Brownian motion at liquid-gas interfaces. 1. Diffusion coefficients of macroparticles at pure interfaces

Radoev, B.; Nedyalkov, M.; Dyakovich, V.

doi:10.1021/la00048a019

Cited by 33 publications

(38 citation statements)

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“…( 3.17) As expected, if ε = 0, the drag is half the Stokes drag of a sphere (Radoev et al 1992;Danov et al 1995;Ally & Amirfazli 2010). Equally intuitive is the increase in drag with increasing ε, that is deeper immersion of the particle in fluid 1.…”

Section: Flow Field and Stress Distributionmentioning

confidence: 72%

Driven particles at fluid interfaces acting as capillary dipoles

Dörr

Hardt

2015

J. Fluid Mech.

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The dynamics of spherical particles driven along an interface between two immiscible fluids is investigated asymptotically. Under the assumptions of a pinned three-phase contact line and very different viscosities of the two fluids, a particle assumes a tilted orientation. As it moves, it causes a deformation of the fluid interface which is also computed. The case of two interacting driven particles is studied via the Linear Superposition Approximation. It is shown that the capillary interaction force resulting from the particle motion is dipolar in terms of the azimuthal angle and decays with the fifth power of the inter-particle separation, similar to a capillary quadrupole originating from undulations of the threephase contact line. The dipolar interaction is demonstrated to exceed the quadrupolar interaction at moderate particle velocities.

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Section: Flow Field and Stress Distributionmentioning

confidence: 72%

Driven particles at fluid interfaces acting as capillary dipoles

Dörr

Hardt

2015

J. Fluid Mech.

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“…Therefore, the interaction force can be obtained by determining the drag force, which can be calculated using the Stokes equation:51 where η is the viscosity of the fluid, d is the diameter of the particle, and f d denotes the dimensionless drag coefficient for a particle trapped at a fluid–fluid interface. As will be shown below, approximately half of a Janus bubble is submerged under water; thus, we use 0.5 for f d 52, 53. The interaction potential is calculated as the integral of the drag force over the interparticle distance, R (i.e., $ U\left(R \right) = \int {F}_{{\rm inter}} {dR} $ ).…”

Section: Resultsmentioning

confidence: 99%

Generation of Amphiphilic Janus Bubbles and Their Behavior at an Air–Water Interface

Brugarolas

Park

Lee

et al. 2011

Adv Funct Materials

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This paper presents the generation of amphiphilic Janus bubbles and their behavior at an air–water interface. Janus bubbles are generated by selectively depositing gold onto one side of dried nanoparticle‐shelled bubbles. To generate nanoparticle‐shelled bubbles that can withstand drying without significant changes in their structure, it is critical to control the ratio of bubble radius to shell thickness using a microfluidic technique. It is observed that the behavior of Janus bubbles at an air–water interface is very different from that of unmodified nanoparticle‐shelled bubbles. Interfacial assembly of amphiphilic Janus bubbles shows that they interact with one another via long‐ranged attractions. The origin of this long‐ranged attraction is quadrupolar capillary interactions due to the undulation of the three‐phase contact line around the Janus boundary. The interparticle forces between interface‐trapped Janus bubbles are determined using a particle tracking method. The shape of the deformed air–water interface around Janus bubbles is directly observed as well as the orientation of Janus bubbles using a gel‐trapping technique. These observations verify that the air–water interface is pinned around the boundary between the two hemispheres and that the chemical heterogeneity of this boundary leads to irregular contact line around Janus bubbles.

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“…In our experiment the oil drops were shaped as spherical lenses 25 with the surface radii defined by surface tension coefficients (see Supplementary Section S4 for details). Although drag and electromagnetic forces may alter the shapes of soft dielectric interfaces 16,24 , the surface tension forces in our experiment are much larger (Supplementary Section S4) and do not allow significant deformation to the shape of the oil drops 26,27 . Using a ray-tracing method (Fig.…”

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confidence: 87%