| Mon July 7th 2008 16:00 HR C101 | Seminar | Numerical simulation of hydrodynamic wave loading Arthur Veldman |
Details:Extreme waves and their impact loading on fixed and floating structures,like production and offloading platforms, coastal protection systems and offshore wind farms, have long been subjects that could only be studied with experimental methods. The complex, highly non-linear wave kinematics could only globally be predicted with existing numerical CFD methods. However, recent research has shown that new hydrodynamic models based on the Navier--Stokes equations, in combination with a VOF-based method for the description of the free-surface dynamics, are making progress in predicting such effects. In close cooperation with MARIN (Wageningen), Deltares (Delft) and the offshore industry the development of these methods is pursued. Major applications are external flows like green-water loading on the deck of vessels and wave run-up against platforms, or internal flows like sloshing inside LNG tanks. Detailed experiments are available to validate the numerical simulations. During the method development, many numerical features had to be refined, related for instance to mass conservation and smoothness of the pressure signals. The current version of the method, called ComFLOW, contains a two-phase flow description to include the cushioning effects of entrapped air bubbles. Here the treatment of the density in computational cells near the free surface appeared to require special care: a so-called gravity-consistent averaging procedure has been designed. Although the literature on numerical simulation of free-surface flow is rapidly expanding, it is our experience that many numerical bits and pieces still require considerable improvement before the methods can be used for real-life applications. | ||
