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The behavior of permeable, elastic particles sliding along a repulsive wall is examined computationally. It is found that particles will stick or slip depending on the interplay of elastohydrodynamic and repulsive forces, and the flow in the porous particle. Particles slip when either the elastohydrodynamic lift or repulsive forces are large and create a supporting lubricating film of fluid. However, for lower values of elastohydrodynamic lift or repulsive forces, the flow within the porous particle reduces the pressure in the thin film, resulting in the particles making contact and sticking to the surface. The criteria for the slip-stick transition is presented, which can be used to design systems to promote or suppress slip for such suspensions.
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Formation of a colloidal band via pH‐dependent electrokinetics
Abstract Electroosmosis on nonuniformly charged surfaces often gives rise to intriguing flow behaviors, which can be utilized in applications such as mixing processes and designing micromotors. Here, we demonstrate nonuniform electroosmosis induced by electrochemical reactions. Water electrolysis creates pH gradients near the electrodes that cause a spatiotemporal change in the wall zeta potential, leading to nonuniform electroosmosis. Such nonuniform EOFs induce multiple vortices, which promote the continuous accumulation of particles that subsequently form a colloidal band. The band develops vertically into a “wall” of particles that spans from the bottom to the top surface of the chamber. Such a flow‐driven colloidal band can be potentially used in colloidal self‐assembly and separation processes irrespective of the particle surface properties. For instance, we demonstrate these vortices can promote rapid segregation of soft colloids such as oil droplets and fat globules.
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- Award ID(s):
- 2200882
- PAR ID:
- 10367050
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ELECTROPHORESIS
- Volume:
- 42
- Issue:
- 21-22
- ISSN:
- 0173-0835
- Format(s):
- Medium: X Size: p. 2356-2364
- Size(s):
- p. 2356-2364
- Sponsoring Org:
- National Science Foundation
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