Granular Fluids

Prof. Dr. Annette Zippelius

Universität Göttingen

Granular particles in agitated motion appear in numerous applications in nature
and technology, and are also of fundamental interest in nonequilibrium statisti-
cal physics. The dynamical evolution of granular fluids is governed by inelastic
collisions leading to a continuous dissipation of energy. In contrast to molecular
fluids equipartition of energy therefore does not hold, the spatially homogeneous state is unstable, velocities do not obey the Maxwell-Boltzmann-distribution, and translational and rotational degrees of freedom are correlated.
The focus of the talk is on cohesive granular particles. We shall first discuss
structure formation in dilute systems, where particles aggregate in a self-similar
process which is analysed with event-driven simulations and scaling arguments.
We then go on to discuss a dense, freely falling stream of granular particles. As in a molecular fluid the stream is generacilly unstable to the formation of droplets, which is shown with help of a continuum theory and simulations.