(256c) Using Network Theory Insights into Flow and Dynamics of Dense Suspension Rheology: Node- and Edge-Centric Methods

Dense suspensions of neutrally buoyant particles, at high packing fraction, φ display high non-intuitive non-newtonian flow properties, such shear-thickening or shear jamming^1,2. Recent simulations have been successful in quantitatively reproducing experiments through Lubrication-Friction Discrete Element Method (LF-DEM) models where particles interact via hydrodynamic lubrication forces and frictional contact forces^3,4,5. This picture is still mean-field and the collective motion of particles and in depth study of mesoscale contact and force network that is continuously formed and destroyed under shear is still poorly understood. Here we use network theory to provide insights into detailed mesoscale features using two dimensional simulations of shear thickening suspensions. An edge centric approach to network theory indicates that at low stresses, when the network is not fully developed the third order loop edges are the major contributing factors in describing the strong shear thickening behavior. Additionally, a node centric approach reveals that as networks fully develop, the average angle between nodes decreases. Our results highlight the critical importance of mesoscale collective motion and rearrangements, thus providing a new way to understand the flow behavior of dense suspensions.

References:

1. Morris, J. F. Shear Thickening of Concentrated Suspensions: Recent Developments and Relation to Other Phenomena. Annu. Rev. Fluid Mech. 52, 121–144 (2020).
2. Singh, A. Hidden hierarchy in the rheology of dense suspensions. MRS Comm. 13(6), 971-979 (2023).
3. Singh A., Mari R., Denn M.M., Morris J.F. A constitutive model for simple shear of dense frictional suspensions. J. Rheol. 62, 457–468 (2018).
4. Singh, A., Jackson, G. L., van der Naald, M., de Pablo, J. J. & Jaeger, H. M. Stress-activated Constraints in Dense Suspension Rheology. ArXiv210809860 Cond-Mat (2021).
5. Singh, A., Ness, C., Seto, R., de Pablo, J. J. & Jaeger, H. M. Shear Thickening and Jamming of Dense Suspensions: The “Roll” of Friction. Phys. Rev. Lett. 124, 248005 (2020).