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Pairing of Lyapunov Exponents for a Hard-Sphere Gas under Shear in the Thermodynamic Limit

Debabrata Panja·Ramses van Zon
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Abstract

We consider a dilute gas of hard spheres under shear. We use one of the predominant models to study this system, namely the SLLOD equations of motion, with an iso-kinetic Gaussian thermostat in between collisions, to get a stationary total peculiar kinetic energy. Based on the previously obtained result that in the non-equilibrium steady state and in case the number of particles $N$ becomes large, the coefficient of dynamical friction representing the iso-kinetic Gaussian thermostat for the SLLOD dynamics fluctuates with $1/\sqrt{N}$ fluctuations around a fixed value, we show on analytical grounds that for a hard sphere gas at small shear rate and with a large number of spheres, the conjugate pairing of the Lyapunov exponents is expected to be violated at the fourth power of the constant shear rate in the bulk.

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Debabrata Panja, Ramses van Zon. 2002-05-30. Pairing of Lyapunov Exponents for a Hard-Sphere Gas under Shear in the Thermodynamic Limit. https://doi.org/10.1103/physreve.66.021101

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