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Discontinuous shear thickening: fluid dynamics or granular physics?

Ryohei Seto (Levich Institute, CCNY), Romain Mari (Levich Institute / CCNY), Jeffrey Morris (Levich Institute and Dept. of Chemical Engineering, CCNY), Morton Denn (Levich Institute and Dept. of Chemical Engineering, City College of New York)

Complex Fluids: Suspensions, Emulsions, and Gels

Tue 10:45 - 12:15

Barus-Holley 160

We introduce a simulation model to capture abrupt shear thickening of non-Brownian concentrated suspensions. In a hydrodynamically interacting vanishing Reynolds number suspension, it is known that interactions from closely approaching particles, so-called lubrication force, dominate the dynamics. In this work, unlike other works with lubrication force models, we allow particles to come into contact, assuming that there is some breakdown in the lubrication singularity. We are specifically interested in the interaction of contact forces and hydrodynamic interactions, considering particles which are nearly hard spheres. In the contact model, we also take into account frictional forces, which resist tangential displacements between contacting particles. The combination of lubrication forces and a frictional contact model reproduces shear-rate dependence of the viscosity of concentrated suspensions, exhibiting either mild or abrupt shear thickening depending upon the particle volume fraction and friction coefficient. The results of the simulation allow us to expose the dynamics, microstructure and correlations associated with the onset of shear thickening of various types, and in particular to explore the role of frictional contacts in setting these behaviors.