The flow of pedestrians through corridors such as those found in London’s Tube system during rush hour is typically controlled by signs asking everyone to “keep left.” However, this flow is often disordered and subject to clogging. Could there be a way to ensure that everyone keeps left automatically? Indeed, certain shapes of the corridors’ walls might help. Using numerical simulations and analytical calculations of the motion of self-propelling particles through channels with differently shaped walls, researchers from Universidade Federal do Ceará (Claudio L. N. Oliveira and J. S. Andrade), Universidade de São Paulo (A. P. Vieira) and ETH-Zurich (D. Helbing, and H. J. Herrmann) precisely determine the conditions in which self-organized lanes break the left-right symmetry and attach to the left wall because of a ratchetlike effect.
The researchers model a system of self-driven particles traversing a channel, and we impose a zigzag shape to the channel walls. The zigzag walls are characterized by an asymmetry parameter; this parameter modulates the deflection of particles by the walls and results in the particle flows exhibiting preferential sides. The work furthermore takes into account “stubborn” particles that insist on walking on the right-hand side. The team find that the particles are able to spontaneously “keep left” thanks to the zigzag shape of the walls. This transition occurs as a function of density, disorder, and channel width and exhibits unexpected reentrant and inversion effects.
These findings could inform the design of both microfluidics channels and human-scale transit stations.
The full reference of the paper is:
Keep-Left Behavior Induced by Asymmetrically
Profiled Walls C. L. N. Oliveira, A. P. Vieira, D. Helbing, J. S. Andrade, Jr., and H. J.
Herrmann. Phys. Rev. X 6, 011003 (2016).
Source: American Physical Society