Kinematics of 2-d transient water waves using laser doppler anemometry

Results of recent research on experimental investigation of wave-fluid particle kinematics just prior to breaking using laser Doppler anemometry are presented. Extreme transient waves, similar to those found in hurricane Camille, and an 'equivalent' regular wave, often used for design purposes, are generated and their kinematics measured. The kinematics of transient waves of smaller height are also measured to evaluate the effect of wave height, and these data are compared to Stokes third-order theory. Due to particular asymmetries not present in the large regular symmetric wave, the transient wave kinematics under the crest are shown to be much more severe above the still water level and somewhat less severe below. The stretching method used for the simulated transient wave underestimates the horizontal velocities in the crest and overestimates them below the still water level. These comparisons suggest that it would be worthwhile to further investigate the use of extreme waves as more realistic design waves and to develop a wave theory that accounts for the effect of the asymmetries.