Emergent pattern formation of active magnetic suspensions in an external field
| Autor: | Sara Jabbari-Farouji, Fabian R. Koessel |
|---|---|
| Přispěvatelé: | Soft Condensed Matter (ITFA, IoP, FNWI), IoP (FNWI) |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Physics
Hydrodynamic stability Smoluchowski coagulation equation Magnetic moment Field (physics) Statistical Mechanics (cond-mat.stat-mech) General Physics and Astronomy Pattern formation FOS: Physical sciences Pattern Formation and Solitons (nlin.PS) Condensed Matter - Soft Condensed Matter 01 natural sciences Instability Nonlinear Sciences - Pattern Formation and Solitons 010305 fluids & plasmas Magnetic field symbols.namesake Classical mechanics 0103 physical sciences symbols Polar Soft Condensed Matter (cond-mat.soft) 010306 general physics Condensed Matter - Statistical Mechanics |
| Zdroj: | New Journal of Physics, 22(10):103007. IOP Publishing Ltd. |
| ISSN: | 1367-2630 |
| DOI: | 10.1088/1367-2630/abb64d |
| Popis: | We study collective self-organization of weakly magnetic active suspensions in a uniform external field by analyzing a mesoscopic continuum model that we have recently developed. Our model is based on a Smoluchowski equation for a particle probability density function in an alignment field coupled to a mean-field description of the flow arising from the activity and the alignment torque. Performing linear stability analysis of the Smoluchowski equation and the resulting orientational moment equations combined with non-linear 3D simulations, we provide a comprehensive picture of instability patterns as a function of strengths of activity and magnetic field. For sufficiently high activity and moderate magnetic field strengths, the competition between the activity-induced flow and external magnetic torque renders a homogeneous polar steady state unstable. As a result, four distinct dynamical patterns of collective motion emerge. The instability patterns for pushers include traveling bands governed by bend-twist instabilities and dynamical aggregates. For pullers, finite-sized and system spanning pillar-like concentrated regions predominated by splay deformations emerge which migrate in the field direction. Notably, at very strong magnetic fields, we observe a reentrant hydrodynamic stability of the polar steady state. 22 pages, 22 figures |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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