Abstract
Change of wave overtopping rate with increase of wave period is studied experimentally, first, by using sinusoidal incident waves. It is found that the rate does not increase monotonically. The second-order free waves are generated at wave maker when sinusoidal signal is used in shallow water. Phase difference between the primary waves and the second-order free waves at dike varies with wave period, introducing large variation of peak height of waves and overtopping rate accordingly. The rate increases monotonically when cnoidal waves are generated.
