Orientational correlation and velocity distributions in uniform shear flow of a dilute granular gas

Abstract

Using particle simulations of the uniform shear flow of a rough dilute granular gas, we show that the translational and rotational velocities are strongly correlated in direction, but there is no orientational correlation-induced singularity at perfectly smooth ($\beta=-1$) and rough ($\beta=1$) limits for elastic collisions ($e=1$); both the translational and rotational velocity distribution functions remain close to a Gaussian for these two limiting cases. Away from these two limits, the orientational as well as spatial velocity correlations are responsible for the emergence of non-Gaussian high velocity tails. The tails of both distribution functions follow stretched exponentials, with the exponents depending on normal ($e$) and tangential ($\beta$) restitution coefficients.