Abstract
The disintegration phenomena of nonlinear wave train passing over a submerged dike have been investigated by a previously developed numerical model. The model, based on the time dependent boundary element method, employs an effective non reflective open boundary treatment and can be applied to arbitrary nonlinear wave processes. The computed wave profiles at various locations agree favorably with experimental observations. The numerical results indicate that the higher harmonics generated during the passage over the dike are transformed into prominent free waves in the trailing side of the dike, demonstrating the essential mechanism of the observed disintegration phenomenon. It is found that the amplitude of each higher frequency component is spatially modulated with the beat λ over the dike, and that the corresponding amplitude of transmitted wave becomes remarkably large when the width of the dike is nearly one half of λ. Furthermore, in the case of large incident waves, significant decomposition is found to occur even when the dike is deeply submerged.
