Particle stress and viscous compaction during shear of dense suspensions

Prasad, D. H. L.; Kytomaa, Harri

doi:10.1016/0301-9322(95)00018-s

Cited by 47 publications

(52 citation statements)

References 22 publications

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“…In Figure 8, comparison is made with the data of Hanes and Inman, 10 Prasad and Kytomaa, 9 and the empirical formula of Zarraga et al 25 The effective viscosities from Hanes et al and Prasad FIG. 7.…”

Section: -9mentioning

confidence: 99%

“…5,6 Fewer suspension studies have been conducted with grain sizes larger than a millimeter and at Reynolds numbers greater than one. [7][8][9][10] In these high Reynolds number flows, the inertia of one or both phases is important and collisions between the particles may occur; the flow may also transition to turbulence. The first experimental study exploring the transition to an inertial suspension flow was conducted by Bagnold 7,11 who made rheometric measurements using a small concentric cylinder device with an outer rotating wall.…”

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Rheological measurements of large particles in high shear rate flows

et al. 2012

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How to impose stick boundary conditions in coarse-grained hydrodynamics of Brownian colloids and semiflexible fiber rheology J. Chem. Phys. 136, 064901 (2012) This paper presents experimental measurements of the rheological behavior of liquid-solid mixtures at moderate Stokes and Reynolds numbers. The experiments were performed in a coaxial rheometer that was designed to minimize the effects of secondary flows. By changing the shear rate, particle size, and liquid viscosity, the Reynolds numbers based on shear rate and particle diameter ranged from 20 to 800 (Stokes numbers from 3 to 90), which is higher than examined in earlier rheometric studies. Prior studies have suggested that as the shear rate is increased, particleparticle collisions also increase resulting in a shear stress that depends non-linearly on the shear rate. However, over the range of conditions that were examined in this study, the shear stress showed a linear dependence on the shear rate. Hence, the effective relative viscosity is independent of the Reynolds and Stokes numbers and a nonlinear function of the solid fraction. The present work also includes a series of roughwall experiments that show the relative effective viscosity is also independent of the shear rate and larger than in the smooth wall experiments. In addition, measurements were made of the near-wall particle velocities, which demonstrate the presence of slip at the wall for the smooth-walled experiments. The depletion layer thickness, a region next to the walls where the solid fraction decreases, was calculated based on these measurements. The relative effective viscosities in the current work are larger than found in low-Reynolds number suspension studies but are comparable with a few granular suspension studies from which the relative effective viscosities can be inferred.

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Rheological measurements of large particles in high shear rate flows

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“…This gives rise to a number of effects present in dry granular materials such as dilatancy, 4, 5 shear banding, 6 particle jamming, 7,8 and frictional behavior. 9,10 At the same time, the grains are saturated with viscous fluids and inherit some of the features of concentrated suspensions such as shear thickening, particle migration, and normal stress effects. 11,12 Since granular suspensions exhibit properties typical of both granular materials and viscous non-Newtonian fluids, it is natural to wonder whether these distinctive properties are present at the same time or whether, on the contrary, they are mutually exclusive, i.e., they are intrinsic to either viscous or frictional regimes.…”

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confidence: 99%

Granular suspension avalanches. I. Macro-viscous behavior

2013

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We experimentally studied the flow behavior of a fixed volume of granular suspension, initially contained in a reservoir and released down an inclined flume. Here "granular suspension" refers to a suspension of non-Brownian particles in a viscous fluid. Depending on the solids fraction, density mismatch, and particle size distribution, a wealth of behaviors can be observed. Here we report and interpret results obtained with granular suspensions, which consisted of neutrally buoyant particles with a solids fraction (φ = 0.575-0.595) close to the maximum random packing fraction (estimated at φ m = 0.625). The particles had the same refractive index as the fluid, which made it possible to measure the velocity profiles inside the moving bulk and far from the sidewalls. Additional information such as the front position and the flow depth was also recorded. Three regimes were observed. At early times, the flow features were reminiscent of homogeneous Newtonian fluids (e.g., the same dependence of the front position on time). At later times, the free surface became more and more bumpy as fractures developed within the bulk. This fracture process ultimately gave rise to a stick-slip regime, in which the suspension moved intermittently. In this paper, we focus on the first regime referred to as the macroviscous regime. Although the bulk flow properties looked like those of Newtonian fluids, the internal dynamics were much richer. C 2013 American Institute of Physics.

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“…In some of these papers, there is only a passing reference to Bagnold's work. However, several papers have tried to repeat or to simulate the experimental results, and the constitutive relations have been applied to a range of fluid-solid flows (for example Savage & Jeffrey 1981;Savage & McKeown 1983;Hanes & Inman 1985;Shibata & Mei 1986;Prasad & Kytömaa 1995;Hutter & Rajagopal 1994;Potapov, Hunt & Campbell 2001). Although the research has had tremendous impact on the fields of granular materials, debris flows, slurry and sediment transport, there has not been a critical analysis of the experiments.…”

Section: Introductionmentioning

confidence: 99%

Revisiting the 1954 suspension experiments of R. A. Bagnold

et al. 2002

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In 1954 R. A. Bagnold published his seminal findings on the rheological properties of a liquid-solid suspension. Although this work has been cited extensively over the last fifty years, there has not been a critical review of the experiments. The purpose of this study is to examine the work and to suggest an alternative reason for the experimental findings. The concentric cylinder rheometer was designed to measure simultaneously the shear and normal forces for a wide range of solid concentrations, fluid viscosities and shear rates. As presented by Bagnold, the analysis and experiments demonstrated that the shear and normal forces depended linearly on the shear rate in the 'macroviscous' regime; as the grain-to-grain interactions increased in the 'grain-inertia' regime, the stresses depended on the square of the shear rate and were independent of the fluid viscosity. These results, however, appear to be dictated by the design of the experimental facility. In Bagnold's experiments, the height (h) of the rheometer was relatively short compared to the spacing (t) between the rotating outer and stationary inner cylinder (h/t = 4.6). Since the top and bottom end plates rotated with the outer cylinder, the flow contained two axisymmetric counter-rotating cells in which flow moved outward along the end plates and inward through the central region of the annulus. At higher Reynolds numbers, these cells contributed significantly to the measured torque, as demonstrated by comparing Bagnold's pure-fluid measurements with studies on laminar-to-turbulent transitions that pre-date the 1954 study. By accounting for the torque along the end walls, Bagnold's shear stress measurements can be estimated by modelling the liquid-solid mixture as a Newtonian fluid with a corrected viscosity that depends on the solids concentration. An analysis of the normal stress measurements was problematic because the gross measurements were not reported and could not be obtained.

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Particle stress and viscous compaction during shear of dense suspensions

Cited by 47 publications

References 22 publications

Rheological measurements of large particles in high shear rate flows

Rheological measurements of large particles in high shear rate flows

Granular suspension avalanches. I. Macro-viscous behavior

Revisiting the 1954 suspension experiments of R. A. Bagnold

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