Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 61: Granular Matter / Contact Dynamics (joint session DY/CPP)
DY 61.9: Vortrag
Donnerstag, 15. März 2018, 12:15–12:30, BH-N 333
Rheology of Dense Granular Fluids: Theory & Experiment — •Till Kranz1,2, Olfa Lopez1, Annette Zippelius3, Matthias Fuchs4, and Matthias Sperl1,2 — 1Institut für Materialphysik im Weltraum, DLR Köln — 2Institut für Theoretische Physik, Uni Köln — 3Institut für Theoretische Physik, Uni Göttingen — 4Theorie der Weichen Materie, Uni Konstanz
Granular fluids have been found to display a complicated rheology including Newtonian, shear thinning as well as shear thickening regimes. For a continuum description of granular flows, a constitutive equation is required that captures high densities and high shear rates.
We will introduce simple arguments regarding the time and energy scales in the system to explain the different flow behaviors. Newtonian rheology is expected at the lowest densities and shear rates only, shear thinning is related to the granular glass transition [1], and Bagnold scaling [2] is a consequence of hard-core interactions and shear heating. We will show how these constraints can be made quantitative in the framework of Granular ITT (Integration Through Transients) [3]. We will present experimental results for the flow behavior measured in a fluidized bed Couette cell that are well described by our theoretical approach.
[1] W. T. Kranz, M. Sperl and A. Zippelius, Phys. Rev. Lett. 104,
225701 (2010)
[2] R. A. Bagnold, Proc. Royal Soc. A 225, 49 (1954)
[3] W. T. Kranz, F. Frahsa, A. Zippelius, M. Fuchs and M. Sperl,
arXiv:1710.04452, arXiv:1710.04475