The dynamics of a capsule in a wall-bounded oscillating shear flow

Zhu, Lailai; Rabault, Jean; Brandt, Luca

doi:10.1063/1.4926675

Cited by 20 publications

(9 citation statements)

References 73 publications

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“…Fig. 4 shows the oscillatory deformation of the capsule [56,57] over time with a frequency twice the flow oscillation frequency since during each pressure gradient period, the capsule reaches maximum or minimum deformation twice [58]. Fig.…”

Section: Methodsmentioning

confidence: 99%

Inertial migration of a deformable capsule in an oscillatory flow in a microchannel

Lafzi,

Raffiee,

Dabiri

2020

Preprint

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Dynamics of a deformable capsule in an oscillatory flow of a Newtonian fluid in a microchannel has been studied numerically. The effects of oscillation frequency, capsule deformability, and channel flow rate have been explored by simulating the capsule within a microchannel. In addition, the simulation captures the effect of the type of imposed pressure oscillations on the migration pattern of the capsule. An oscillatory channel flow enables the focusing of extremely small biological particles by eliminating the need to design impractically long channels. The presented results show that the equilibrium position of the capsule changes not only by the addition of an oscillatory component to the pressure gradient, but it also is influenced by the capsule deformability and channel flow rate. Furthermore, it has been shown that the amplitude of oscillation of capsules decreases as the channel flow rate and the rigidity of the capsule increases.

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Section: Methodsmentioning

confidence: 99%

Inertial migration of a deformable capsule in an oscillatory flow in a microchannel

Lafzi,

Raffiee,

Dabiri

2020

Preprint

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“…The general geometry Ewald-like method (GGEM) also uses an indirect formulation to make the equations amenable to an accelerated computation. This was mostly used for problems where two of the three spacial directions are periodic [3,[69][70][71][72][73][74][75][76]]. Yet, statements regarding existence and uniqueness of the solution are lacking so far.…”

Section: The Volume-changing Object Boundary Integral Methodsmentioning

confidence: 99%

“…This allows for secure travel through the vascular system. Once the volume oscillations are activated after around 4.0 s to model an ultrasound source, the bubbles oscillate periodically in stiffness due to the lipid coating that is modeled according to equation (73). This is in contrast to figure 3 where the surface tension remains constant.…”

Section: Lipid Coated Microbubbles With Radius-dependent Surface Tensionmentioning

confidence: 99%

A boundary integral method with volume-changing objects for ultrasound-triggered margination of microbubbles

Guckenberger

Gekle

2017

J. Fluid Mech.

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A variety of numerical methods exist for the study of deformable particles in dense suspensions. None of the standard tools, however, currently include volume-changing objects such as oscillating microbubbles in three-dimensional periodic domains. In the first part of this work, we develop a novel method to include such entities based on the boundary integral method. We show that the well-known boundary integral equation must be amended with two additional terms containing the volume flux through the bubble surface. We rigorously prove the existence and uniqueness of the solution. Our proof contains as a subset the simpler boundary integral equation without volume-changing objects (such as red blood cell or capsule suspensions) which is widely used but for which a formal proof in periodic domains has not been published to date.In the second part, we apply our method to study microbubbles for targeted drug delivery. The ideal drug delivery agent should stay away from the biochemically active vessel walls during circulation. However, upon reaching its target it should attain a near-wall position for efficient drug uptake. Though seemingly contradictory, we show that lipid-coated microbubbles in conjunction with a localized ultrasound pulse possess precisely these two properties. This ultrasound-triggered margination is due to hydrodynamic interactions between the red blood cells and the oscillating lipid-coated microbubbles which alternate between a soft and a stiff state. We find that the effect is very robust, existing even if the duration in the stiff state is more than three times lower than the opposing time in the soft state.

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“…Janpaen et al (2009) carried out an experimental investigation of droplet deformation and breakup in oscillatory shear flows, where the immiscible components they used are Newtonian fluids as well as the Boger fluids. In addition, there are a few studies focusing on the deformation dynamics of spherical and non-spherical capsules in oscillating shear flow ( Zhao and Bagchi, 2011;Matsunaga et al, 2015;Zhu et al, 2015 ). However, owing to the existence of inner droplet, it was found that compound droplets, compared with single-phase droplets, exhibit different topological structures and more complex behaviors ( Smith et al, 2004;Gao and Feng, 2011;Hua et al, 2014;Luo et al, 2015;Chen et al, 2015b;Borthakur et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Deformation and breakup of a compound droplet in three-dimensional oscillatory shear flow

Liu

et al. 2021

International Journal of Multiphase Flow

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A compound droplet subject to three-dimensional oscillatory shear flow is studied using a three-phase lattice Boltzmann model. Firstly, focusing on low values of capillary number ( Ca ) where the compound droplet eventually reaches steady-state oscillatory condition, we study the effect of oscillatory period, viscosities of inner and outer fluids of the compound droplet, wall confinement and Ca on the droplet behavior. As the oscillatory period increases, the maximum deformation parameters gradually approach the steady-state values in the corresponding simple shear flow for both inner and outer droplets, and the compound droplet is more synchronous with applied shear. We demonstrate for the first time that due to high pressure near two tips inside the outer droplet the inner droplet may rotate counterintuitively in a direction opposite to the outer one. The compound droplet undergoes larger deformation when either droplet is less viscous, which also decreases the synchronization between inner and outer droplets. Increasing confinement ratio not only promotes the deformations of both constituent droplets, but also makes them more synchronous with applied shear. It is also found that the maximum deformation parameters of both droplets increase linearly with Ca up to Ca = 0 . 35 but deviate from the linearity at higher Ca , where multipeaked oscillations are observed for the deformation of the inner droplet, which can be due to the extensional flow resulting from the rapid contraction of the outer droplet. We then analyze the breakup behavior of compound droplet in the oscillatory shear flow for varying confinement ratios, and compare the findings with those in simple shear flow. The critical capillary number for droplet breakup exhibits a non-monotonic behavior with the confinement ratio in both shear flows, but its value is always higher in oscillatory shear flow than in simple shear flow. As the confinement ratio increases, in the case of oscillatory shear flow, the droplet undergoes a transition from inner ternary breakup to inner binary breakup, distinct from the one observed in the case of simple shear flow. Finally, increasing oscillatory period is found to not only decrease the critical capillary number but also change the mode of droplet breakup.

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The dynamics of a capsule in a wall-bounded oscillating shear flow

Cited by 20 publications

References 73 publications

Inertial migration of a deformable capsule in an oscillatory flow in a microchannel

Inertial migration of a deformable capsule in an oscillatory flow in a microchannel

A boundary integral method with volume-changing objects for ultrasound-triggered margination of microbubbles

Deformation and breakup of a compound droplet in three-dimensional oscillatory shear flow

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