Shear-induced dispersion in a dilute suspension of rough spheres

Cunha, Francisco Ricardo; Hinch, E. J.

doi:10.1017/s0022112096001619

Cited by 242 publications

(266 citation statements)

References 9 publications

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“…Such surface asperities promote an early contact and impose the surface-to-surface separation between particles and the magnitude of lubrication stress consequently. Surface roughness can therefore significantly modify the rheological properties and the microstructure of suspensions, as confirmed by many numerical studies (Sierou & Brady 2002;Drazer et al 2002Drazer et al , 2004DaCunha & Hinch 1996). Theoretical studies in dilute regimes show that large roughness can decrease viscosity as well as increase |N 1 | and |N 2 | (Wilson 2005;Wilson & Davis 2002;Davis et al 2003;Zarraga & Leighton Jr 2001).…”

Section: Introductionmentioning

confidence: 75%

“…Due to the imposed shear flow, the spheres will hydrodynamically interact and possibly touch in the case of rough spheres. A theoretical reference solution is computed using the approach already presented in other works (DaCunha & Hinch 1996;Zarraga & Leighton Jr 2001;Metzger et al 2013). The relative trajectories are integrated in time using the theoretical resistance functions R 2B theo .…”

Section: A Pair Of Rough Frictional Spheres In a Shear Flowmentioning

confidence: 99%

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Rheology of sheared suspensions of rough frictional particles

et al. 2014

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This paper presents three-dimensional numerical simulations of non-Brownian concentrated suspensions in a Couette flow at zero Reynolds number using a fictitious domain method. Contacts between particles are modelled using a discrete element method (DEM)-like approach, which allows for a more physical description, including roughness and friction. This work emphasizes the effect of friction between particles and its role on rheological properties, especially on normal stress differences. Friction is shown to notably increase viscosity and second normal stress difference $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}|N_2|$ and decrease $|N_1|$, in better agreement with experiments. The hydrodynamic and contact contributions to the overall particle stress are particularly investigated. This shows that the effect of friction is mostly due to the additional contact stress since the hydrodynamic stress remains unaffected by friction. Simulation results are also compared with experiments, such as normal stresses or effective friction coefficient $\mu (I_v)$, and the agreement is improved when friction is accounted for. This suggests that friction is operative in actual suspensions.

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Section: Introductionmentioning

confidence: 75%

Section: A Pair Of Rough Frictional Spheres In a Shear Flowmentioning

confidence: 99%

Rheology of sheared suspensions of rough frictional particles

et al. 2014

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“…Da Cunha and Hinch [36] clearly demonstrated that shear induced self-diffusion is function of the strength of repulsive forces which yield a net displacement at each pairwise particle interaction. Particles are moving across streamlines enhancing cross-stream diffusion (adhesion to wall occurs sooner).…”

Section: Channel Permeabilitymentioning

confidence: 99%

Numerical investigation of channel blockage by flowing microparticles

2014

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a b s t r a c tThe dynamic formation of 3D structures of microparticle aggregates blocking the flow through straight microchannels is investigated by direct numerical simulation of the coupled motion of particles and fluid. We use the Force Coupling Method to handle simultaneously multibody hydrodynamic interactions of confined flowing suspension together with particle-particle and particle-wall surface interactions leading to adhesion and aggregation of particles. The basic idea of the Force Coupling Method relies on a multipole expansion of forcing terms (added to the Navier-Stokes equations) accounting for the velocity perturbation induced by the presence of particles in the fluid flow. When a particle reaches the wall or an attached particle, we consider that the adhesion is irreversible and this particle remains fixed. We investigate the kinetics of the microchannel blockage for several solid volumetric concentrations and different surface interaction forces. Many physical quantities such as the temporal evolution of the bulk permeability, capture efficiency, modification of the fluid flow and forces acting on attached particles are analyzed. We show that physical-chemical interactions, modeled by DLVO forces, are essential features which control the blockage dynamics and aggregate structure. IntroductionThe physics of transport, deposition, detachment and reentrainment of colloidal particles suspended in a fluid are of major interest in many areas of fluids engineering: fouling of heat exchangers, contamination of nuclear reactors, plugging of filtration membranes and occlusion of human veins, deposits in microelectronics and in the paper industry. In many solid/liquid separation processes such as micro-filtration or ultrafiltration of water, the limitation of the process performance is related to the fouling of filtration devices. To prevent or control the occurrence of fouling, it is necessary to achieve a better understanding of the respective roles of physical-chemical phenomena and hydrodynamic interactions in a confined suspension of particles. Non-hydrodynamic surface interactions and the adhesion of particles onto solid surfaces are the essential features to be modeled. However, mainly because of a complex interplay between the hydrodynamics of the flow, the physical-chemical properties of the filtered suspensions (often in a colloidal state) and the nature of the solid material, predicting fouling dynamics is still challenging.Different experimental techniques and numerical approaches have been developed to achieve new insights on the local structure of particle aggregates and the kinetics of blockage. Sharp and Adrian [4], by means of experiments in microtubes, observed blockage due to arch formation. The experiments were performed using liquids seeded with polystyrene beads at low volumetric concentration. They showed that a stable balance between the hydrodynamic forces and contact forces (mainly solid friction) between particles and the wall provokes the formation of arches. Wyss et al.[5] stu...

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“…where the mobility functions A and B are functions only of r. Here, we shall use the expressions for these functions given by da Cunha & Hinch (1996), who divided the interval r > 2 into three different regions (see da Cunha & Hinch (1996) for details on how they obtained the expressions for A and B in each region). Specifically: a) within the lubrication region 2 < r ≤ 2.01,…”

Section: Microscopic Structure Induced By the Shearmentioning

confidence: 99%

“…For two freely-moving spheres in a simple shear flow, the velocity fluctuation of a sphere induced by a second sphere the center of which is located at r is given by (da Cunha & Hinch 1996):…”

Section: Velocity Fluctuationsmentioning

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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Shear-induced dispersion in a dilute suspension of rough spheres

Cited by 242 publications

References 9 publications

Rheology of sheared suspensions of rough frictional particles

Rheology of sheared suspensions of rough frictional particles

Numerical investigation of channel blockage by flowing microparticles

Microstructure and velocity fluctuations in sheared suspensions

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