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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water engineering : A numerical study on hydraulic resistance in rough bed flows
A numerical study on hydraulic resistance in rough bed flows
Author : RICHARD MCSHERRY(1), THORSTEN STOESSER(1) & ROGER FALCONER(1)
ABSTRACT
We investigate the contributions to total bed friction arising from viscous, turbulent and form-induced stresses,
secondary currents, non-uniformity, and unsteadiness in open channel flows. We employ highly-resolved Large Eddy
Simulations to simulate laminar and turbulent flow over rough and smooth beds to study the behaviour of the friction
factor in the five roughness regimes that were hypothesised by Nikora (2009). By applying the double averaging
methodology to our simulated flow fields we quantify the form-induced stress that is produced by the inclusion of
roughness elements, and show that this stress can be significantly non-zero even in laminar flows. We also ˇ°reconstructˇ±
the friction factor for turbulent smooth bed flows according to Nikora's theoretical expression, using the simulated
turbulent stresses, and find that the reconstructed value is in good agreement with the value obtained using the more
conventional relationship between streamwise pressure gradient and bed shear stress.
File Size : 693,169 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water engineering
Date Published : 19/08/2015
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