Regular and Irregular Waves on a Sloping Beach

Taking into account that many coastal processes, such as undertow currents, sedi-ment transport and action on maritime structures, are greatly affected by wave behav-iour, the aim of this paper is to investigate the hydrodynamics of both regular and irreg-ular waves. Hence, it illustrates the results of an experimental research carried out in two different laboratory wave flumes of the Water Engineering and Chemistry Depart-ment of Bari Technical University (Italy). The first laboratory experiment examines the hydrodynamics of three different regular waves breaking on a fixed sloping bottom. The principal interest is therefore fo-cused on the wave behaviour in the surf zone. The second experiment refers to an irregular wave characterized by a narrow banded spectrum and developing on a sloping sand bottom, in intermediate waters up to the surf zone. In this case, the shoaling region is thoroughly investigated in order to understand how the wave is affected by breaking induced turbulence. In both experiments, the phase-averaging technique is used to extract the turbulent component from the time series of the acquired signal. This procedure is routinely used in laboratory studies when regular waves are studied. On the contrary, for irregular waves, it is not always assumed, being feasible only when some specific rules are re-spected, as occurred in the present study. The analysis focused on the vertical profiles of time-averaged orbital velocities, wave and turbulent cross-correlations, turbulent kinetic energy, turbulent intensities. At the same time also the phase-averaged velocity components and turbulent kinetic energy were considered. Finally some considerations were derived for the transport of both turbulent kinetic energy and sediments, at various depths of each investigated location.