Impact of viscoelastic polymer solution droplets on a granular bed

The impact of polymer solution droplets on granular beds is relevant to powder processing, binder-jetting additive manufacturing, and environmental applications involving erosion control or spray deposition, yet most controlled studies of drop-grain interactions have focused on Newtonian liquids. In this study, we experimentally investigate the impact of viscoelastic polyethylene oxide (PEO) solution droplets on a dry granular bed and compare the resulting cratering dynamics with those of Newtonian liquids over a wide range of impact energies and Ohnesorge numbers. Crater morphology changes with impact energy, and this evolution occurs at lower energies for drops of polymer solution, consistent with their distinct liquid-grain interactions during impact. The crater diameter exhibits two distinct regimes: a low-energy plateau and a power-law increase at higher impact energies. We identify the transition between these regimes and show that, although the plateau size and the power-law scaling remain nearly unchanged, viscoelastic droplets reach the transition at a lower impact energy than Newtonian droplets. This suggests that the non-Newtonian response introduced by PEO modifies how the impact energy is partitioned among droplet deformation, liquid-grain coupling, and dissipation in the granular bed.