Penetration and ligament formation of viscoelastic droplets impacting on the superhydrophobic mesh

Spraying occurs by the impact of water droplets on the superhydrophobic wire meshes by liquid penetration during the spreading and recoiling. We have shown that adding a small amount of high molecular weight polymer (PEO) alters the ligaments formation and stabilizes them due to its high elasticity. Consequently, it suppresses droplet spray during droplet spreading and recoiling (recoil penetration). In the wide range of the impact velocities, the penetrated ligaments retracted back to the mesh after reaching the maximum length and eventually merged with the droplet on the mesh. The empirical fitting shows that the ligament evolution follows the parallel spring-dashpot model of Kelvin-Voigt. The additive polymer also changes the recoil penetration mechanisms from cavity collapse to cavity detachment due to the higher retraction velocity of the cavity near the mesh that is induced by the upward flow formed by the retraction of the ligaments to the mother droplet. A model based on mass conservation is proposed to calculate the variation of the maximum ligament size.

Automated summary

The addition of high molecular weight polymer stabilizes droplets on superhydrophobic wire meshes, suppressing their spray behavior. Penetrated ligaments retract and merge with droplets on the mesh, and their evolution follows the Kelvin-Voigt model. The additive polymer also alters the recoil penetration mechanism.