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Article Dans Une Revue Physical Review Fluids Année : 2024

Self-organization of autophoretic suspensions in confined shear flows

Prathmesh Vinze
Sebastien Michelin
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Résumé

Janus phoretic particles exploit chemical energy stored in their environment to produce mechanical work on the surrounding fluid and self-propel. These active particles modify and respond to their hydrodynamic and chemical environments, thus providing them with a sensibility to external flows and other particles. These chemical and hydrodynamic interparticle interactions are known to lead to nontrivial collective behavior within such biological or synthetic active suspensions (e.g., cluster formation of phoretic particles or bacterial swarming). Recent experiments and analysis have demonstrated that the response of active suspensions to shear flows is nontrivial and can, in fact, lead to significant reductions in viscosity due to the energy conversion at microscopic scales. In this work we numerically analyze using a continuum kinetic model the dynamics and response to shear of dilute and confined suspensions of chemotactic phoretic particles that reorient and drift toward the chemical solutes released by their neighbors. We show that a 1D transient steady distribution driven by the effect of confinement is a common feature for the confinement and shear rate intensities considered. This 1D state is stable for strong confinement and thus observed in the long-term dynamics in sufficiently narrow channels. For wider channels, the transient state becomes unstable to streamwise perturbations due to the chemotactic instability, leading to the formation of particle aggregates along the channel's walls. Their relative arrangements and dynamics are determined by the relative influence of shear intensity and chemotaxis and critically condition the suspension's dynamics and particle-induced flows. In a second step, the feedback effect on the flow and effective viscosity of the self-organized suspension is considered. We show that the induced flow and, consequently, its rheological behavior strongly depend on the self-organization regime, and therefore on the interplay of confinement, shear, and chemotaxis.
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Dates et versions

hal-04423466 , version 1 (29-01-2024)

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Prathmesh Vinze, Sebastien Michelin. Self-organization of autophoretic suspensions in confined shear flows. Physical Review Fluids, 2024, 9 (1), pp.014202. ⟨10.1103/PhysRevFluids.9.014202⟩. ⟨hal-04423466⟩
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