Dresden 2014 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 22: Slow Dynamics in Glasses and Granular Matter I (Joint Focus Session with DY and CPP)

DF 22.2: Hauptvortrag

Donnerstag, 3. April 2014, 10:00–10:30, HÜL 186

Complex rheology at the jamming transition: shear thickening, shear thinning, shear banding — •Claus Heussinger — Institut für theoretische Physik, Universität Göttingen

The jamming paradigm aims at providing a unified view for the elastic and rheological properties of materials as different as foams, emulsions, suspensions or granular media. The usefulness of such a unifying concept hinges on the presence or absence of phenomena that are in some sense *universal*.

In this contribution, we discuss how certain features in the particle interactions affect the rheological properties of the material. First, we discuss the effect of frictional forces, and show how the jamming phase diagram has to be modified as compared to the frictionless scenario [1,2]. Essential findings are a discontinuous and hysteretic jamming transition, as well as a shear thickening regime where frictionless particles are generically shear thinning.

Secondly, we investigate the role of attractive interactions between the particles [3]. For weakly attractive systems a fragile solid develops which displays self-organization towards a minimal (isostatic) connectivity. Moreover, the measured flow curves have unstable regimes, which lead to persistent shearbanding. These features are rationalized by establishing a link between rheology and inter-particle connectivity, which also provides a minimal theoretical model to describe the flow curves.

[1] CH, PRE (2013). [2] M. Grob. CH, A. Zippelius, arXiv (2013). [3] E. Irani, P. Chaudhuri, CH, arXiv (2013).