Wave-structure interaction using coupled structured-unstructured finite element meshes

The interaction of inviscid gravity waves with submerged fixed horizontal structures is modelled in two-dimensions using a finite element numerical wave tank. An adaptive hybrid coupled mesh is utilised that tracks the free surface through vertical movement of the free surface nodes in a Lagrange - Eulerian scheme. The hybrid mesh consists of a combination of structured and Voronoi unstructured meshes, with the submerged structure located in the Voronoi mesh region. Validation tests include free and forced sloshing in a rectangular tank, regular progressive wave propagation in a flume, and regular wave loading on a horizontal cylinder. The results are found to be in close agreement with analytical potential theory solutions for waves of small amplitude. Non-linear effects are noted for steeper waves. The wave-induced force components on the horizontal cylinder match the expected results from Ogilvie's [J Fluid Mech 16 (1963) 451] linear theory and Vada's [J Fluid Mech 174 (1987) 23] second order model. Wave interactions with a pair of submerged horizontal cylinders spaced at half the wavelength of undisturbed regular waves are examined. (C) 2003 Elsevier Ltd. All rights reserved.