Clustering and Velocity Distributions in Granular Gases Cooling by Solid Friction

Abstract

We present large-scale molecular dynamics simulations to study the free evolution of granular gases. Initially, the density of particles is homogeneous and the velocity follows a Maxwell-Boltzmann (MB) distribution. The system cools down due to solid friction between the granular particles. The density remains homogeneous, and the velocity distribution remains MB at early times, while the kinetic energy of the system decays with time. However, fluctuations in the density and velocity fields grow, and the system evolves via formation of clusters in the density field and the local ordering of velocity field, consistent with the onset of plug flow. This is accompanied by a transition of the velocity distribution function from MB to non-MB behaviour. We used equal-time correlation functions and structure factors of the density and velocity fields to study the morphology of clustering. From the correlation functions, we obtain the cluster size, $L$, as a function of time, $t$. We show that it exhibits power law growth with $L(t)\sim t^{1/3}$

arXiv comment13 pages, 8 figures

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• Granular Fluids with Solid Friction and Heating
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• Intruder Dynamics in a Frictional Granular Fluid: A Molecular Dynamics Study
• Velocity Distribution and Diffusion of an Athermal Inertial Run-and-Tumble Particle in a Shear-Thinning Medium
• Enskog kinetic theory of binary granular suspensions: heat flux and stability analysis of the homogeneous steady state
• Virial Equation of State for a Granular System