**DPS Meeting, Madison, October 1998**

*Session 17P. Rings I, II*

Contributed Poster Session, Tuesday, October 13, 1998, 4:15-5:20pm, Hall of Ideas
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## [17P.07] Measurements of transport coefficients of granular gases using computer simulations

*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.

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