Dense dispersed media engineering

The Accelerated Stokesian dynamics method has been extended to model hydrodynamic interactions in shear flows of clay-like platelets. Effective interactions between platelets have been modelled, including anisotropy due to the anisotropic charge distribution over the platelets, and charge renormalization due to ion condensation. We observed and discussed a shear-induced glass-to-crystal transition in suspensions of such platelets. Hydrodynamic torques first rotate platelets so they can reach a transient quasi-nematic disordered state. These orientational correlations permit to unlock translational degrees of freedom and the platelets then form strings aligned with the velocity direction and hexagonally packed in the gradient–vorticity plane. Under steady shear, platelet orientations are correlated but the system is not nematic. After flow cessation and relaxation in quiescent conditions, positional and orientational order are further improved as the platelet suspension experiences a transition to a nematic hexagonal crystal.