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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : An experimental study on viscous resuspension
An experimental study on viscous resuspension
Resuspension of an initially settled layer of particles has been observed not only under the action of shear by a turbulent
flow, but also by the action of a laminar shear flow. The paper reports the results and analysis of a set of experiments
performed in a fully developed laminar Hagen-Poiseuille channel flow of clear fluid over an initially settled layer of solid
particles, both monodisperse and slightly bidisperse (dmax/dmin=1.4) mixtures. A total of 30 experiments were carried out,
for particle volume fraction 􀟶􀯦 between 0.05 and 0.3 and flows with a mean velocity between 1.2 and 0.4 cm/s.
Resuspension heights of the particles forming the bed were recorded and compared with the ones obtained by previously
developed theoretical models by Leighton & Acrivos (1986) and Shauly et al. (2000) related to hydrodynamic segregation.
It was found that the model proposed by Leighton & Acrivos had an acceptable agreement with the experimental results,
even though it doesn¡¯t have any adjustable parameter. On the other hand the model proposed by Shauly et al., despite
didn¡¯t show an initial good fit with the data. Shauly et al.¡¯s model contains an adjustable parameter 􀜭, which is a
dimensionless empirical coefficient. By means of dimensional analysis, a relationship was found for 􀜭, as a function of the
solids volume fraction 􀟶􀯦 and a modified Shields number 􀟖, which is a measure of the relative importance of viscous
forces to those of gravity. Considering a modified parameter 􀜭, now depending on the flow and volume concentration, the
theoretical model by Shauly et al. showed a good agreement with the experimental data, better than that of Leighton and
Acrivos (1986). The results of the experiments with bidisperse suspensions were also compared with those theoretical
models considering a monodisperse layer but adjusting the maximum particle volume concentration 􀟶􀬴 with the models
proposed by Shauly et al. (1998) and Gondret & Petit (1997), obtaining a good agreement between measured and
computed data. The theoretical velocity profiles that were obtained with simplified numerical solutions of the previous
models had a good agreement with the ones measured by Schaflinger et al. (1995) for a similar geometry.
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Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 28/08/2015
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