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 flo w within the breakwater is modeled by the 1972 theory of Sollitt and C ross. Using eigen-function expansions for the velocity potentials seaw ard of the breakwater, beneath the crown, and behind the structure, th e reflection and transmission coefficients are calculated to determine the sheltering provided by the breakwater. The results agree well wit h other methods, including a plane wave analysis. obtained by neglecti ng the evanescent wave modes. The distribution of the wave-induced pre ssure 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.