Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane

We use a flexible circular membrane to probe a gas of macroscopic self-propelled rod-like robots. The fluctuations of the membrane are completely described by a set of discrete modes with different characteristic frequencies. We show that the dynamics of each mode can be well described by a Langevin...

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Main Authors: Jean François Boudet, Julie Jagielka, Thomas Guerin, Thomas Barois, Fabio Pistolesi, Hamid Kellay
Format: Article
Language:English
Published: American Physical Society 2022-10-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.4.L042006
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author Jean François Boudet
Julie Jagielka
Thomas Guerin
Thomas Barois
Fabio Pistolesi
Hamid Kellay
author_facet Jean François Boudet
Julie Jagielka
Thomas Guerin
Thomas Barois
Fabio Pistolesi
Hamid Kellay
author_sort Jean François Boudet
collection DOAJ
description We use a flexible circular membrane to probe a gas of macroscopic self-propelled rod-like robots. The fluctuations of the membrane are completely described by a set of discrete modes with different characteristic frequencies. We show that the dynamics of each mode can be well described by a Langevin equation with a white noise and a frequency-independent dissipation. This allows to extract the dissipation and fluctuation intensity for each mode, and consequently the contribution to the dissipation due to the collisions with the gas. The ratio of the gas-generated fluctuation and dissipation does not depend on the mode, indicating that the system interacts with the membrane as an equilibrium environment at a given effective temperature. We also find that this effective temperature coincides with the average kinetic energy of the rod-like robots. Quite surprisingly, this study thus shows that in a wide range of densities and frequencies the behavior of self-propelled robots can be regarded as that of an equilibrium gas. The method is quite general, and can be used to unveil deviations from this simple behavior in other regimes.
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spelling doaj.art-547b30b9464941dba7f9381e376638212024-04-12T17:25:08ZengAmerican Physical SocietyPhysical Review Research2643-15642022-10-0144L04200610.1103/PhysRevResearch.4.L042006Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membraneJean François BoudetJulie JagielkaThomas GuerinThomas BaroisFabio PistolesiHamid KellayWe use a flexible circular membrane to probe a gas of macroscopic self-propelled rod-like robots. The fluctuations of the membrane are completely described by a set of discrete modes with different characteristic frequencies. We show that the dynamics of each mode can be well described by a Langevin equation with a white noise and a frequency-independent dissipation. This allows to extract the dissipation and fluctuation intensity for each mode, and consequently the contribution to the dissipation due to the collisions with the gas. The ratio of the gas-generated fluctuation and dissipation does not depend on the mode, indicating that the system interacts with the membrane as an equilibrium environment at a given effective temperature. We also find that this effective temperature coincides with the average kinetic energy of the rod-like robots. Quite surprisingly, this study thus shows that in a wide range of densities and frequencies the behavior of self-propelled robots can be regarded as that of an equilibrium gas. The method is quite general, and can be used to unveil deviations from this simple behavior in other regimes.http://doi.org/10.1103/PhysRevResearch.4.L042006
spellingShingle Jean François Boudet
Julie Jagielka
Thomas Guerin
Thomas Barois
Fabio Pistolesi
Hamid Kellay
Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
Physical Review Research
title Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
title_full Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
title_fullStr Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
title_full_unstemmed Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
title_short Effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
title_sort effective temperature and dissipation of a gas of active particles probed by the vibrations of a flexible membrane
url http://doi.org/10.1103/PhysRevResearch.4.L042006
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