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Weekly Seminar: Spring 2008

Date: April 18
Time: 11:00 AM
Location: Maryland Hall 110
Speaker: Dr. Tim Janssen
Naval Postgraduate School
Title:"Nonlinear ocean waves across the continental shelf"

Abstract

As ocean wind waves propagate across the shelf from deep water onto beaches,
their nonlinearity transitions from a deep-water (Stokes) regime to a shallowwater
(Boussinesq) regime. The physics is distinct. Deep-water nonlinearity takes
place on relative long time and space scales and is linked, among others, to the
occurrence of extreme ocean waves, sometimes referred to as ‘freak’ or ‘rogue’
waves. Shallow-water nonlinearity on the other hand, results in transfer of energy
to harmonics and infragravity waves, which plays an important role in e.g. sand
bar migration and sediment transport. In this talk we will present new modeling
approaches to these nonlinear wave regimes and, on the basis of simulations
and observations, discuss their implications: 1) the contribution of nonlinearity to
‘freak’ wave events in realistic oceanic conditions and 2) the role of the wave
third-order moment in shoaling or dissipative wave conditions.