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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Polymer and Molecular Dynamics, Friction and Rheology

CPP 20.1: Hauptvortrag

Dienstag, 28. März 2023, 09:30–10:00, ZEU 255

Granular Matter Rheology -- fluid-/solid-like behavior and state-transitions — •Stefan Luding — University of Twente, NL

The dynamic and static behavior of particulate and granular matter (like sand, powder, suspended particles, often with a wide distribution of particle sizes) is of considerable interest in a wide range of industries and research disciplines. Special is that they can behave both solid-like and fluid-like, which is a challenge for both academia and industry. The related mechanisms/processes in particle systems are active at multiple scales (from nano-meters to meters), and explaining their multiple states, and transitions, will lead to a better understanding of natural disasters like avalanches or industrial problems like silo-failure.

To understand the fundamental micro-mechanics and -physics, one can use particle simulation methods. However, large-scale applications (due to their enormous particle numbers) have to be addressed by coarse-grained models or by continuum theory. For this, to derive constitutive rheology relations, so-called micro-macro transition methods are necessary, which translate particle positions, velocities and forces into density-, stress-, and strain-fields, which must be compatible with the balance equations for mass, momentum, and energy of continuum theory. Additional non-classical fields describe the micro-structure (fabric, force-chains) or the statistical fluctuations,before an universal granular rheology can be defined, involving state-transitions between the states, the so-called jamming/un-jamming transitions.