Phases and excitations of active rod-bead mixtures: simulations and experiments.
@article{Soni2020PhasesAE, title={Phases and excitations of active rod-bead mixtures: simulations and experiments.}, author={Harsh Soni and Nitin Kumar and Jyothishraj Nambisan and Rahul K Gupta and A. K. Sood and Sriram Ramaswamy}, journal={Soft matter}, year={2020} }
We present a large-scale numerical study, supplemented by experimental observations, on a quasi-two-dimensional active system of polar rods and spherical beads confined between two horizontal plates and energised by vertical vibration. For a low rod concentration Φr, our observations are consistent with a direct phase transition, as bead concentration Φb is increased, from the isotropic phase to a homogeneous flock. For Φr above a threshold value, an ordered band dense in both rods and beads…
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References
SHOWING 1-10 OF 53 REFERENCES
Swimmer Suspensions on Substrates: Anomalous Stability and Long-Range Order.
- PhysicsPhysical review letters
- 2020
It is shown that, depending on the sign of a single parameter, a state with polar orientational order is anomalously stable (or anomalously unstable), with a nonzero relaxation rate for angular fluctuations, not parallel to the ordering direction, at zero wave number.
Nonequilibrium steady states in a vibrated-rod monolayer: tetratic, nematic, and smectic correlations
- Physics
- 2005
We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction.…
Flocking at a distance in active granular matter
- PhysicsNature Communications
- 2014
It is reported here that millimetre-sized tapered rods, rendered motile by contact with an underlying vibrated surface and interacting through a medium of spherical beads, undergo a phase transition to a state of spontaneous alignment of velocities and orientations above a threshold bead area fraction.
Low-noise phase of a two-dimensional active nematic system.
- PhysicsPhysical review. E
- 2018
This work systematically study the two-dimensional fluctuating ordered phase in a coarse-grained hydrodynamic description involving both the nematic director and the conserved density field, showing that the system always displays only quasi-long-ranged orientational order beyond a crossover scale.
Vibrated polar disks: spontaneous motion, binary collisions, and collective dynamics
- Physics
- 2012
We study the spontaneous motion, binary collisions, and collective dynamics of “polar disks”, i.e. specially designed particles which, when vibrated between two horizontal plates, move coherently…
Long-range ordering of vibrated polar disks.
- PhysicsPhysical review letters
- 2013
This work presents a model reproducing quantitatively the single, binary, and collective properties of this granular system usingibrated polar disks, and shows in silico that true long-range order is possible in the experimental system.
Defect Unbinding in Active Nematics.
- PhysicsPhysical review letters
- 2018
It is shown that activity, within perturbation theory, lowers the defect-unbinding transition temperature, determining a critical line in the temperature-activity plane that separates the quasi-long-range ordered (nematic) and disordered (isotropic) phases.
The low noise phase of a 2d active nematic
- Physics
- 2017
We consider a collection of self-driven apolar particles on a substrate that organize into an active nematic phase at sufficiently high density or low noise. Using the dynamical renormalization…
Active nematics on a substrate: Giant number fluctuations and long-time tails
- Physics
- 2003
We construct the equations of motion for the coupled dynamics of order parameter and concentration for the nematic phase of driven particles on a solid surface, and show that they imply i) giant…
Sounds and hydrodynamics of polar active fluids
- PhysicsNature Materials
- 2018
It is demonstrated that two mixed modes, coupling density and velocity fluctuations, propagate along all directions in colloidal-roller fluids and it is shown how the six material constants defining the linear hydrodynamics of these active liquids can be measured from their spontaneous fluctuation spectrum, while being out of reach of conventional rheological methods.