title: From splashing to bouncing: The influence of viscosity on the impact of suspension droplets on a solid surface.
abstract: We experimentally investigated the splashing of dense suspension droplets impacting a solid surface, extending prior work to the regime where the viscosity of the suspending liquid becomes a significant parameter. The overall behavior can be described by a combination of two trends. The first one is that the splashing becomes favored when the kinetic energy of individual particles at the surface of a droplet overcomes the confinement produced by surface tension. This is expressed by a particle-based Weber number We_{p}. The second is that splashing is suppressed by increasing the viscosity of the solvent. This is expressed by the Stokes number St, which influences the effective coefficient of restitution of colliding particles. We developed a phase diagram where the splashing onset is delineated as a function of both We_{p} and St. A surprising result occurs at very small Stokes number, where not only splashing is suppressed but also plastic deformation of the droplet. This leads to a situation where droplets can bounce back after impact, an observation we are able to reproduce using discrete particle numerical simulations that take into account viscous interaction between particles and elastic energy.
authors.affiliation: James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Klein Schaarsberg
authors.affiliation: James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.|Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
authors.forename: Ivo R
authors.initials: IR
authors.lastname: Peters
authors.affiliation: James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Menachem
authors.initials: M
authors.lastname: Stern
authors.affiliation: James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Dodge
authors.affiliation: James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Zhang
authors.affiliation: James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Heinrich M
authors.initials: HM
authors.lastname: Jaeger