تقرير
Inertia drives a flocking phase transition in viscous active fluids
| العنوان: | Inertia drives a flocking phase transition in viscous active fluids |
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| المؤلفون: | Chatterjee, Rayan, Rana, Navdeep, Simha, R. Aditi, Perlekar, Prasad, Ramaswamy, Sriram |
| المصدر: | Phys. Rev. X 11, 031063 (2021) |
| سنة النشر: | 2019 |
| المجموعة: | Condensed Matter Physics (Other) |
| مصطلحات موضوعية: | Condensed Matter - Soft Condensed Matter, Physics - Biological Physics, Physics - Fluid Dynamics |
| الوصف: | How fast must an oriented collection of extensile swimmers swim to escape the instability of viscous active suspensions? We show that the answer lies in the dimensionless combination $R=\rho v_0^2/2\sigma_a$, where $\rho$ is the suspension mass density, $v_0$ the swim speed and $\sigma_a$ the active stress. Linear stability analysis shows that for small $R$ disturbances grow at a rate linear in their wavenumber $q$, and that the dominant instability mode involves twist. The resulting steady state in our numerical studies is isotropic hedgehog-defect turbulence. Past a first threshold $R$ of order unity we find a slower growth rate, of $O(q^2)$; the numerically observed steady state is {\it phase-turbulent}: noisy but {\it aligned} on average. We present numerical evidence in three and two dimensions that this inertia driven flocking transition is continuous, with a correlation length that grows on approaching the transition. For much larger $R$ we find an aligned state linearly stable to perturbations at all $q$. Our predictions should be testable in suspensions of mesoscale swimmers [D Klotsa, Soft Matter \textbf{15}, 8946 (2019)]. Comment: Version of the manuscript accepted in PRX |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevX.11.031063 |
| URL الوصول: | http://arxiv.org/abs/1907.03492 |
| رقم الأكسشن: | edsarx.1907.03492 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevX.11.031063 |
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