Modified Enskog equation for hard rods

Vir B. Bulchandani

Published 2023-09-27Version 1

We point out that Percus's collision integral for hard rods [J. K. Percus, Physics of Fluids 12, 1560-1563 (1969)] does not preserve the thermal equilibrium state in an external trapping potential. We derive a modified Enskog equation for hard rods and show that it preserves this thermal state exactly. In contrast to recent proposed kinetic equations for dynamics in integrability-breaking traps, both our kinetic equation and its thermal states are explicitly nonlocal in space. Our equation differs from earlier proposals at third order in spatial derivatives and we attribute this discrepancy to the molecular chaos assumption underlying our approach.