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O. Petzschmann (University of Potsdam, Germany), M. Sremcevic (University of Belgrad, Yugoslavia), J. Schmidt, F. Spahn (University of Potsdam, Germany)
It is well known that the equilibrium state of a planetary ring is determined by a balance of viscous heating and collisional cooling. The ring material consists of granular particles, i.e. the inter-particle collisions are dissipative. Therefore, the knowledge of the transport coefficients of granular gases is of crucial interest for the understanding of the ring dynamics.
As a first step, we concentrate our work on a granular gas of smooth spheres of unique size and with a constant coefficient of restitution.
We investigate the transport coefficients of granular gases by using N-body simulations and compare the results with analytic expressions derived by Jenkins and Richman (1985) in the framework of kinetic theory.
We find a good agreement with the results of Jenkins and Richman that are restricted to nearly elastic collisions and purely Newtonian fluids. Using our simulations, we check the limitations of their theory.
Furthermore, we investigate a sheared granular gas with variable restitution, in order to get a more realistic expression for the viscosity of the material of a planetry ring.