title: Dynamics of non-Newtonian droplets.
abstract: We study the impact and subsequent retraction dynamics of aqueous liquid droplets upon high-speed impact on hydrophobic surfaces. Often a spectacular "rebound" of the droplet can be observed: after the impact and expansion, the drop retracts rapidly, leading to ejection of part of the material from the surface. We show how non-Newtonian flow properties can be used to slow down the retraction sufficiently to completely inhibit rebound. The slowing down is due to non-Newtonian normal stresses generated near the moving contact line of the droplet. We provide a quantitative theory for the slowing down, and show that the non-Newtonian effects profoundly change the contact line dynamics.
authors.affiliation: Physique et Mécanique des Milieux Hétérogènes, PMMH, ESPCI, Paris 6, Paris 7, UMR CNRS 7636, 75231 Paris cedex 5, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Bartolo
authors.forename: Arezki
authors.initials: A
authors.lastname: Boudaoud
authors.forename: Grégoire
authors.initials: G
authors.lastname: Narcy
authors.forename: Daniel
authors.initials: D
authors.lastname: Bonn