Tunable shear thickening in suspensions.
Shear thickening, an increase of viscosity with shear rate, is a ubiquitous phenomenon in suspended materials that has implications for broad technological applications. Controlling this thickening behavior remains a major challenge and has led to empirical strategies ranging from altering the particle surfaces and shape to modifying the solvent properties. However, none of these methods allows for tuning of flow properties during shear itself. Here, we demonstrate that by strategic imposition of a high-frequency and low-amplitude shear perturbation orthogonal to the primary shearing flow, we can largely eradicate shear thickening. The orthogonal shear effectively becomes a regulator for controlling thickening in the suspension, allowing the viscosity to be reduced by up to 2 decades on demand. In a separate setup, we show that such effects can be induced by simply agitating the sample transversely to the primary shear direction. Overall, the ability of in situ manipulation of shear thickening paves a route toward creating materials whose mechanical properties can be controlled.
Department of Physics, Cornell University, Ithaca, NY 14853; yl834@cornell.edu.
Neil Y C
NY
Lin
School of Engineering, University of Edinburgh, Edinburgh EH9 3JL, United Kingdom;
Christopher
C
Ness
Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge CB3 0WA, United Kingdom.
Michael E
ME
Cates
School of Engineering, University of Edinburgh, Edinburgh EH9 3JL, United Kingdom;
Jin
J
Sun
Department of Physics, Cornell University, Ithaca, NY 14853;
Itai
I
Cohen
colloidal suspensions; flow control; rheology; shear thickening