • directional ocean waves
  • kinetic equation
  • narrow band surface waves

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