title: Rheological chaos of frictional grains.
abstract: A two-dimensional dense fluid of frictional grains is shown to exhibit time-chaotic, spatially heterogeneous flow in a range of stress values, σ, chosen in the unstable region of s-shaped flow curves. Stress-controlled simulations reveal a phase diagram with reentrant stationary flow for small and large stress σ. In between, no steady flow state can be reached, instead the system either jams or displays time-dependent heterogeneous strain rates γ(r,t). The results of simulations are in agreement with the stability analysis of a simple hydrodynamic model, coupling stress and microstructure which we tentatively associate with the frictional contact network.
authors.affiliation: Institute of Theoretical Physics, Georg-August University of Göttingen, 37073 Göttingen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Grob
authors.affiliation: Institute of Theoretical Physics, Georg-August University of Göttingen, 37073 Göttingen, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Zippelius
authors.affiliation: Institute of Theoretical Physics, Georg-August University of Göttingen, 37073 Göttingen, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Heussinger