HYDRODYNAMICS UNDER LARGE-SCALE REGULAR AND BICHROMATIC BREAKING WAVES

Dominic Van Der A,Guillaume Fromant,Stefan Carstensen,Ivã¡N Cã¡Ceres,Stuart Mclelland,Carla Faraci,Joep Van Der Zanden,David Hurther,Simon Clark,Gerben Ruessink,Pietro Scandura,James Cooper,Ming Li,David Fuhrman,Carmelo Petrotta,Joost Brinkkemper,Bjarke Eltard-Larsen

doi:10.9753/icce.v36.waves.90

Abstract

Multiphase CFD models recently have proved promising in modelling crossâ€shore sediment transport and morphodynamics (Jacobsen et al 2014). However, modelling breaking wave turbulence remains a major challenge for these models, because it occurs at very different spatial and temporal length scales and involves the interaction between surface generated turbulence and turbulence generated in the bottom boundary layer. To an extent these challenges arise from a lack of appropriate experimental data, since most previous experimental studies involved breaking waves at small-scale, and have not permitted investigation of the turbulent boundary layer processes. Moreover, most existing studies have concentrated on regular waves, thereby excluding the flow and turbulence dynamics occurring at wave group time-scales under irregular waves within the surf zone. These limitations motivated a new experiment in the large-scale CIEM wave flume in Barcelona involving regular and irregular waves. The experiment was conducted in May-July 2017 within the HYDRALAB+ Transnational Access project HYBRID.

Highlights

The instruments deployed from a mobile measurement frame included two acoustic velocity profilers (ADVP) for wave bottom boundary layer velocities, two Laser Doppler Anemometers (LDA), two acoustic Doppler velocimeters (ADV), and two electromagnetic flow meters (EMF) at elevations above the wave boundary layer
Velocity profiles from the bed up to still water level were measured at 22 cross-shore locations across the shoaling to inner surf zone, typically with a vertical resolution of 1.5mm in the wave boundary layer and 10 cm at higher levels
Figure 1 shows a preliminary result of the time-averaged cross-shore velocity under the bichromatic wave condition

Summary

Introduction

EXPERIMENTS The bed consisted of a concrete barred profile generated in a previous experiment of van der A et al (2017). For the present experiment a layer of gravel (D50 = 9 mm) was glued to the concrete surface to increase and homogenize the bed roughness.

Results

Conclusion