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Competing Timescales Lead to Oscillations in Shear-Thickening Suspensions
J A Richards1, J R Royer1, B Liebchen1,2
1SUPA, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom.
Physical Review Letters
|August 7, 2019
Summary
Researchers discovered that the interplay between instrument inertia and particle contact formation in shear-thickening suspensions causes unique oscillations. This finding provides new insights into suspension dynamics and particle contact relaxation times.
Area of Science:
- Rheology
- Soft Matter Physics
- Materials Science
Background:
- Shear-thickening suspensions exhibit complex flow behaviors.
- Understanding the dynamics of interparticle contacts is crucial for predicting suspension properties.
Purpose of the Study:
- To investigate the emergence of novel dynamics in shear-thickening suspensions.
- To explore the role of competing timescales in generating these dynamics.
- To quantify particle contact relaxation times.
Main Methods:
- Experimental rheometry with controlled instrument inertia.
- Modeling the coupling between instrument timescales and interparticle contact formation.
- Analysis of shear-rate oscillations.
Main Results:
- A coupling between instrument inertia and frictional contact formation leads to asymmetric shear-rate oscillations.
- Experimental variations in timescales confirm the model's predictions.
- Oscillations provide access to the shear-jamming regime of the flow curve.
- Oscillation frequency quantifies intrinsic particle contact relaxation time.
Conclusions:
- The coupling of timescales is a key mechanism for novelty in dense suspension flow.
- Instrument inertia serves as a model system for studying these generic dynamics.
- This work opens new avenues for characterizing particle contact dynamics in complex fluids.
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