Granular gases with elongated particles on an air table

IPR, Univ Rennes, CNRS UMR 6251, Campus Beaulieu, Rennes, F-35042, Bretagne, France

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Published online: 1 December 2025

Abstract

We investigate pseudo two-dimensional homogeneous granular gases made of elliptical particles on an air table. The air flow both suspends the particles and provides them translational and rotational energy. An equilibrium is achieved when the energy provided by the air flow is balanced by the dissipation accompanying movement and collisions of particles. We characterised the steady states for different aspect ratios and surface fractions. These steady states remain uniform and isotropic in the range of mvestigated parameters. Interestingly, we found that the translational temperature T decreases with increasing aspect ratio. In contrast, the in-plane rotational temperature Θ increases monotonously with aspect ratio up to 2 but then abruptly decreases for an aspect ratio of 3. Lastly, the temperature ratio Θ/T is independent of the surface coverage and increases with increasing aspect ratio; it seems to saturate to 0.25. These findings provide new insights into shape-dependent collision dynamics and energy dissipation in granular systems.