Irregular Breaking Wave Transmission over Submerged Porous Breakwater

Abstract

A numerical model based on time-averaged continuity, momentum, and energy equations is developed to predict the mean and standard deviation of the free surface elevation and horizontal fluid velocities above and inside a porous submerged breakwater. The energy dissipation rate due to irregular breaking waves is estimated using an existing formula that is modified for intense wave breaking on the steep seaward slope of the breakwater. This computationally efficient numerical model is an extension of the existing time-averaged model which is widely used to predict irregular breaking wave transformation on impermeable beaches. The developed model is shown to predict the cross-shore variations of the mean and standard deviation of the free surface elevation measured in a laboratory experiment where a submerged porous breakwater was placed on a gentle impermeable slope. The agreement for the measured horizontal velocity is marginal partly because this one-dimensional model does not predict the vertical velocity variation. This semiempirical model calibrated using the present experiment will need to be compared with additional experiments.