Fluid•DTU seminar, 11:00 Tuesday, 09 December 2008, Bldg. 306 Aud. 33

This talk will be divided into four parts.

Part 1: Numerical computation of free-surface flows

During the past eight years, I have been working in collaboration with S. Grilli (University of Rhode Island) on the development of a fast numerical wave tank (NWT), which efficiently mimics laboratory wave tanks. A description of the NWT as well as several applications will be presented.

Part 2: Phenomena of dispersive waves

Analytical and asymptotic methods still have an essential role to play despite the dominant role played by numerical methods.Mathematical approaches for the study of waves in dispersive systems will be presented. Recently, we derived new systems of equations for the study of water waves in the presence of viscous dissipation.

Part 3: Tsunamis

The various numerical codes which are used throughout the world to compute the propagation of tsunamis across the oceans must be informed by initial conditions. It is shown that the classical approach, consisting of translating the frozen deformation of the sea bottom towards the free surface and letting it propagate, has some drawbacks.

Part 4: Violent flows

In the study of ocean wave impact on structures, one often uses Froude scaling since the dominant force is gravity. However the presence of trapped or entrained air in the water can significantly modify wave impacts. We propose a basic two-fluid model in which both fluids share the same velocities and analyze some of its properties. It is shown

that this model can be used to study violent aerated flows, especially by providing fast qualitative estimates.