Mr Pitikaris investigated the local mechanical properties of static and dynamic granular systems under supervision of Prof. Dr. Matthias Sperl in the group Granular Media. In a driven granular fluid local perturbations where induced by means of active microrheology. The nonlinear response of the system was analysed and three separate shear rate dependent regimes could be identified.
In a static packing of stress-birefringent disks the internal stress fields of bidisperse systems could be investigated. On local scale, heterogeneities in mechanical quantities such as the bulk or shear modulus were detected.
The level of heterogenity was attributed to the compression state of the packing as well as the geometrical structure.
Finally, the cooling behaviour of granular gases of ellipsoidal particles in microgravity was investigated. Haff's law could be confirmed which predicts the decline in the average velocity of particles in granular gases.