Wave-Current Flow and Vorticity Close to a Fixed Rippled Bed

Alessia Ruggeri,Carla Faraci,Rosaria Ester Musumeci

doi:10.3390/jmse8110867

Alessia Ruggeri, Carla Faraci + Show 1 more

Open Access

https://doi.org/10.3390/jmse8110867

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Abstract

An experimental study of wave and current interaction over ripples is presented in this paper. The campaign was carried out at the shallow water tank at the Danish Hydraulic Institute (DHI, Denmark), in the framework of the TA WINGS (Waves plus currents INteracting at a right anGle over rough bedS), funded by the European Union (EU) through the Hydralab+ program. Mean velocity profiles, measured with acoustic Doppler velocimeters for different flow conditions including current only, wave only and wave plus current were recorded and allowed to recover flow and vorticity fields. Recirculating cells in both wave only and wave plus current conditions form but they flatten when the current superposes over the wave. It was found that the superposition of current reduces the undertow present in the case of only waves and leads to an increase of vorticity outside the boundary layer. Instead, inside the boundary layer, the vorticity is dumped by the effect of current.

Highlights

The interactions of waves and currents are complex hydrodynamic phenomena that strongly influence the flow near the coast
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This paper investigated the orthogonal wave current interaction over a rippled bed acquired in the framework of the WINGS campaign

Summary

Introduction

The interactions of waves and currents are complex hydrodynamic phenomena that strongly influence the flow near the coast. Faraci et al [2] carried out a numerical study over ripples with round crest for wave only case and orthogonal interaction of wave and current Near the bed, they found that vortices detach over the crests at phases 0–45◦ and when the current overlaps, the wave leads to a slight decrease of vorticity. In the second part (Section 3), the analysis of the mean velocity field, the study of flow field and vorticity are discussed comparing the wave only case (WO) with the wave and current case (WC) focusing attention on the boundary layer but taking into account the variations that occur moving away from the bed.

Experimental Set up and Procedure

Findings

Conclusions