Transients in pressure-imposed shearing of dense granular suspensions

Granular materials whether dry or immersed in fluid show dilation or compaction depending upon the initial conditions, solid fraction and normal stress. Here we probe the transient response of a dense granular suspension subjected to change of applied normal stress under simple shear. In this aim, normal-stress-imposed discrete element particle simulations are developed considering the contributions arising from the drag induced on the particles by fluid phase. These pressure-imposed simulations show transient behaviors of dense granular suspensions such as dilation or compaction before reaching a steady state following the µ( J ) rheology. Less expectedly, the transient behavior, in particular the height of the system as a function of applied strain, can also be described by assuming that the system follows the steady µ( J ) rheology at all times.