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Viscosity effects on local scour around vertical structures in clear-water conditions

Viscosity effects on local scour around vertical structures in clear-water conditions
Viscosity effects on local scour around vertical structures in clear-water conditions

Local scour represents the erosion process that occurs at the base of hydraulic structures overlying sediment beds. Horseshoe vortices forming at the bed-structure junction are the main responsible for sediment removal and dictate erosion rates as well as the maximum erosion depth resulting from a significant flow event. In steady-flow conditions this is often referred to as the equilibrium scour depth, which, for many hydraulic structures, represents a key parameter for foundation-design and risk-assessment purposes. The equilibrium scour depth has been investigated for decades and many predictive formulae have been developed following the classical empirical approach, whereby numerous experimental datasets are used to isolate and identify the influence of non-dimensional groups emerging from dimensional analysis. Within this context, the influence of obstacle Reynolds numbers, and consequently of viscous forces, has always been neglected because of the large Re values normally encountered in engineering and laboratory conditions. The present paper demonstrates that this assumption is largely incorrect especially for beds made of sand or finer material. The theoretical analysis presented in Manes and Brocchini ([1]) is herein extended to include viscosity effects and investigate their importance on equilibrium scour depths forming around obstacles resembling bridge piers.

2100-014X
1-7
Manes, Costantino
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Coscarella, Francesco
dbca9748-7ea6-498f-af4e-6fc5d6d05065
Rogers, Ashley
6e553b58-3613-4a1b-96ea-a5ec2b54ad2a
Gaudio, Roberto
b4931d9d-11af-46d4-9db7-2377a2622b2c
Manes, Costantino
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Coscarella, Francesco
dbca9748-7ea6-498f-af4e-6fc5d6d05065
Rogers, Ashley
6e553b58-3613-4a1b-96ea-a5ec2b54ad2a
Gaudio, Roberto
b4931d9d-11af-46d4-9db7-2377a2622b2c

Manes, Costantino, Coscarella, Francesco, Rogers, Ashley and Gaudio, Roberto (2018) Viscosity effects on local scour around vertical structures in clear-water conditions. E3S Web of Conferences, 40, 1-7, [03038]. (doi:10.1051/e3sconf/20184003038).

Record type: Article

Abstract

Local scour represents the erosion process that occurs at the base of hydraulic structures overlying sediment beds. Horseshoe vortices forming at the bed-structure junction are the main responsible for sediment removal and dictate erosion rates as well as the maximum erosion depth resulting from a significant flow event. In steady-flow conditions this is often referred to as the equilibrium scour depth, which, for many hydraulic structures, represents a key parameter for foundation-design and risk-assessment purposes. The equilibrium scour depth has been investigated for decades and many predictive formulae have been developed following the classical empirical approach, whereby numerous experimental datasets are used to isolate and identify the influence of non-dimensional groups emerging from dimensional analysis. Within this context, the influence of obstacle Reynolds numbers, and consequently of viscous forces, has always been neglected because of the large Re values normally encountered in engineering and laboratory conditions. The present paper demonstrates that this assumption is largely incorrect especially for beds made of sand or finer material. The theoretical analysis presented in Manes and Brocchini ([1]) is herein extended to include viscosity effects and investigate their importance on equilibrium scour depths forming around obstacles resembling bridge piers.

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More information

Accepted/In Press date: 1 January 2018
e-pub ahead of print date: 5 September 2018

Identifiers

Local EPrints ID: 425068
URI: http://eprints.soton.ac.uk/id/eprint/425068
ISSN: 2100-014X
PURE UUID: 79e2a5b2-f079-423b-8343-8b036bef38ed

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Date deposited: 10 Oct 2018 16:30
Last modified: 07 Oct 2020 00:43

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Contributors

Author: Costantino Manes
Author: Francesco Coscarella
Author: Ashley Rogers
Author: Roberto Gaudio

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