Boussinesq Modeling of Alongshore Swash Zone Currents

The study involves theoretical formulation, model development and verification, and integration with field observations of swash motions. The starting point of the theoretical formulation is the Euler equation of motion for waves and currents above the permeable seabed and the locally-averaged Navier-Stokes equations for the flow inside the porous layer. A complete set of fully nonlinear Boussinesq-type equations for waves and currents over a permeable beach is developed. Particular attention is paid to the conservation property of potential vorticity and the poor performance of preexisting equations when the ratio of the porous layer thickness to the water depth is large. Stokes-type analyses are carried out to examine the dispersion and damping properties of the new set of equations.