Wave deformation and vortex generation in water waves propagating over a submerged dike

The Navier-Stokes equations and the exact free surface boundary conditions are solved to simulate wave deformation and vortex generation in water waves propagating over a submerged dike. Incident waves are generated by a piston-type wavemaker set up in the computational domain. Numerical results are compared with experimental data in order to confirm the validity of the numerical model. The fast Fourier transform and a wave resolution technique are applied to decompose the transformed waves and the higher harmonics. Effects of different parameters on wave transformation and vortex generation are studied systematically. These parameters include the Ursell number, the Keulegan-Carpenter number, the water depth ratio, the Reynolds number, the length aspect ratio of the dike, and the type of dike. (C) 1999 Elsevier Science B.V. All rights reserved.