Clustering of Granular Assemblies with Temperature Dependent Restitution under Keplerian Differential Rotation

The clustering of granular assemblies is studied under the influences of (i) a temperature-dependent coefficient of restitution and in (ii) a central gravitational force field. Our stability analyses of the constitutive equations as well as numerical experiments show that in case (i) clusters are still formed even though collisions become more elastic as the temperature decreases. In case (ii) the clusters appear as a transient phenomenon during the establishment of a quasiequilibrium. These transient patterns rotate driven by the shear and then they ``melt'' away with elapsed time.