Modelling the flow-induced anisotropy of the mechanical response of concentrated suspensions

Suspensions, which exhibit complex behaviors such as shear thickening, thinning, and jamming, are prevalent in nature and industry. However, predicting the mechanical properties of concentrated suspensions, and especially transient ones, remains a significant challenge, impacting product quality and process efficiency. In this study, we focus on developing a robust theoretical framework to explain how flow history governs the anisotropy of mechanical responses in suspensions of hard particles under unsteady flow conditions. Our starting point is the Gillissen-Wilson constitutive model [1], which we confront to DEM simulation data of the micro-structure and stress responses during steady shear, shear reversal, and shear rotations [2-3], where the shear axis is rotated by a specific angle. We use our measurements of the distinct contributions of hydrodynamic forces and particle contacts to the stress response to inform improvements to the Gillissen-Wilson model.