Speaker:
Alessandro d’Amico (Case Western University)
Title: How Third-order Loops Bridge Different Length Scales and Collapse Multidimensionality without Compromising Predictive Capabilities in Dense Suspensions.
Authors:
A. D’Amico (Case Western Reserve University), K. Rajasekar (Case Western Reserve University), I. Davies (Case Western Reserve University), R. Pappalardo (Case Western Reserve University), S. Tu (Case Western Reserve University), and A. Singh (Case Western Reserve University)
Abstract:
The viscosity of dense suspensions increases under external deformation, a phenomenon known as shear thickening.The shear thickening of dense suspensions under stress results from a system dominated by lubricated interactions transitioning to a system dominated by frictional contacts. This talk focuses on relating the frictional contact network to macroscopic rheological phenomena for both continuous and discontinuous shear thickening (CST and DST). At low stress, the frictional force network is strongly anisotropic, creating frictional force chains along the compression axis. As stress increases, so does isotropy and small-order cycles propagate through the system. Three-node cycles, referred to as third-order loops, are shown to be key to predict the changes in viscosity. A strong correlation emerges between the number of edges belonging to third-order loops and the suspension’s viscosity. Notably, this correlation holds true independently of stress, volume fraction, and coefficient of friction, underlining the importance of the mesoscale frictional contact network in governing macroscopic rheology. The talk will end with a discussion about how to extend these ideas to three-dimensional suspensions.