Practical estimation of wave transmission and reflection from fixed submerged structures

A numerical wave model (CADMAS-SURF) was used to estimate regular wave transmission and reflection from a fixed squared submerged structure placed at a distance above the seabed. A series of numerical experiments were performed varying relevant non-dimensional parameters such as ratio of water depth to wavelength, wave steepness, ratio of incident wave height to size of the structure, and ratio of obstacle freeboard to water depth. Each parameter has a different effect on the wave–structure interaction, and it is described in this study. Wave transmission and reflection are approximated in terms of two parametric equations, whose coefficients are estimated through regression analysis. It was found that both formulations seem to be accurate regardless of using parameter values that fall in or outside the range in which the equations have been inferred. Further studies with irregular waves varying the direction of wave propagation are recommended to extend the applicability range of the proposed formulae. Results from the proposed equations suggest that the required size of breakwater is at least five and 2.4 times the wave height for deep and shallow waters, respectively, in order to have transmission below 0.65 at seas with predominant wave steepness of 0.025 or higher.

► The contributions of several non-dimensional parameters relating water depth, wave and obstacle properties in wave transmission and reflection are described.
► Two parametric equations to find wave transmission and reflection from fixed submerged squared obstacles have been proposed.
► Obstacle efficiency is evaluated, describing its performance with nomograms developed in this study.