Tank-treading of microcapsules in shear flow

Loubens, Clément de; Deschamps, Julien; Edwards-Lévy, Florence; Léonetti, Marc

doi:10.1017/jfm.2015.758

Cited by 33 publications

(33 citation statements)

References 46 publications

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“…Interestingly, Yazdani & Bagchi (2013) have studied the contribution of shear surface viscosity to the dynamics of capsules. They showed notably that the period of tank-treading varies with membrane viscosity, a result recently confirmed by experimental investigations on HSA microcapsules (de Loubens et al 2015b). However, the computation of bending stiffness was found to be necessary for capsules, in order to suppress wrinkling.…”

Section: Introductionmentioning

confidence: 79%

Influence of surface viscosity on droplets in shear flow

et al. 2016

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The behaviour of a single droplet in an immiscible external fluid, submitted to shear flow is investigated using numerical simulations. The surface of the droplet is modelled by a Boussinesq-Scriven constitutive law involving the interfacial viscosities and a constant surface tension. A numerical method using Loop subdivision surfaces to represent droplet interface is introduced. This method couples boundary element method for fluid flows and finite element method to take into account the stresses due to the surface dilational and shear viscosities and surface tension. Validation of the numerical scheme with respect to previous analytic and computational work is provided, with particular attention to the viscosity contrast and the shear and dilational viscosities characterized both by a Boussinesq number B q . Then, influence of equal surface viscosities on steady-state characteristics of a droplet in shear flow are studied, considering both small and large deformations and for a large range of bulk viscosity contrast. We find that small deformation analysis is surprisingly predictive at moderate and high surface viscosities. Equal surface viscosities decrease the Taylor deformation parameter and tank-treading angle and also strongly modify the dynamics of the droplet: when the Boussinesq number (surface viscosity) is large relative to the capillary number (surface tension), the droplet displays damped oscillations prior to steady-state tank-treading, reminiscent from the behaviour at large viscosity contrast. In the limit of infinite capillary number Ca, such oscillations are permanent. The influence of surface viscosities on breakup is also investigated, and results show that the critical capillary number is increased. A diagram (B q ; Ca) of breakup is established with the same inner and outer bulk viscosities. Additionally, the separate roles of shear and dilational surface viscosity are also elucidated, extending results from small deformation analysis. Indeed, shear (dilational) surface viscosity increases (decreases) the stability of drops to breakup under shear flow. The steady-state deformation (Taylor parameter) varies nonlinearly with each Boussinesq number or a linear combination of both Boussinesq numbers. Finally, the study shows that for certain combinations of shear and dilational viscosities, drop deformation for a given capillary number is the same as in the case of a clean surface while the inclination angle varies.

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Section: Introductionmentioning

confidence: 79%

Influence of surface viscosity on droplets in shear flow

et al. 2016

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“…The determination of the surface viscous modulus of the membrane is out of the scope of this paper. This parameter is difficult to determine by experiments on microcapsules as we need to track the movement of the membrane in shear flow and deduce the viscous modulus from inverse numerical simulations 22,41 .…”

Section: Elongation Flow Chambermentioning

confidence: 99%

“…More recently, these methods have been extended to micrometric capsules [34][35][36][37][38] . By combination with advanced numerical simulations 21,22,39 , the nonlinear elastic constitutive laws in regime of large deformation 40 and the viscosity of the membrane 41 have been determined for microcapsules made from a biopolymer (HSA) that was physically cross-linked to form a thin membrane in hydrogel. It was shown that this kind of microcapsules can sustained up to 180% of stretching without plastic deformations or break-up.…”

Section: Introductionmentioning

confidence: 99%

Interfacial rheological properties of self-assembling biopolymer microcapsules

et al. 2017

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Tuning the mechanical properties of microcapsules through a cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step. This thorough study provides new insights into the mechanics of these weakly cohesive membranes. Firstly, suspensions of water-in-oil microcapsules were formed in microfluidic junctions by self-assembly of two oppositely charged polyelectrolytes, namely chitosan (water soluble) and phosphatidic fatty acid (oil soluble). In this way, composite membranes of tunable thickness (between 40 and 900 nm measured by AFM) were formed at water/oil interfaces in a single step by changing the composition. Secondly, microcapsules were mechanically characterized by stretching them up to break-up in an extensional flow chamber which extends the relevance and convenience of the hydrodynamic method to weakly cohesive membranes. Finally, we show that the design of microcapsules can be 'engineered' in an extensive way since they present a wealth of interfacial rheological properties in terms of elasticity, plasticity and yield stress whose magnitudes can be controlled by the composition. These behaviors are explained by the variation of the membrane thickness with the physico-chemical parameters of the process.

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“…It is then straightforward to construct matrix form of the relations between on the one hand limit values of tension ({γ}) and limit values of tension forces ({f γ }), and on the other hand, between limit values of velocities ({v}) and limit values of surface divergence ({∇ s • v}). To finish the approximation of D γ , the linear relation between limit values of forces ({f }) and limit values of velocities ({v}) expressed by (16) without viscosity contrast (λ = 1) is discretized over the linear mesh as in [7] by using Gauss-Hammer quadrature for non-singular elements and Gauss-Legendre quadrature with polar coordinates for singular elements. Thus, with the matrices F γ , D, G defined by the preconditioner D γ is defined as…”

Section: Surface Incompressibility Constraint Solvermentioning

confidence: 99%

Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow

Boëdec

Léonetti

Jaeger

2017

Journal of Computational Physics

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International audienceWe develop an algorithm for the three dimensional simulation of the dynamics of soft objects (drops, capsules, vesicles) under creeping flow conditions. Loop elements are used to describe the shape of the soft objects. This surface representation is used both for membrane solver based on finite element method (FEM) and for the fluid solver based on the boundary element method (BEM). This isogeometric analysis of the low Reynolds fluid-structure interaction problem is then coupled to high-order explicit time stepping or second-order implicit time stepping algorithm. For vesicles simulation, a preconditioner is designed for the resolution of the surface velocity incompressibility constraint, which is treated by the use of a local Lagrange multiplier. A mesh quality preserving algorithm is introduced to improve the control mesh quality over long simulation times. We test the proposed algorithm on capsule and vesicle dynamics in various flows, and study its convergence properties, showing a second-order convergence O(N-2) with mesh number of elements

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Tank-treading of microcapsules in shear flow

Abstract: International audienc

Cited by 33 publications

References 46 publications

Influence of surface viscosity on droplets in shear flow

Influence of surface viscosity on droplets in shear flow

Interfacial rheological properties of self-assembling biopolymer microcapsules

Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow

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