The viscous drag of spheres and filaments moving in membranes or monolayers

The dynamics of colloidal particles at interfaces between two fluids plays a central role in microrheology, encapsulation, emulsification, biofilm formation, water remediation and the interface-driven assembly of materials. Common intuition corroborated by hydrodynamic theories suggests that such dynamics is governed by a viscous force lower than that observed in the more viscous fluid. Here, we show experimentally that a particle straddling an air/water interface feels a large viscous drag that is unexpectedly larger than that measured in the bulk. We suggest that such a result arises from thermally activated fluctuations of the interface at the solid/air/liquid triple line and their coupling to the particle drag through the fluctuation-dissipation theorem. Our findings should inform approaches for improved control of the kinetically driven assembly of anisotropic particles with a large triple-line-length/particle-size ratio, and help to understand the formation and structure of such arrested materials.

show abstract

“…To evaluate γ T,H we use the theory provided in ref. 9. We verified that the other theories give similar values (Fig.…”

supporting

confidence: 79%

Brownian diffusion of a partially wetted colloid

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Past studies using either boundary integral 15,16 , finite element 17,18 or integral transform methods 12,19 have focused on the translation, and have assumed that the colloid does not rotate due to the presence of surface roughness or chemical heterogeneities that pin the three-phase contact line (contact angle hysteresis). However recently, evaluating the drag exerted on non-smooth colloids 14 with heterogeneous surfaces as they diffuse along an interface while specifically examining the role of contact line pinning and de-pinning have been important given the extensive interest in particle-laden interfaces.…”

Section: Introductionmentioning

confidence: 99%

The Translational and Rotational Dynamics of a Colloid Moving Along the Air-Liquid Interface of a Thin Film

Das

Koplik

Farinato

et al. 2018

Sci Rep

View full text Add to dashboard Cite

This study examines the translation and rotation of a spherical colloid straddling the (upper) air/liquid interface of a thin, planar, liquid film bounded from below by either a solid or a gas/liquid interface. The goal is to obtain numerical solutions for the hydrodynamic flow in order to understand the influence of the film thickness and the lower interface boundary condition. When the colloid translates on a film above a solid, the viscous resistance increases significantly as the film thickness decreases due to the fluid-solid interaction, while on a free lamella, the drag decreases due to the proximity to the free (gas/liquid) surface. When the colloid rotates, the contact line of the interface moves relative to the colloid surface. If no-slip is assumed, the stress becomes infinite and prevents the rotation. Here finite slip is used to resolve the singularity, and for small values of the slip coefficient, the rotational viscous resistance is dominated by the contact line stress and is surprisingly less dependent on the film thickness and the lower interface boundary condition. For a colloid rotating on a semi-infinite liquid layer, the rotational resistance is largest when the colloid just breaches the interface from the liquid side.

show abstract

“…Especially the dependence of f on Θ could help explain experimental data showing an unexpected scaling of f with the particle size (Wang et al 2011;Du et al 2012), since Θ is modified by line-tension effects, which become especially prominent on small scales. A variety of theoretical and experimental studies deal with the drag coefficient of particles attached to fluid-fluid interfaces (Fulford & Blake 1986;O'Neill, Ranger & Brenner 1986;Danov et al 1995Danov et al , 1998Petkov et al 1995;Cichocki et al 2004;Fischer, Dhar & Heinig 2006;Pozrikidis 2007;Ally & Amirfazli 2010;Bławzdziewicz, Ekiel-Jeżewska & Wajnryb 2010). However, the corresponding theoretical models mostly rely on numerical methods.…”

Section: Introductionmentioning

confidence: 99%

Drag and diffusion coefficients of a spherical particle attached to a fluid–fluid interface

et al. 2016

View full text Add to dashboard Cite

Explicit analytical expressions for the drag and diffusion coefficients of a spherical particle attached to the flat interface between two immiscible fluids are constructed for the case of a vanishing viscosity ratio between the fluid phases. The model is designed to account explicitly for the dependence on the contact angle between the two fluids and the solid surface. The Lorentz reciprocal theorem is applied in the context of geometric perturbations from the limiting cases of 90 • and 180 • contact angles. The model agrees well with the experimental and numerical data from the literature. Also, an advantage of the method utilized is that the drag and diffusion coefficients can be calculated up to one order higher in the perturbation parameter than the known velocity and pressure fields. Extensions to other particle shapes with known velocity and pressure fields are straightforward.

show abstract

The viscous drag of spheres and filaments moving in membranes or monolayers

Cited by 132 publications

References 29 publications

Brownian diffusion of a partially wetted colloid

Brownian diffusion of a partially wetted colloid

The Translational and Rotational Dynamics of a Colloid Moving Along the Air-Liquid Interface of a Thin Film

Drag and diffusion coefficients of a spherical particle attached to a fluid–fluid interface

Contact Info

Product

Resources

About