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Main Authors: Ganguly, Arkava, Roychowdhury, Souradeep, Gupta, Ankur
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2402.18861
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author Ganguly, Arkava
Roychowdhury, Souradeep
Gupta, Ankur
author_facet Ganguly, Arkava
Roychowdhury, Souradeep
Gupta, Ankur
contents The mobility of externally-driven phoretic propulsion of particles is evaluated by simultaneously solving the solute conservation equation, interaction potential equation, and the modified Stokes equation. While accurate, this approach is cumbersome, especially when the interaction potential decays slowly compared to the particle size. In contrast to external phoresis, the motion of self-phoretic particles is typically estimated by relating the translation and rotation velocities with the local slip velocity. While this approach is convenient and thus widely used, it is only valid when the interaction decay length is significantly smaller than the particle size. Here, by taking inspiration from Brady J. Fluid Mech. (2021), vol. 922, A10, which combines the benefits of two approaches, we reproduce their unified mobility expressions with arbitrary interaction potentials and show that these expressions can conveniently recover the well-known mobility relationships of external electrophoresis and diffusiophoresis for arbitrary double-layer thickness. Additionally, we show that for a spherical microswimmer, the derived expressions relax to the slip velocity calculations in the limit of the thin interaction lengthscales. We also employ the derived mobility expressions to calculate the velocities of an autophoretic Janus particle. We find that there is significant dampening in the translation velocity even when the interaction length is an order of magnitude larger than the particle size. Finally, we study the motion of a catalytically self-propelled particle, while it also propels due to external concentration gradients, and demonstrate how the two propulsion modes compete with each other.
format Preprint
id arxiv_https___arxiv_org_abs_2402_18861
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Universal Translational and Rotational Mobility Expressions of Phoretic and Self-phoretic Particles with Arbitrary Interaction Potentials
Ganguly, Arkava
Roychowdhury, Souradeep
Gupta, Ankur
Fluid Dynamics
Soft Condensed Matter
The mobility of externally-driven phoretic propulsion of particles is evaluated by simultaneously solving the solute conservation equation, interaction potential equation, and the modified Stokes equation. While accurate, this approach is cumbersome, especially when the interaction potential decays slowly compared to the particle size. In contrast to external phoresis, the motion of self-phoretic particles is typically estimated by relating the translation and rotation velocities with the local slip velocity. While this approach is convenient and thus widely used, it is only valid when the interaction decay length is significantly smaller than the particle size. Here, by taking inspiration from Brady J. Fluid Mech. (2021), vol. 922, A10, which combines the benefits of two approaches, we reproduce their unified mobility expressions with arbitrary interaction potentials and show that these expressions can conveniently recover the well-known mobility relationships of external electrophoresis and diffusiophoresis for arbitrary double-layer thickness. Additionally, we show that for a spherical microswimmer, the derived expressions relax to the slip velocity calculations in the limit of the thin interaction lengthscales. We also employ the derived mobility expressions to calculate the velocities of an autophoretic Janus particle. We find that there is significant dampening in the translation velocity even when the interaction length is an order of magnitude larger than the particle size. Finally, we study the motion of a catalytically self-propelled particle, while it also propels due to external concentration gradients, and demonstrate how the two propulsion modes compete with each other.
title Universal Translational and Rotational Mobility Expressions of Phoretic and Self-phoretic Particles with Arbitrary Interaction Potentials
topic Fluid Dynamics
Soft Condensed Matter
url https://arxiv.org/abs/2402.18861