Experimental flows through an array of emerged or slightly submerged square cylinders over a rough bed

Marina Oukacine,Frédérique Larrarte,Sébastien Proust,Nicole Goutal

doi:10.1038/s41597-020-00791-w

Abstract

The experimental dataset presented was collected in an 18 m long and 1 m wide laboratory flume. Low to high flood flows through an urbanized floodplain were modelled. The floodplain bed is rough, modelled with dense artificial grass. A square cylinder array, representing house models, was set on the rough bed. The cylinder immersion rate was varied: cylinders are emerged for three flow cases and slightly submerged for one case. The experimental dataset comprises water levels, measured using an ultrasonic transit time probe, velocities across the channel measured using an Acoustic Doppler Velocimetry with a side looking probe, and velocities in longitudinal-vertical planes measured using Particle Image Velocimetry. These data could help understanding the physical processes associated with high flood flows through urbanized floodplains, with a focus on the transition from emerged to submerged obstacles. They could also be used as benchmark data to assess the ability of numerical models from one to three-dimensions to estimate the flood hazard (water depth, velocity) over a wide range of flood event magnitudes.

Highlights

Background & SummaryAs a result of climate change, extreme floods will become more frequent and more intense
This study aimed at investigating if there is a change in the physical processes when the houses initially emerged become weakly submerged and at providing well documented data for validation of simulations
Very few experimental studies have focused on this issue by considering a dense urban area, as depicted in Fig. 1a 2

Summary

Introduction

As a result of climate change, extreme floods will become more frequent and more intense. People and properties, such as housing and industrial facilities, must be protected against these floods for which data are very scarce or even non-existent[1]. This study aimed at investigating if there is a change in the physical processes when the houses initially emerged become weakly submerged and at providing well documented data for validation of simulations. Most of them provide only water level measurements and are not interested in the study of the vertical confinement. Another complementary area of research concerns the development of simulation tools for extreme flows in a congested area. More information can be found in a review of the data available[19]

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Methods