Shear‐Induced Structure in a Concentrated Suspension of Solid Spheres

Gadala-Maria, Francis; Acrivos, Andreas

doi:10.1122/1.549584

Cited by 486 publications

(249 citation statements)

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“…Gadala-Maria and Acrivos (18) found nonlinear response curves during oscillatory experiments on suspensions of polystyrene spheres in silicon oil. According to them an explanation of their findings is that, upon being sheared, the suspensions develop a structure which renders them anisotropic fluids.…”

Section: -9797/92 $300mentioning

confidence: 99%

Viscoelastic properties of concentrated shear-thickening dispersions

Boersma

Lavèn

Stein

1992

Journal of Colloid and Interface Science

119

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The viscoelastic properties of electrostatically stabilized concentrated dispersions of silica and of glass particles in a glycerol/water mixture are studied by oscillatory shear measurements. These dispersions are shear-thickening in steady shear flow. At most frequencies the loss modulus is found to dominate the storage modulus. At certain critical combinations of deformation amplitude and frequency the response signal becomes distorted, containing higher harmonics. This phenomenon can be ascribed to flow blockage, closely related to shear thickening in steady shear flow. When plotting the critical deformation against the frequency, three different regions can be detected. At low frequencies there is the steady shear flow limit, at intermediate frequencies double-layer overlap causes nonlinearity in the response signal, and at high frequencies there is a region where the critical deformation for flow blockage is a system-dependent function of the frequency, but is independent of the volume fraction. The magnitudes of the storage moduli are found to be in reasonable agreement with theoretical predictions.

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Section: -9797/92 $300mentioning

confidence: 99%

Viscoelastic properties of concentrated shear-thickening dispersions

Boersma

Lavèn

Stein

1992

Journal of Colloid and Interface Science

119

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“…monodisperse, non-Brownian spheres undergoing linear shear flow, no measurements of how the velocity fluctuations are affected by the suspension microstructure appear to have been conducted thus far. Recall that the experimental work of Gadala-Maria & Acrivos (1980) provided, for the first time, clear evidence that concentrated suspensions of monodisperse, non-Brownian spheres develop an anisotropic structure when sheared. They showed that, when the direction of shear was reversed, the shear stress measured in a parallel plate device underwent a transient response not present when the shearing was started again in the same direction, and thereby concluded that the underlying structure was not only anisotropic but asymmetric under reversal of the flow direction, i.e.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and velocity fluctuations in sheared suspensions

et al. 2004

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The velocity fluctuations present in macroscopically homogeneous suspensions of neutrally buoyant, non-Brownian spheres undergoing simple shear flow, and their dependence on the microstructure developed by the suspensions, are investigated in the limit of vanishingly small Reynolds numbers using Stokesian dynamics simulations. We show that, in the dilute limit, the standard deviation of the velocity fluctuations (the so-called suspension temperature) is proportional to the volume fraction, in both the transverse and the flow directions, and that a theoretical prediction, which considers only for the hydrodynamic interactions between isolated pairs of spheres, is in good agreement with the numerical results at low concentrations. Furthermore, we show that the whole velocity autocorrelation function can be predicted, in the dilute limit, based purely in two-particle encounters. We also simulate the velocity fluctuations that would result from a random hard-sphere distribution of spheres in simple shear flow, and thereby investigate the effects of the microstructure on the velocity fluctuations. Analogous results are discussed for the fluctuations in the angular velocity of the suspended spheres. In addition, we present the probability density functions for all the linear and angular velocity compo- The simulations include a non-hydrodynamic repulsive force between the spheres which, although extremely short ranged, leads to the development of fore-aft asymmetric distributions for large enough volume fractions, if the range of that force is kept unchanged.On the other hand, we show that, although the pair distribution function recovers its fore-aft symmetry in dilute suspensions, it remains anisotropic and that this anisotropy can be accurately described by assuming the complete absence of any permanent doublets of spheres.We also present a simple correction to the analysis of laser-Doppler velocimetry measurements, that only takes into account the mean angular rotation of the spheres in the vorticity direction, and which substantially improves the interpretation of these measurements at low volume fractions.

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“…Blood shows remarkable non-Newtonian effects primarily caused by RBC -RBC interactions and RBC -protein interactions: the aggregation and disaggregation of RBCs and their deformation dictate the value of viscosity [1,2]. A wide body of experimental evidence shows that flowing suspensions of rigid and deformable particles exhibit particle migration [3][4][5][6][7][8][9][10] with a general trend showing migration from regions of higher shear rate to regions of lower shear rate. RBCs also show this behaviour and their migration to the centre of micro and small vessels (micrometre to millimetre size) and the consequent segregation of PLTs near the wall has been the subject of intense study in the past years, both numerically [11][12][13][14] and experimentally [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport

Biasetti

Spazzini

Hedin

et al. 2014

J. R. Soc. Interface.

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Shear-induced migration of red blood cells (RBCs) is a well-known phenomenon characterizing blood flow in the small vessels (micrometre to millimetre size) of the cardiovascular system. In large vessels, like the abdominal aorta and the carotid artery (millimetre to centimetre size), the extent of this migration and its interaction with secondary flows has not been fully elucidated. RBC migration exerts its influence primarily on platelet concentration, oxygen transport and oxygen availability at the luminal surface, which could influence vessel wall disease processes in and adjacent to the intima. Phillips' shear-induced particle migration model, coupled to the Quemada viscosity model, was employed to simulate the macroscopic behaviour of RBCs in four patient-specific geometries: a normal abdominal aorta, an abdominal aortic aneurysm (AAA), a normal carotid bifurcation and a stenotic carotid bifurcation. Simulations show a migration of RBCs from the near-wall region with a lowering of wall haematocrit (volume fraction of RBCs) on the posterior side of the normal aorta and on the lateralexternal side of the iliac arteries. A marked migration is observed on the outer wall of the carotid sinus, along the common carotid artery and in the carotid stenosis. No significant migration is observed in the AAA. The spatial and temporal patterns of wall haematocrit are correlated with the near-wall shear layer and with the secondary flows induced by the vessel curvature. In particular, secondary flows accentuate the initial lowering in RBC near-wall concentration by convecting RBCs from the inner curvature side to the outer curvature side. The results reinforce data in literature showing a decrease in oxygen partial pressure on the inner curvature wall of the carotid sinus induced by the presence of secondary flows. The lowering of wall haematocrit is postulated to induce a decrease in oxygen availability at the luminal surface through a diminished concentration of oxyhaemoglobin, hence contributing, with the reported lowered oxygen partial pressure, to local hypoxia.

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Shear‐Induced Structure in a Concentrated Suspension of Solid Spheres

Cited by 486 publications

References 0 publications

Viscoelastic properties of concentrated shear-thickening dispersions

Viscoelastic properties of concentrated shear-thickening dispersions

Microstructure and velocity fluctuations in sheared suspensions

Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport

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