Hydrodynamic energy flux in a many-particle system

In this letter, using energy transfers, we demonstrate a route to thermalization in an isolated ensemble of realistic gas particles. We performed a grid-free classical molecular dynamics simulation of two-dimensional Lenard-Jones gas. We start our simulation with a large-scale vortex akin to a hydrodynamic flow and study its non-equilibrium behavior till it attains thermal equilibrium. In the intermediate phases, small wavenumbers (\(k\)) exhibit \(E(k) \propto k^{-3}\) kinetic energy spectrum whereas large wavenumbers exhibit \(E(k) \propto k\) spectrum. Asymptotically, \(E(k) \propto k\) for the whole range of \(k\), thus indicating thermalization. These results are akin to those of Euler turbulence despite complex collisions and interactions among the particles.