Langevin dynamics encapsulate the microscopic and emergent macroscopic properties of midge swarms

A - Papers appearing in refereed journals

Reynolds, A. M. 2018. Langevin dynamics encapsulate the microscopic and emergent macroscopic properties of midge swarms. Journal of the Royal Society Interface. 15.

AuthorsReynolds, A. M.

In contrast with bird flocks, fish schools and animal herds, midge swarms maintain cohesion but do not process global order. High-speed imaging techniques are now revealing that these swarms have surprisingly properties. Here I show that simple models found on the Langevin equation are consistent with this wealth of recent observations. The models predict correctly that large accelerations, exceeding 10 g, will be common and they predict correctly the co-existence of core condensed phases surrounded by dilute vapour phases. The models also provide new insights into the influence of environmental conditions on swarm dynamics. They predict that correlations between midges increase the strength of the effective force binding the swarm together. This may explain why such correlations are absent in laboratory swarms but present in natural swarms which contend with the wind and other disturbances. Finally, the models predict that swarms have fluid-like macroscopic mechanical properties and will slosh rather than slide back-and-forth after being abruptly displaced. This prediction offers a promising avenue for future experimentation that goes beyond current quasi-static testing which has revealed solid-like responses.

KeywordsSwarming, stochastic modelling, emergent properties
Year of Publication2018
JournalJournal of the Royal Society Interface
Journal citation15
Digital Object Identifier (DOI)
PubMed ID29298958
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeBBSRC Strategic Programme in Smart Crop Protection
BBSRC Strategic Programme in Smart Crop Protection
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
Online03 Jan 2018
Publication process dates
Accepted01 Dec 2017
PublisherRoyal Society Publishing
Copyright licenseCC BY

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