GAFD Seminar: Tom Bridges (University of Surrey)

A theory for breaking of three-dimensional water waves in deep water is presented.  The starting point is a class of large-amplitude 3D waves of the full equations, computed numerically. These waves are unstable with an eigenfunction that is localised near peaks and creates an overturning shape, when added to the basic state.  Studying the 3D problem numerically, using a CFD code for the full Navier-Stokes equations with weak viscosity, shows that the waves do indeed overturn, generating a microbreaker, similar to what has been observed in the open ocean. The variability and robustness of this mechanism are discussed: diversity of the class of basic states; drivers of crest instability and diversity of the shape of instability; robustness of the mechanism to real world perturbations.