Anastasios S. Metallinos

A simple model for predicting the vertical distribution of wave-induced pore pressures inside submerged porous structures is presented. A Boussinesq-type model coupled with a Darcy–Forchheimer equation was used to derive depth-averaged velocities. Then their profile was obtained by a semi-empirical approach based on energy considerations applied on a vertical distribution of the particle velocities induced by nonlinear waves in a free field. Laboratory measurements of hydrodynamic pressures were undertaken in a flume for breaking and non-breaking regular waves. The proposed model was compared with these measurements and to the results of a Reynolds Averaged Navier–Stokes equations model. Good agreement of the proposed model with the experiments was found and very good behaviour when compared with the RANS code. Increased pore pressures were identified during the experiments close to the downstream slope of the mound and a tendency of the pressures to increase with wave steepness. These effects were satisfactorily captured by the model.

A simple model for predicting the vertical distribution of wave-induced horizontal orbital velocities inside submerged porous structures is presented. A velocity profile is formulated based on the exponential profile of the nonlinear wave theory. This velocity distribution is then fitted to the numerically-predicted depth-integrated velocity given by a Boussinesq model assuming uniform porosity. For the sake of comparison, experimental measurements of horizontal velocities were taken in a laboratory flume. The proposed model was also compared with the results of a version of the commercial program FLOW-3D dealing with linear waves in a simple manner. A good agreement of the model results with the experiments was found as well as an improved behaviour with respect to this program. Moreover, increased velocities were identified at the downstream slope of the rubble mound caused by recirculating flow.