Collective dynamics of confined rigid spheres and deformable drops

Janssen, Pieter; Baron, Matthew; Anderson, Patrick Patrick; Bławzdziewicz, Jerzy; Loewenberg, Michael; Wajnryb, Eligiusz

doi:10.1039/c2sm25812a

Cited by 43 publications

(77 citation statements)

References 54 publications

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“…A natural question is how to introduce an effective attraction to the crystalline states, causing particles to assemble from disorder, and providing a 'restoring force' against perturbations. One indication is provided by a recent study which demonstrated stable pairing of droplets via the higher flow disturbance multipoles induced by shape deformation 18 . This finding suggests a key role for particle shape in achieving self-steering and self-organization.…”

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confidence: 99%

Engineering particle trajectories in microfluidic flows using particle shape

2013

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Recent advances in microfluidic technologies have created a demand for techniques to control the motion of flowing microparticles. Here we consider how the shape and geometric confinement of a rigid microparticle can be tailored for 'self-steering' under external flow. We find that an asymmetric particle, weakly confined in one direction and strongly confined in another, will align with the flow and focus to the channel centreline. Experimentally and theoretically, we isolate three viscous hydrodynamic mechanisms that contribute to particle dynamics. Through their combined effects, a particle is stably attracted to the channel centreline, effectively behaving as a damped oscillator. We demonstrate the use of self-steering particles for microfluidic device applications, eliminating the need for external forces or sheath flows.

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confidence: 99%

Engineering particle trajectories in microfluidic flows using particle shape

2013

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“…Janssen et al [13] have studied numerically pairs of rigid spheres and deformable drops driven by a Poiseuille flow through a three-dimensional (3D) rectangular channel in the Stokes regime. Due to the reversibility of Stokes equations, the interdistance between a pair of rigid spheres does not evolve in time.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic pairing of soft particles in a confined flow

et al. 2017

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The mechanism of hydrodynamics-induced pairing of soft particles, namely closed bilayer membranes (vesicles, a model system for red blood cells) and drops, is studied numerically with a special attention paid to the role of the confinement (the particles are within two rigid walls). This study unveils the complexity of the pairing mechanism due to hydrodynamic interactions. We find both for vesicles and for drops that two particles attract each other and form a stable pair at weak confinement if their initial separation is below a certain value. If the initial separation is beyond that distance, the particles repel each other and adopt a longer stable interdistance. This means that for the same confinement we have (at least) two stable branches. To which branch a pair of particles relaxes with time depends only on the initial configuration. An unstable branch is found between these two stable branches. At a critical confinement the stable branch corresponding to the shortest interdistance merges with the unstable branch in the form of a saddle-node bifurcation. At this critical confinement we have a finite jump from a solution corresponding to the continuation of the unbounded case to a solution which is induced by the presence of walls. The results are summarized in a phase diagram, which proves to be of a complex nature. The fact that both vesicles and drops have the same qualitative phase diagram points to the existence of a universal behavior, highlighting the fact that with regard to pairing the details of mechanical properties of the deformable particles are unimportant. This offers an interesting perspective for simple analytical modeling.

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“…Multiphase viscoelastic (EV) fluid flows have been studied much more than EVP flows, and indeed some of the results in literature will be used to validate our numerical implementation. To give a few examples of such studies, we list 2D and 3D direct numerical simulations of the dynamics of a rigid single particle, [31][32][33][34][35] two particles, [36][37][38][39] multiple particles, [40][41][42][43] as well as droplets in viscoelastic two-phase flow systems in which one or both phases could be viscoelastic, [44][45][46] including the case of soft particles modeled as a neo-Hookean solid (ie, a deformable particle is assumed to be a viscoelastic fluid with an infinite relaxation time). 47,48 In the case of a pure visco-plastic (VP) suspending fluid, there is an abundance of computational studies of single and multiple particles.…”

Section: Discussionmentioning

confidence: 99%

Computational modeling of multiphase viscoelastic and elastoviscoplastic flows

Izbassarov

Rosti

Ardekani

et al. 2018

Numerical Methods in Fluids

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Summary In this paper, a three‐dimensional numerical solver is developed for suspensions of rigid and soft particles and droplets in viscoelastic and elastoviscoplastic (EVP) fluids. The presented algorithm is designed to allow for the first time three‐dimensional simulations of inertial and turbulent EVP fluids with a large number particles and droplets. This is achieved by combining fast and highly scalable methods such as an FFT‐based pressure solver, with the evolution equation for non‐Newtonian (including EVP) stresses. In this flexible computational framework, the fluid can be modeled by either Oldroyd‐B, neo‐Hookean, FENE‐P, or Saramito EVP models, and the additional equations for the non‐Newtonian stresses are fully coupled with the flow. The rigid particles are discretized on a moving Lagrangian grid, whereas the flow equations are solved on a fixed Eulerian grid. The solid particles are represented by an immersed boundary method with a computationally efficient direct forcing method, allowing simulations of a large numbers of particles. The immersed boundary force is computed at the particle surface and then included in the momentum equations as a body force. The droplets and soft particles on the other hand are simulated in a fully Eulerian framework, the former with a level‐set method to capture the moving interface and the latter with an indicator function. The solver is first validated for various benchmark single‐phase and two‐phase EVP flow problems through comparison with data from the literature. Finally, we present new results on the dynamics of a buoyancy‐driven drop in an EVP fluid.

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Collective dynamics of confined rigid spheres and deformable drops

Cited by 43 publications

References 54 publications

Engineering particle trajectories in microfluidic flows using particle shape

Engineering particle trajectories in microfluidic flows using particle shape

Hydrodynamic pairing of soft particles in a confined flow

Computational modeling of multiphase viscoelastic and elastoviscoplastic flows

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