In the last decades, important efforts have been made to better understand the effects of surface roughness on the mean flow. These studies have been performed investigating turbulent channel flows, turbulent boundary layers or pipe flows. The most evident effect of the roughness is the increase of the overall resistance, corresponding to a decrease of the mean streamwise velocity profile in the logarithmic region. This reduction is known as roughness function ΔU+ (the symbol “+” represents quantities made non dimensional using the friction velocity u*, or the viscous length scale ν/u*). In the present study, ES is correlated with the roughness function ΔU+, so that it can be considered a geometric parameter able to predict the mean flow reduction. The current study is aimed at finding a law able to predict the roughness function produced by regular or irregular roughness, using LES techniques.

ESTIMATION OF THE ROUGHNESS FUNCTION: TOWARD A UNIVERSAL LAW

Mauro De Marchis
;
Barbara Milici;
2018

Abstract

In the last decades, important efforts have been made to better understand the effects of surface roughness on the mean flow. These studies have been performed investigating turbulent channel flows, turbulent boundary layers or pipe flows. The most evident effect of the roughness is the increase of the overall resistance, corresponding to a decrease of the mean streamwise velocity profile in the logarithmic region. This reduction is known as roughness function ΔU+ (the symbol “+” represents quantities made non dimensional using the friction velocity u*, or the viscous length scale ν/u*). In the present study, ES is correlated with the roughness function ΔU+, so that it can be considered a geometric parameter able to predict the mean flow reduction. The current study is aimed at finding a law able to predict the roughness function produced by regular or irregular roughness, using LES techniques.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11387/133582
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