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Clausius relation for Active Particles
Andrea Puglisi * 1 , Umberto Marini Bettolo Marconi 2
1  Consiglio Nazionale delle Richerche (CNR) - Istituto dei Sistemi Complessi (ISC) c/o Dipartimento di Fisica, Universita' Sapienza, p.le A. Moro 2 - 00185 - Roma - Italia
2  Universita' di Camerino - via Madonna delle Carceri - Camerino - Italia


Many kinds of active particles, such as bacteria or active colloids, move in a thermostatted fluid by means of self-propulsion. Energy injected by such a non-equilibrium force is eventually dissipated as heat in the thermostat. Since thermal fluctuations are much faster and weaker than self-propulsion forces, they are often neglected, blurring the identification of dissipated heat in theoretical models. For the same reason, some freedom—or arbitrariness—appears when defining entropy production. Recently three different recipes to define heat and entropy production have been proposed for the same model where the role of self-propulsion is played by a Gaussian coloured noise. Here we compare and discuss the relation between such proposals and their physical meaning. One of these proposals takes into account the heat exchanged with a non-equilibrium active bath: such an “active heat” satisfies the original Clausius relation and can be experimentally verified.

Keywords: active particles, Clausius relation, entropy production
Comments on this paper
Miguel Rubi
Clausius relation for active particles
This is an interesting piece of research. Thermodynamics and statistical mechanics have been constructed under the basis that particles are not autonomous. For active particles, one has to revise concepts such as work, heat and temperature. This presentation contributes to set up a thermodynamics of systems composed of active particles by proposing a new Clausius relation to study basic processes taking place in these systems.

Andrea Puglisi
Thanks for the nice comment. I agree that one needs more refined concepts for work, heat and temperature, when coping with active particles.