As a droplet impacts on a granular substrate, both the intruder and the target deform, during which the liquid may penetrate into the substrate. {These three aspects together distinguish} it from other impact phenomena in the literature. We perform h
igh-speed, double-laser profilometry measurements and disentangle the dynamics into three aspects: the deformation of the substrate during the impact, the maximum spreading diameter of the droplet, and the penetration of the liquid into the substrate. By systematically varying the impact speed and the packing fraction of the substrate, (i) the substrate deformation indicates a critical packing fraction $phi^*approx 0.585$; (ii) the maximum droplet spreading diameter is found to scale with a Weber number corrected by the substrate deformation; and (iii) a model about the liquid penetration is established and is used to explain the observed crater morphology transition.
We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction $phi_{rm avg}$ ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of $phi_{rm avg}$ and anti-correla
tions for $phi_{rm avg}>0.8277$. The spatial extent of the anti-correlation increases with $phi_{rm avg}$ while the position of the maximum of the anti-correlation and the extent of the positive correlation shrink with $phi_{rm avg}$. We conjecture that the onset of anti-correlation corresponds to dilatancy onset in this system.
