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arXiv · 1910.11274

Stress fluctuations and shear thickening in dense granular suspensions

Qin Xu·Abhinendra Singh·Heinrich M. Jaeger
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Abstract

We experimentally investigate the rheology and stress fluctuations of granules densely suspended in silicone oil. We find that both thickening strength and stress fluctuations significantly weaken with oil viscosity $η_0$. Comparison of our rheological results to the Wyart-Cates model for describing different dynamic jamming states suggests a transition from frictional contacts to lubrication interactions as $η_0$ increases. To clarify the contribution from viscous interactions to the rheology, we systematically measure stress fluctuations in various flow states. Reduction of stress fluctuations with $η_0$ indicates that a strong lubrication layer greatly inhibits force correlations among particles. Measuring stress fluctuations in the strong shear thickening regime, we observe a crossover from asymmetric Gamma to symmetric Gaussian distributions and associated with it a decrease of lateral (radial) correlation length $ξ$ with increasing shear rate.

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Qin Xu, Abhinendra Singh, Heinrich M. Jaeger. 2019-10-22. Stress fluctuations and shear thickening in dense granular suspensions. https://doi.org/10.1122/1.5133037

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