Steady quasi-homogeneous granular gas state

Using Newtonian molecular dynamics we study a gas of inelastic hard disks subject to shear between two planar parallel thermal walls. The system behaves like a Couette flow and it is tuned to produce a steady state that ideally has uniform temperature, uniform density, no energy flux and a linear velocity profile for restitution coefficient in the wide range: 0.3⩽r⩽1. It is shown that Navier–Stokes-like hydrodynamics fails far from the quasielastic regime. The system shows significant non-Newtonian behavior as non linear viscosity, shear thinning and normal stress differences. Our theoretical description of this state, based on generalized hydrodynamic equations derived from a moment expansion of Boltzmann's equation, agrees reasonably well with the simulational results, and captures the non-Newtonian features of the system. We claim that our hydrodynamic equations constitute a general formalism appropriate for describing different regimes of granular gases.