| Wed November 28th 2012 15:00 ZH286 | Seminar | Effect of the substrate on the morphology of droplet impact Anne-Laure Biance |
Details:he classical problem of droplet impact on a solid substrate is investigated. During an impact, the droplet is deformed and takes the shape of a liquid sheet surrounded by a thick rim.In the first part, we focus on the role of surface topology on the impact characteristics. As a model configuration, we study the impact of Leidenfrost droplet on a smooth substrate with one well defined single defect. We show that in specific conditions, the lamella is ruptured on the defect location. We rationalise these observations by scaling laws [1]. Then the role of solid/liquid friction on a smooth substrate is investigated. We go beyond classical observations and we use an absorption method associated to high speed PIV to track the droplet profile and the flow field within the lamella. These new experimental data allow us to investigate the role of solid/liquid friction on the impact morphology. To achieve this goal, we perform impact on a cold substrate in a total wetting situation and compare it to low friction impact on a plate heated above the Leidenfrost temperature. The results obtained are in very good agreement with recent theoretical and numerical results [2,3], showing that the lamella thickness is limited by the development of a viscous boundary layer from the substrate. This boundary layer is suppressed in the low friction configuration. These new results allow us to model the entire impact dynamics and in particular to predict quantitatively the maximal diameter reached by the droplets in different model situations. Collaborators: H. Lastakowski, C. Pirat, C. Ybert [1]A.-L. Biance, C. Pirat, C. Ybert Physics Of Fluids, vol. 23, p. 022104 (2011) [2] I. V. Roisman, E. Berberovic, and C. Tropea. Physics Of Fluids, 21, 2009. [3] J. Eggers, Fontelos M. A., Josserand C., and S. Zaleski. Drop dynamics after impact on a solid wall: Theory and simulations. Physics Of Fluids, 22:062101, 2010. | ||
