Deformation upon impact of a concentrated suspension drop
arXiv:2003.10798 · doi:10.1017/jfm.2020.394
Abstract
We study the impact between a plate and a drop of non-colloidal solid particles suspended in a Newtonian liquid, with a specific attention to the case when the particle volume fraction, , is close to - or even exceeds - the critical volume fraction, , at which the steady effective viscosity of the suspension diverges. We use a specific concentration protocol together with an accurate determination of for each drop and we measure the deformation for different liquid viscosities, impact velocities and particle sizes. At low volume fractions, is found to follow closely an effective Newtonian behavior, which we determine by documenting the low deformation limit for a highly viscous Newtonian drop and characterizing the effective shear viscosity of our suspensions. By contrast, whereas the effective Newtonian approach predicts that vanishes at , a finite deformation is observed for . This finite deformation remains controlled by the suspending liquid viscosity and increases with increasing particle size, which suggests that the dilatancy of the particle phase is a key factor of the dissipation process close to and above .
Submitted to JFM