Non-Newtonian granular hydrodynamics. What do the inelastic simple shear flow and the elastic Fourier flow have in common?

TL;DR

This paper explores a special class of steady Couette flows in dilute granular gases with non-Newtonian hydrodynamics, unifying Fourier and shear flows, and confirms findings through simulations and analytical methods.

Contribution

It identifies a class of flows where viscous heating balances inelastic cooling, linking granular and ordinary gas flows under a unified framework.

Findings

Viscous heating balances inelastic cooling in certain steady flows.

Rheological functions match those in uniform shear flow.

Simulation and analytical results confirm the theoretical description.

Abstract

We describe a special class of steady Couette flows in dilute granular gases admitting a non-Newtonian hydrodynamic description for strong dissipation. The class occurs when viscous heating exactly balances inelastic cooling, resulting in a uniform heat flux. It includes the Fourier flow of ordinary gases and the simple or uniform shear flow (USF) of granular gases as special cases. The rheological functions have the same values as in the USF and generalized thermal conductivity coefficients can be identified. These points are confirmed by molecular dynamics simulations, Monte Carlo simulations of the Boltzmann equation, and analytical results from Grad's 13-moment method.