Flow Depths and Velocities across a Smooth Dike Crest

Abstract

This contribution proposes a systematic analysis of the overtopping process at dikes, focused on the statistical description of the extreme flow characteristics across the dike crest. The specific objective of the analysis is the investigation of structures subjected to high run-up levels and low freeboards, under severe or extreme conditions that are likely to occur in the future due to climate change. The adopted methodology is based on the collection of new experimental and numerical tests of wave overtopping at smooth dikes at various crest levels. The reliability of the new data is checked in terms of average overtopping discharge and wave reflection coefficient, against consolidated predicting methods from the literature. An update and refitting of the existing formulae for the prediction of the extreme flow depths and velocities at the dike off-shore edge is proposed based on the experimental and numerical outcomes. The dynamics of the overtopping flow propagation along the dike crest under breaking and non-breaking waves, in emerged and submerged conditions, is investigated. Guidelines to update the state-of-the-art formulae for a more cautious estimation of the water depths and the velocities of propagation of the flow in the landward area are provided.

Non-Intrusive Measurements of Wave-Induced Flow over Dikes by Means of a Combined Ultrasound Doppler Velocimetry and Videography

“…The analysis of the results in terms of reflection coefficients and overtopping rates was presented in [41], where a good agreement of the experimental data with most widely used formulae was shown together with proposed guidelines to update the state-of-the-art formulae for a more cautious estimation of the water depths and velocities of propagation of the flow in the landward area.…”

“…New experiments on wave overtopping at dikes have been carried out at the University of Bologna in the wave flume depicted in Figure 1. This is 12 m long, 0.5 m wide and 1.0 m deep, and waves are generated by the vertical movement of a cuneiform-shaped piston-type wave-maker defined on the basis of mass conservation law [39,40] and described in detail by [41]. The generated irregular waves were characterized by values of significant wave height H s in the range 0.04-0.06 m and peak wave periods T p in the range 0.85-1.51 s, with corresponding values of the wave steepness s m−1,0 = H s /L m−1,0 ≈ 0.03-0.04.…”

“…The presented image processing was also applied to estimate the wave front propagation over the dike crest and reconstruct the maximum and mean water depth envelopes, as shown in [41].…”

“…where γ b , γ ν , γ f , and γ β are the influence factors for a berm, roughness elements on a slope, a crest wall, and oblique wave attacks; in this paper, all these factors are equal to 1, also according to [41].…”

Implementation and Validation of a Potential Model for a Moored Floating Cylinder under Waves

“…The new experiments on floating body dynamics under waves were carried out in the wave flume of the University of Bologna. The flume, sketched in Figure 1, is 12 m long, 0.5 m wide and 1.0 m deep, and the waves are generated on the left-hand side by the vertical movement of a cuneiform-shaped piston-type wave-maker [31,32]. On the other side of the channel, a wave absorber panel is installed to reduce the wave reflection.…”