Propagation of solitary waves over double submerged barriers

Abstract

Protection of nearshore area by means of artificial structure is an important issue for coastal engineering community. In this study, we aim to investigate wave hydrodynamics and hydrodynamic performance due to solitary waves interacting with double submerged barriers. Double barriers, put bottom-mounted vertically on the flat seafloor and also paralleled to each other, are considered as a wave absorber. New experiments are carried out to provide measured data for model validation. Numerical simulations are performed using a depth- and phase-resolving model, based on the Reynolds-Averaged Navier-Stokes equations with a non-linear k-ε turbulence closure model. Model-data comparisons show good agreements in terms of free surface fluctuations in time histories and error analyses are performed. Numerical results are then used to study the variations of the free surface motions of breaking waves and the flow fields. In particular, the model results reveal that the optimal horizontal distance, judged as minimum wave transmission, between two submerged barriers is approximately 2.5 times the still water depth for present wave conditions and obstacle geometries. Furthermore, numerical model is extended to evaluate the functional efficiency of a dual-slotted-barrier system with different obstacle configurations under various conditions of solitary waves by means of energy reflection, transmission and dissipation coefficients.