This paper describes the hydrodynamic characteristics of a pile-supported vertical wall breakwater, the upper part of which is a vertical wall, and the lower part consisting of an array of vertical piles. For regular waves, using the eigenfunction expansion method, a numerical model has been developed that can compute wave transmission, reflection, and run-up, and wave force acting on the breakwater. For irregular waves, the regular wave model is repeatedly used for each frequency component of the irregular wave spectrum. The wave period is determined according to the frequency of the component wave, while the root-mean-squared wave height is used for all the component waves to compute the energy dissipation between piles. To examine the validity of the developed models, large-scale laboratory experiments have been conducted for pile-supported vertical wall breakwaters with a constant spacing between piles but various drafts of the upper vertical wall. Comparisons between measurement and prediction show t...

Laboratory measurements of the instantaneous free surface, horizontal velocity, and void fraction fluctuations were made simultaneously for three cases of regular waves breaking on a plane slope. The data were reduced by ensemble averaging to quantify the temporal variation of the turbulence intensity and void fraction above trough level in the aeration region of the breaking waves. The cross-shore location of the measurements was restricted to the transition region marked by a rapid decrease in wave height. The study showed that the maximum ensemble-averaged void fractions were between 15 and 20% and that the temporal variation of the normalized void fraction above the still water level could be modeled by linear growth followed by exponential decay. The temporal variation of void fraction above the still water normalized by the wave period and average void fraction appears to be self-similar.

This paper presents optical measurements of debris movement and tsunami inundation over an unobstructed beach in a laboratory wave basin. The debris consisted of rectangular boxes and was placed unconstrained on a flat section raised above the basin floor with no still water on the raised section. Debris movement was measured using two overhead video cameras and a novel object-tracking algorithm. Two standard optical techniques, wave edge detection and particle image velocimetry, were used to compare optical and in situ measurements of fluid velocity. The debris motion (position, velocity) in the onshore direction was found to be repeatable, but the offshore motion varied between trials because of the irregular nature of the flow field during the return. For debris in free translation, as the number of debris specimens increased, the peak average velocity decreased and the onset of the peak was delayed in the onshore direction. In the offshore direction, the velocity was lower by a factor 4–6 and was independent of the quantity of debris. The decrease in the peak onshore velocity with increasing amount of debris was observed for debris that undergoes an initial rotation. The peak onshore velocity was nearly independent of whether the initial motion was purely translational or a combination of rotation and translation.