Additifs réducteurs de perte de charge en écoulement

Herzhaft, Benjamin

doi:10.2516/ogst:2000037

Cited by 4 publications

(1 citation statement)

References 16 publications

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“…The drag reduction effect allows for dramatic reductions in wall friction and thus linear head losses of up to 80% [6][7]. The origin of this phenomenon lies in the turbulent structures of the flow and the polymer macromolecules added to the fluid [8].…”

Section: Introductionmentioning

confidence: 99%

Strengthen resilience to rivers flooding by the drag reduction technique

Bouchenafa¹,

Dang-Vu²,

Dang-Vu

2022

IOP Conf. Ser.: Earth Environ. Sci.

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Urban agglomerations face the risk of overflowing rivers due to intense urbanization in flood-prone areas and the climate change effects. Despite the important protective measures deployed to reduce the fluvial flooding risk, additional efforts are still needed. This work aims to propose a new complementary non-structural protection measure, used to reduce the river flooding risk. The study is part of the NABRAPOL (NEBRASKA POLYMER) project, which aims to improve knowledge of the drag reduction effect by adding polymers in open-channel flows. The addition of polymers, even in limited concentrations, allows high friction to decrease with the typical Manning coefficient reduced up to 45%. An application case on a real watercourse is presented in this article. Two measurement campaigns are carried out on a river along 30 km. Experimental devices are deployed, and non-intrusive hydraulic measuring instruments are installed at the study field. Surface velocities are evaluated by the Large-Scale Particle Image Velocimetry (LSPIV) technique, and water depth is measured using ultrasonic radar sensors over the river. Measurement results show that the addition of 20 ppm of polymers in the flows results in a marked drag reduction by decreasing the water depth to 18% of its initial depth. The drag reduction technique by addition of small concentrations of polymers can be considered as a new and effective method to reinforce the measures already deployed in the flood risk management strategy since it allows the water depth to be decreased thus avoid overflowing rivers in the extreme flooding event.

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Section: Introductionmentioning

confidence: 99%

Strengthen resilience to rivers flooding by the drag reduction technique

Bouchenafa¹,

Dang-Vu²,

Dang-Vu

2022

IOP Conf. Ser.: Earth Environ. Sci.

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Effect of polymer additives on dynamics of water level in an open channel

Kumar,

Graham

2023

Journal of Non-Newtonian Fluid Mechanics

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Smoother Than Smooth: Increasing the Flow Conveyance of an Open-Channel Flow by Using Drag Reduction Methods

et al. 2019

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The drag reduction method by polymer additives is a common strategy used to minimize friction losses when carrying fluids (water, oil, slurries) in pipes over long distances. Previous studies showed that the interactions between the polymer and the turbulent structures of the flow tend to modify the streamwise velocity profile close to the walls by adding a so-called elastic sublayer between the classical viscous and log layers. The gain in linear head losses can reach up to 80%, depending on the roughness of the walls and the concentration of polymers. The application of this technique to sewers and the subsequent gain in discharge capacity motivated this work to quantitatively measure the drag reduction in classical open-channel flows. Three measurement campaigns were performed in a dedicated long flume for several water discharges and several polymer concentrations: backwater curves over smooth and rough channel walls (including velocity and turbulent shear stress profiles) and flows around emerging obstacles. The addition of polymers, even in limited concentrations, allowed a high friction decrease with a typical Darcy-Weisbach coefficient reduced by factors of 2 and 1.5, respectively in smooth and rough walls configurations without obstacles; but without strong modifications of the non-dimensional velocity profiles. Oppositely, when adding emerging obstacles,

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Additifs réducteurs de perte de charge en écoulement

Cited by 4 publications

References 16 publications

Strengthen resilience to rivers flooding by the drag reduction technique

Strengthen resilience to rivers flooding by the drag reduction technique

Effect of polymer additives on dynamics of water level in an open channel

Smoother Than Smooth: Increasing the Flow Conveyance of an Open-Channel Flow by Using Drag Reduction Methods

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