Titulo: Explosive ripple instability as waves break on the beach
Palestrante: Alexei A. Mailybaev (IMPA, Rio de Janeiro)
Local: Sala C-116
Resumo: We study the dynamics of small wavetrains propagating in the background of a steepening nonlinear wave. This can be seen as a model for small ripples developing on the slopes of breaking waves in the surf zone. Using the concept of wave action as an adiabatic invariant, we derive an explicit asymptotic expression for the change of ripple steepness. We show that strong compression near the tip on the wave leads to an explosive ripple instability. This instability may play an important role in the understanding of fragmentation and whitecapping at the surface of breaking waves. Analytical results are confirmed by numerical simulations using a potential theory model. This is a joint work with André Nachbin.