Surf zone wave overtopping a trapezoidal structure: 1-D modelling and PIV comparison

Experiments have been undertaken on surf zone waves, with a surf similarity parameter of about 0.3, overtopping a trapezoidal obstacle with 1:2 side slopes, on a beach of 1:20 slope. Particle image velocimetry (PIV) investigation has shown complex vortical structures resulting from shoreward propagating bores interacting/colliding with bores partially reflected from the obstacle, before overtopping the obstacle. A 1-D depth-averaged shallow-water model captures qualitatively much of the wave dynamics. However, the marked turbulent air entrainment in the collision zone appears significant in raising mean water level relative to the model and causing a phase lag in the model relative to the experiment. Peak overtopping levels are overpredicted by about 100% with this phase lag. © 2004 Elsevier B.V. All rights reserved.