Hydrodynamic interactions in dense active suspensions: from polar order to dynamical clusters
arXiv:1706.02875 · doi:10.1103/PhysRevE.96.020603
Abstract
We study the role of hydrodynamic interactions in the collective behaviour of collections of microscopic active particles suspended in a fluid. We introduce a novel calculational framework that allows us to separate the different contributions to their collective dynamics from hydrodynamic interactions on different length scales. Hence we are able to systematically show that lubrication forces when the particles are very close to each other play as important a role as long-range hydrodynamic interactions in determining their many-body behaviour. We find that motility-induced phase separation is suppressed by near-field interactions, leading to open gel-like clusters rather than dense clusters. Interestingly, we find a globally polar ordered phase appears for neutral swimmers with no force dipole that is enhanced by near field lubrication forces in which the collision process rather than long-range interaction dominates the alignment mechanism.
7 pages, 4 figures
References in corpus (10)
- Novel type of phase transition in a system of self-driven particles
- Meso-scale turbulence in living fluids
- Propulsion of a molecular machine by asymmetric distribution of reaction--products
- Hydrodynamics of self-propulsion near a boundary: predictions and accuracy of far-field approximations
- Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?
- Non-equilibrium clustering of self-propelled rods
- Orientational order in concentrated suspensions of spherical microswimmers
- Spontaneous aggregation and global polar ordering in squirmer suspensions
- Dynamic regimes of hydrodynamically coupled self-propelling particles
- Morphology of clusters of attractive dry and wet self-propelled spherical particle suspensions