(369b) Simulations of Transient Dynamics of Dense Suspensions

Shear thickening of dense suspensions has been intensively studied due to its importance in many industrial applications. However, less is known about the transient phenomena such as impact activated solidification or dynamic shear jamming. Here we rely on LAMMPS-based discrete particle simulations to understand the dynamics of particulate suspensions, which are comprised of bi-disperse non-Brownian spherical particles at high volume fraction. Near-field hydrodynamic forces, short-range repulsions and frictional forces are considered in our model. As the volume fraction increases, we observe a transition from continuous shear thickening (CST) to discontinuous shear thickening (DST), which is consistent with experimental observations. We then apply our simulation tool to study dynamic shear jamming of dense suspensions in a quasi-one dimensional system. The particles are confined by two solid boundaries (top and bottom) that are sufficiently separated, and periodic boundary conditions are applied in the other directions. At the beginning of the simulation both boundaries are stationary, and then suddenly the bottom boundary starts to move with a constant speed. As the boundary moves, we observe a propagating front that moves with a constant speed, and the measured front speed is consistent with that reported in a recent experiment. We further investigate how the frictional force and the short-range inter-particle force determine the formation of the jamming front and its velocity. Our simulations provide detailed structures of the suspension at transient state, and are therefore helpful for elucidating the transient dynamics of dense suspensions.