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Unsteady flow, clusters, and bands in a model shear-thickening fluid
Shibu Saw1, Matthias Grob1, Annette Zippelius1
1Institute for Theoretical Physics, Georg-August University of Göttingen, Friedrich-Hund Platz 1, 37077 Göttingen, Germany.
Physical Review. E
|February 20, 2020
Summary
Granular materials exhibit large-scale instabilities and shear thickening below jamming. Flow dynamics reveal distinct patterns like force chains and clusters, depending on strain rate.
Area of Science:
- Physics
- Materials Science
- Fluid Dynamics
Background:
- Granular materials are complex systems exhibiting unique flow behaviors.
- Understanding jamming and shear thickening is crucial for predicting material response.
Purpose of the Study:
- To analyze flow curves and large-scale instabilities in 2D granular assemblies.
- To investigate the influence of strain rate on flow patterns and dynamics.
Main Methods:
- Simulation of 2D granular particle assemblies with frictional contact forces.
- Analysis of flow curves, stress, and strain rates.
- Observation of large-scale patterns and their dynamics.
Main Results:
- Identified a large-scale instability below jamming, creating a range of non-stationary flow.
- Observed continuous shear thickening in large systems due to heterogeneous flow averaging.
- Discovered strain-rate dependent patterns: force chain bands and large-scale clusters.
Conclusions:
- Granular flow below jamming is characterized by instabilities and complex emergent patterns.
- System-spanning patterns emerge with infinite correlation length, similar to impact experiments.
- Strain rate dictates the type and propagation direction of observed flow structures.
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