From the surface to the sea bed:

The seminar will present highlights of the presenter’s coastal hydrodynamics research spanning the past decade, with focus on two fronts: 1) computational wave hydrodynamics and 2) numerical simulation of sediment transport processes and scour. Results involving simulated nonlinear water waves will first be presented, based on a developed highly-accurate “Boussinesq-type” approach. The developed wave model is capable of simulating a wide range of physical scales, and this flexibility will be demonstrated through applications ranging from extreme waves in deep water to shallow-water tsunami propagation and run-up at the shoreline. Results considering the life cycle of a typical tsunami prior to run-up will be considered in detail, including propagation over a deep ocean floor, shoaling up a continental slope, and finally nearshore propagation on a continental shelf region. Analysis of the results will reveal significant shortcomings regarding the use of so-called solitary waves as model tsunamis, which has been the dominant paradigm for experimental and mathematical research on tsunamis dating back to the 1970s. Research involving sediment transport and scour will then be presented, based on a developed “fully-coupled” simulation tool, in which hydrodynamics, turbulence, and sediment transport (bed and suspended load) descriptions are combined to drive resultant morphology of the sea bed. Results from a recent study involving the simulation of scour beneath submarine pipelines in combined wave-plus-current flow environments will be presented. Through systematic application and analysis of a large number of runs, a new and simple expression for the time scale of scour is developed, which is presently lacking in the literature. The new generalized expression unifies those previously proposed for both the pure-wave and pure-current limits, and is appropriate for engineering use.