WATER-WAVES ON CROWN BREAKWATERS

The linear theory for waves impinging obliquely on a vertical, porous breakwater with an impermeable crown is examined. The wave-induced flow within the breakwater is modeled by the 1972 theory of Sollitt and Cross. Using eigen-function expansions for the velocity potentials seaward of the breakwater, beneath the crown, and behind the structure, the reflection and transmission coefficients are calculated to determine the sheltering provided by the breakwater. The results agree well with other methods, including a plane wave analysis. obtained by neglecting the evanescent wave modes. The distribution of the wave-induced pressure along the base of the crown is also calculated, showing that the linear pressure gradient assumption usually applied for uplift forces on the breakwater crown is inaccurate.