Shear viscosity behavior of highly concentrated suspensions at low and high shear-rates |
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Authors: | T Dabak O Yucel |
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Institution: | (1) Civil Engineering Department and Virginia Center for Coal and Energy Research, Virginia Polytechnic Institute and State University, 617 North Main Street, 24061 Blacksburg, Virginia, USA |
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Abstract: | A method is proposed for determining the shear viscosity behavior of highly concentrated suspensions at low and high shear-rates through the use of a formulation that is a function of three parameters signifying the effects of particle size distribution. These parameters are the intrinsic viscosity ], a parametern that reflects the level of particle association at the initiation of motion and the maximum packing concentration
m. The formulation reduces to the modified Eilers equation withn = 2 for high shear rates. An analytical method was used for the calculation of maximum packing concentration which was subsequently correlated with the experimental values to account for the surface induced interaction of particles with the fluid. The calculated values of viscosities at low and high shear-rates were found to be in good agreement with various experimental data reported in literature. A brief discussion is also offered on the reliability of the methods of measuring the maximum packing concentration.
r = /0
relative viscosity of the suspension
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volumetric concentration of solids
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k
n
coefficient which characterizes a specific effect of particle interactions
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m
maximum packing concentration
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r,0
relative viscosity at low shear-rates
- ]
intrinsic viscosity
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n, n
parameter that reflects the level of particle interactions at low and high shear-rates, respectively
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r,
relative viscosity at high shear-rates
- (m)s, (m)i, (m)l
packing factors for small, intermediate and large diameter classes
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v
s, vi, vl
volume fractions of small, intermediate and large diameter classes, respectively
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si, sl
coefficient to be used in relating a smaller to an intermediate and larger particle group, respectively
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is, il
coefficient to be used in relating an intermediate to a smaller and larger particle group, respectively
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ls, li
coefficient to be used in relating a larger to a smaller and intermediate particle group, respectively
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m0
maximum packing concentration for binary mixtures
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m,e
measured maximum packing concentration
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m,c
calculated maximum packing concentration |
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Keywords: | Viscosity concentrated suspension particle size distribution maximum packing concentration |
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