title: Droplet-air collision dynamics: evolution of the film thickness.
abstract: This study is devoted to the experimental and theoretical investigation of aerodynamic drop breakup phenomena. We show that the phenomena of drop impact onto a rigid wall, drop binary collisions, and aerodynamic drop deformation are similar if the correct scaling is applied. Then we use observations of the deforming drop to estimate the evolution of the film thickness of the bag, the value that determines the size of the fine child drops produced by bag breakup. This prediction of film thickness, based on film kinematics, is validated for the initial stage by direct drop thickness measurements and at the latest stage by the data obtained from the velocity of hole expansion in the film. It is shown that the film thickness correlates well with the dimensionless position of the bag apex.
authors.affiliation: Institute of Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Petersenstraße 17, 64287 Darmstadt, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Opfer
authors.affiliation: Institute of Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Petersenstraße 17, 64287 Darmstadt, Germany.
authors.forename: I V
authors.initials: IV
authors.lastname: Roisman
authors.affiliation: Evonik Industries AG, Goldschmidtstraße 100, 45127 Essen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Venzmer
authors.affiliation: Evonik Industries AG, Goldschmidtstraße 100, 45127 Essen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Klostermann
authors.affiliation: Institute of Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Petersenstraße 17, 64287 Darmstadt, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Tropea