Dr. Matthias Sperl

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The dynamics in granular matter is inherently out-of-equilibrium, as
time-reversal symmetry is broken by the energy loss during interparticle
collisions. This presents challenges to both theory and experiment:
Experimentally, granular systems need to be agitated strongly to achieve
steady states or need to be measured in microgravity to avoid sedimentation.
For the theoretical treatment, suitable ensembles need to be assumed or
inferred from experiments.

Experiments from parabolic-flight and drop-tower campaigns shall be shown for
the dilute regime of granular gases where homogeneous steady states and
granular cooling are observed. For dense granular fluids, the derivation of
granular rheology from first principles shall be presented as well as new
experimental techniques for the characterization of granular states such as
X-ray radiography and tomography, and terahertz scattering.

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DLR Cologne
Seminarraum Theoretische Physik
Contact: Joachim Krug