Chapman-Enskog expansion for chirally colliding disks

Ruben Lier; Paweł Matus

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arXiv · 2602.21367

Chapman-Enskog expansion for chirally colliding disks

Ruben Lier·Paweł Matus

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Abstract

We study a two-dimensional fluid of hard disks undergoing chiral, energy- and momentum-conserving collisions. We show that despite the microscopic breaking of time-reversal symmetry, the H-theorem is obeyed, guaranteeing a relaxation towards equilibrium in the absence of external forces. In the dilute limit, a Chapman-Enskog expansion yields analytical expressions for the shear and odd viscosity and the thermal conductivity. Theoretical predictions are confirmed by nonequilibrium molecular dynamics simulations.

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Ruben Lier, Paweł Matus. 2026-02-24. Chapman-Enskog expansion for chirally colliding disks. https://arxiv.org/abs/2602.21367

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