Simulation of binary dispersion system of droplets with size and surface tension difference under Couette flow

Makino, Masato; Sugihara‐Seki, Masako

doi:10.17106/jbr.28.7

Cited by 2 publications

(2 citation statements)

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“…Flow-induced segregation is ubiquitous in multicomponent suspensions and granular materials, including systems as disparate as hard macroscopic particles in air [1], polydisperse droplet suspensions [2], foams [3], and blood. During blood flow, the focus of the present work, both the leukocytes and platelets segregate near the vessel walls, a phenomenon known as margination, while the red blood cells (RBCs) tend to be depleted in the near-wall region, forming a so-called cell-free or depletion layer [4].…”

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Margination Regimes and Drainage Transition in Confined Multicomponent Suspensions

2015

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A mechanistic theory is developed to describe segregation in confined multicomponent suspensions such as blood. It incorporates the two key phenomena arising in these systems at low Reynolds number: hydrodynamic pair collisions and wall-induced migration. In simple shear flow, several regimes of segregation arise, depending on the value of a "margination parameter" M. Most importantly, there is a critical value of M below which a sharp "drainage transition" occurs: one component is completely depleted from the bulk flow to the vicinity of the walls. Direct simulations also exhibit this transition as the size or flexibility ratio of the components changes.Introduction. Flow-induced segregation is ubiquitous in multicomponent suspensions and granular materials, including systems as disparate as hard macroscopic particles in air [1], polydisperse droplet suspensions [2], foams [3], and blood. During blood flow, the focus of the present work, both the leukocytes and platelets segregate near the vessel walls, a phenomenon known as margination, while the red blood cells (RBCs) tend to be depleted in the near-wall region, forming a so-called cell-free or depletion layer [4]. Engineering the margination process has been proposed for microfluidic cell separations in blood (e.g. [5]) as well as for enhanced drug delivery to the vasculature [6].Direct simulations of flowing multicomponent suspensions -models of blood -can capture margination phenomena [7][8][9][10][11][12][13][14][15][16], but developing a fundamental understanding of underlying mechanisms and parameterdependence from simulations is difficult. It is thus important to have a simple yet mechanistic mathematical model, ideally one with closed form solutions that reveal parameter-dependence, that can distill out the essential phenomena that drive segregation and capture the key effects and transitions. We present such a model here.Theory. We consider a dilute suspension containing N s types of deformable particles with total volume fraction φ undergoing flow in a slit bounded by no-slip walls at y = 0 and y = 2H and unbounded in x and z. Quantities referring to a specific component α in the mixture will have subscript α: for example n α is the number density of component α. We consider here only simple shear (plane Couette) flow and, consistent with the diluteness assumption, take the shear rateγ to be independent of the local number densities and thus independent of position. In a dilute suspension of particles, where φ ≪ 1, the particle-particle interactions can be treated as a sequence of uncorrelated pair collisions [17][18][19]. For the moment, we neglect molecular diffusion of the particles. This issue is further addressed below. Since the particles are deformable, they migrate away from the wall during flow with velocity v αm (y) [20,21]. The evolution of the particle number density distributions can be idealized by a kinetic master equation that captures the migration

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Margination Regimes and Drainage Transition in Confined Multicomponent Suspensions

2015

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“…Since this is evidently expedient in platelet functions of hemostasis, there have been intensive studies on the platelet behavior in microvessels, including in vivo and in vitro experiments and numerical model studies. [3][4][5][6][7][8] In general, the Reynolds numbers for the microcirculation are very small.…”

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Cross-Sectional Distributions of Platelet-Sized Particles in Blood Flow through Microchannels

Noso

Kimura

Sakamoto

et al. 2015

J. Soc. Rheol., Jpn

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Simulation of binary dispersion system of droplets with size and surface tension difference under Couette flow

Cited by 2 publications

References 5 publications

Margination Regimes and Drainage Transition in Confined Multicomponent Suspensions

Margination Regimes and Drainage Transition in Confined Multicomponent Suspensions

Cross-Sectional Distributions of Platelet-Sized Particles in Blood Flow through Microchannels

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