Wave Effect on Slotted Breakwaters Considering Evanescent Modes

The present paper outlines the numerical calculation of wave runup, maximum horizontal wave force on the breakwater and maximum overturning moment on the slotted breakwater. For regular waves, using eigenfunction expansion method, a numerical model is developed that can compute wave transmission coefficient, wave reflection coefficient, and runup and wave force and its related momentum acting on the breakwater. To examine validity of the developed models, experimental measurements of Isaacson (1998) are compared with numerical results. Comparisons between measured and predicted values show that the mathematical model is able to adequately reproduce most of the important features of the experimental results. Wave runup and maximum horizontal wave force decreases by increasing porosity. As the relative water depth increases, wave runup and wave force decreases with respect to an impermeable breakwater. On the other hand, decreasing of relative draft, leads to much more reduction of relative wave force and runup with respect to impermeable one.