MEASUREMENTS OF SURF BEAT AND SET-DOWN BENEATH WAVE GROUPS

J.K. Kostense
1984 Coastal Engineering Proceedings  
A laboratory study was conducted to measure the amplitudes of long waves In shallow water as induced by wave grouping. In a 55 m long wave channel with a plane beach at the end, two primary waves of nearly equal frequency were generated. Due to a sophisticated control of the wave paddle - including second order wave generation as well as active wave absorption at the paddle face - the wave action at the difference frequency was limited to an incident forced wave, propagating at the group
more » ... y, and a reflected free wave generated in the surf zone. For the incident forced - or bound - wave, also known as set-down, the experimental results show good agreement with the existing theory. Furthermore, the experiments confirm qualitatively a theoretical model by Symonds et al. (198 2) explaining two-dimensional surf beat as a result of the time-varying breakpoint of the incident primary waves.
doi:10.9753/icce.v19.49 fatcat:5bh2luus7rcuvh4gsapx24dhhy