Roles of particle-wall and particle-particle interactions in highly confined suspensions of spherical particles being sheared at low Reynolds numbers

Sangani, Ashok S.; Acrivos, Andreas; Peyla, Philippe

doi:10.1063/1.3613972

Cited by 32 publications

(34 citation statements)

References 27 publications

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“…The generality of this behavior for other suspensions is still unclear. A similar impact of confinement on ½η for small ϕ was reported for a confined rigid sphere suspension [62][63][64], but neither …”

Section: Prl 112 238304 (2014) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 59%

Prediction of Anomalous Blood Viscosity in Confined Shear Flow

et al. 2014

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Red blood cells play a major role in body metabolism by supplying oxygen from the microvasculature to different organs and tissues. Understanding blood flow properties in microcirculation is an essential step towards elucidating fundamental and practical issues. Numerical simulations of a blood model under a confined linear shear flow reveal that confinement markedly modifies the properties of blood flow. A nontrivial spatiotemporal organization of blood elements is shown to trigger hitherto unrevealed flow properties regarding the viscosity η, namely ample oscillations of its normalized value ½η ¼ ðη − η 0 Þ=ðη 0 ϕÞ as a function of hematocrit ϕ (η 0 ¼ solvent viscosity). A scaling law for the viscosity as a function of hematocrit and confinement is proposed. This finding can contribute to the conception of new strategies to efficiently detect blood disorders, via in vitro diagnosis based on confined blood rheology. It also constitutes a contribution for a fundamental understanding of rheology of confined complex fluids. Introduction.-Blood flow in microcirculation is essential for delivery of nutrients and removal of metabolic waste products to or from tissues. These functions are ensured by proper regulation of blood flow down to the capillary level. One of the main factors controlling capillary circulation is microvascular resistance to blood flow. This effect, in spite of extensive investigation, is still to be fully elucidated, and some fundamental issues remain open. Blood is to good approximation a suspension of red blood cells (RBCs). Blood rheology is dictated by dynamics of RBCs and their interaction with blood vessel walls. A significant research effort has been devoted so far to macroscopic rheology [1,2]. Most of the research on rheology in confined geometries has focused on the famous Fahraeus-Lindqvist (FL) effect [3][4][5] (see recent review [6]), where confinement has been shown to strongly affect the rheology, with a decrease in apparent viscosity as the diameter of a vessel decreases. These advances have not exhausted yet the intricate behavior inherent to rheology of confined blood, as reported in this Letter.A property that is commonly of interest for nonconfined suspensions is the viscosity as a function of the volume fraction ϕ, ηðϕÞ. In the dilute regime, i.e., when hydrodynamic interactions between suspended entities can be neglected, η takes the generic form η ¼ η 0 ð1 þ a 1 ϕÞ, where η 0 is the viscosity of the suspending fluid and a 1 is a quantity (the so-called intrinsic viscosity), that depends, in general, on the properties of the suspension. For example, for rigid particles, a 1 is just a universal number and is equal to 5=2; this is the famous Einstein result [7,8]. a 1 was calculated by Taylor [9] for emulsions, and extended to vesicle suspensions (a blood model) quite recently [10]. When the volume fraction increases, hydrodynamic interactions among suspended

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Section: Prl 112 238304 (2014) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 59%

Prediction of Anomalous Blood Viscosity in Confined Shear Flow

et al. 2014

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“…Although confining walls were considered in the above-mentioned studies their effect on the dynamics was not studied. We believe that it is of interest to study the impact of the walls on the dynamics of vesicles, a question that, to the best of our knowledge, has not been treated in the literature so far for vesicles, capsules, or red blood cells but only for a droplet [17] and a hard sphere [18].…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional vesicle dynamics under shear flow: Effect of confinement

2011

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Dynamics of a single vesicle under shear flow between two parallel plates is studied in two-dimensions using lattice-Boltzmann simulations. We first present how we adapted the lattice-Boltzmann method to simulate vesicle dynamics, using an approach known from the immersed boundary method. The fluid flow is computed on an Eulerian regular fixed mesh while the location of the vesicle membrane is tracked by a Lagrangian moving mesh. As benchmarking tests, the known vesicle equilibrium shapes in a fluid at rest are found and the dynamical behavior of a vesicle under simple shear flow is being reproduced. Further, we focus on investigating the effect of the confinement on the dynamics, a question that has received little attention so far. In particular, we study how the vesicle steady inclination angle in the tank-treading regime depends on the degree of confinement. The influence of the confinement on the effective viscosity of the composite fluid is also analyzed. At a given reduced volume (the swelling degree) of a vesicle we find that both the inclination angle, and the membrane tank-treading velocity decrease with increasing confinement. At sufficiently large degree of confinement the tank-treading velocity exhibits a nonmonotonous dependence on the reduced volume and the effective viscosity shows a nonlinear behavior.

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“…By substituting expression (29) in Eq. (10c), integrating in Y , and using boundary conditions (28a) and (28b), V Y (X,Y ) and the following differential equation for P(X) are obtained:…”

Section: B Motion Perpendicular To a Wall Or The Surface Of Another mentioning

confidence: 99%

“…These techniques, providing approximate analytical solutions, have also been employed to investigate the dynamics of a sphere/cylinder in shear flow confined between two parallel walls. [27][28][29] Due to the linearity of the Stokes equations, there is a linear relation between, on the one hand, the force, torque, and stresslet on a particle and, on the other hand, its linear and angular velocities as well as the velocity gradient of the ambient flow. 30 The set of linear relations between these parameters is defined by means of either the resistance or the mobility matrix.…”

Section: Introductionmentioning

confidence: 99%

Lubrication analysis of interacting rigid cylindrical particles in confined shear flow

Cardinaels

Stone

2015

Physics of Fluids

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Lubrication analysis is used to determine analytical expressions for the elements of the resistance matrix describing the interaction of two rigid cylindrical particles in two-dimensional shear flow in a symmetrically confined channel geometry. The developed model is valid for non-Brownian particles in a low-Reynolds-number flow between two sliding plates with thin gaps between the two particles and also between the particles and the walls. Using this analytical model, a comprehensive overview of the dynamics of interacting cylindrical particles in shear flow is presented. With only hydrodynamic interactions, rigid particles undergo a reversible interaction with no cross-streamline migration, irrespective of the confinement value. However, the interaction time of the particle pair substantially increases with confinement, and at the same time, the minimum distance between the particle surfaces during the interaction substantially decreases with confinement. By combining our purely hydrodynamic model with a simple on/off non-hydrodynamic attractive particle interaction force, the effects of confinement on particle aggregation are qualitatively mapped out in an aggregation diagram. The latter shows that the range of initial relative particle positions for which aggregation occurs is increased substantially due to geometrical confinement. The interacting particle pair exhibits tangential and normal lubrication forces on the sliding plates, which will contribute to the rheology of confined suspensions in shear flow. Due to the combined effects of the confining walls and the particle interaction, the particle velocities and resulting forces both tangential and perpendicular to the walls exhibit a non-monotonic evolution as a function of the orientation angle of the particle pair. However, by incorporating appropriate scalings of the forces, velocities, and doublet orientation angle with the minimum free fraction of the gap height and the plate speed, master curves for the forces versus orientation angle can be constructed.

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Roles of particle-wall and particle-particle interactions in highly confined suspensions of spherical particles being sheared at low Reynolds numbers

Cited by 32 publications

References 27 publications

Prediction of Anomalous Blood Viscosity in Confined Shear Flow

Prediction of Anomalous Blood Viscosity in Confined Shear Flow

Two-dimensional vesicle dynamics under shear flow: Effect of confinement

Lubrication analysis of interacting rigid cylindrical particles in confined shear flow

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