paper

Entropy production for velocity-dependent macroscopic forces: the problem of dissipation without fluctuations

arXiv:1505.00915 · doi:10.1209/0295-5075/111/40012

Abstract

In macroscopic systems, velocity-dependent phenomenological forces are used to model friction, feedback devices or self-propulsion. Such forces usually include a dissipative component which conceals the fast energy exchanges with a thermostat at the environment temperature , ruled by a microscopic Hamiltonian . The mapping - even if effective for many purposes - may lead to applications of stochastic thermodynamics where an fluctuating entropy production (FEP) is derived. An enlightening example is offered by recent macroscopic experiments where dissipation is dominated by solid-on-solid friction, typically modelled through a deterministic Coulomb force . Through an adaptation of the microscopic Prandtl-Tomlinson model for friction, we show how the FEP is dominated by the heat released to the -thermostat, ignored by the macroscopic Coulomb model. This problem, which haunts several studies in the literature, cannot be cured by weighing the time-reversed trajectories with a different auxiliary dynamics: it is only solved by a more accurate stochastic modelling of the thermostat underlying dissipation.

6 pages, 3 figures

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