Adhesion and detachment of a capsule in axisymmetric flow

Abstract

The adhesion and detachment of a capsule on a solid boundary surface is studied via a combination of scaling theory and numerical simulation and the behavior is compared and contrasted with a vesicle. It is shown that the dominant physical property for both capsules and vesicles is the area dilation modulus K s of the membrane. The nonzero shear modulus G s for capsules increases the resistance to deformation and thus decreases slightly the equilibrium contact radius for an adhered capsule compared to an adhered vesicle. The detachment process in this study is due to an external axisymmetric flow. Unlike a rigid body that must be pulled away without change of shape, capsules (and vesicles) almost always detach dominantly by peeling in which the contact radius decreases but the minimum separation distance does not change until the final moments of detachment. Compared to a vesicle with the same K s , a capsule maintains a more compact shape and is harder to elongate under a given external flow. Hence, the detachment process is slower for capsules compared to vesicles with the same K s .

Elastic deformation during dynamic force measurements in viscous fluids

“…In absence of a moving spring which limits the surface movement, many experiments involving the bouncing of a sphere have been conducted to validate the EHD theory. These studies are important in the context of collisions, [28,37,38] as well as in hydrodynamic detachment for applications such as filtration, surface cleaning, and biological adhesion [22] Additional studies investigated the surface interactions and contact behaviors of viscous and viscoelastic thin films.…”

Hydrodynamics and rheology of a vesicle doublet suspension

“…The electrostatic nature of lipid molecules (a hydrophobic tail and a hydrophilic head with an electric dipole) complicates the interactions between a lipid bilayer membrane and another bilayer membrane [40][41][42][43] or a solid (such as a glass substrate or a nano particle). Adhesion between a vesicle and a solid has been extensively studied with more focus on the static equilibrium shapes [44][45][46][47][48][49][50][51][52][53][54][55][56] than the transient adhesion process [57][58][59]. Adhesive interactions between lipid membranes are essential in many biomedical, biological, and biophysical processes.…”

Similarity solutions in elastohydrodynamic bouncing

“…Our model focuses on one of the most simple systems, but many effects important in real impacts could be implemented, e.g. surface roughness (Wang & Frechette 2018), viscoelasticity (Pandey et al 2016) and adhesion (Keh & Leal 2016). An interesting extension of this work would be to consider oblique collisions (Joseph & Hunt 2004; Mindlin & Deresiewicz 2021) and investigate the torque generated by the shear forces during the contact.…”