Random Wave Run-up with a Physically-based Lagrangian Shoreline Model

AbstractIn the present paper the run-up of random waves was calculated by means of a numerical method. In situ measurements based on a video imaging technique have been used for the validation of the present numerical model. The on-site run-up measurements have been carried out at Lido Signorino beach, near Marsala, Italy,along a transect, normal to the shore. A video camera and a linear array of rods have been used to obtain field data. Numerical simulations with a 1DH Boussinesq-type of model for breaking waves which takes into account the wave run-up by means of a Lagrangian shoreline model have been carried out. In such simulations random waves of given spectrum have been propagated in a numerical flume having the same beach slope of the measured transect. The comparison between registered and estimated run-up underlined an acceptable agreement. Indeed, the numerical model tends to underestimate the actual R2%, with the maximum underestimate being less than 24%, which is a reasonable error in many cases of engineering interest

Waves plus currents crossing at right angle:experimental investigation

The hydrodynamics generated by a regular wave field perpendicularly superimposed to a steady current is investigated by means of laboratory experiments. The flow structure is analyzed by measuring the velocity profiles using a micro Acoustic Doppler Velocimeter. Three cases are considered: current only, waves only and waves plus current. Different bottom roughnesses are used, and the apparent roughness ks is estimated for each condition. In the presence of a small roughness, the superposition of the waves on the current causes an increase of the current velocities close to the bottom, thus generating a decrease of the apparent roughness with respect to the case of the current only. On the other hand, when a large bottom roughness is present, the waves force a decrease of the current velocity close to the bottom and, in turn, an increase of the apparent bottom roughness. Such a behavior seems related not only to the roughness but also to the flow regime (i.e., laminar or turbulent) within the wave bottom boundary layer

Boussinesq modeling of breaking waves: Description of turbulence

Improved turbulent closures for use in fully nonlinear Boussinesq-type models are described here. The approach extends previous works in order to give a more flexible and accurate description of the turbulence due to a breaking wave. Turbulent stresses are handled by means of the Boussinesq hypothesis, and the eddy viscosity is assumed to vary over the water depth according to different laws. The model is described in detail, and its performances are evaluated both against available analytical solutions and against experimental data of regular waves breaking over a slope. The influence of the vertical structure of turbulence under a breaking wave is analyzed by means of four different vertical profiles of eddy viscosity; the differences in terms of hydrodynamic features are also discussed. Among the four selected profiles, two of them ( the uniform one and that with uniform eddy viscosity over the top half of the water column which linearly decreases to zero over the lower half) give better overall performances when compared with experimental data concerning velocity profiles

On the hydrodynamics of breaking waves

none5R. BRIGANTI; R.E. MUSUMECI; G. BELLOTTI; M. BROCCHINI; E. FOTIR., Briganti; R. E., Musumeci; G., Bellotti; Brocchini, Maurizio; E., Fot