Regensburg 2019 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 32: Complex Fluids and Soft Matter (joint session DY/CPP)

DY 32.7: Talk

Wednesday, April 3, 2019, 16:45–17:00, H3

Re-entrant) Splashing of drops impacting on a heated plate at reduced pressure — •Kirsten Harth, Michiel van Limbeek, Paul Hoefnagels, and Detlef Lohse — Physics of Fluids, Max Planck Center and Universiteit Twente, Enschede, The Netherlands

Splashing drops capture our minds with their fascinating beauty - and splash control is highly relevant in a wide range of applications involving impacting drops. It is thus not surprising that diverse criteria for the splash threshold have been put forward over the last decades, with a recent breakthrough by Riboux and Gordillo (e.g. PRL 113 189901 (2014)). The effect of the surrounding gas is included via the mean free path, thus the theory also captures the disappearance of upon decrease of the ambient pressure. In our present understanding, identical drops remain intact at low impact velocities, while they always splash above a critical velocity.

Drop impact on heated surfaces in reduced pressure, however, bears a counterintuitive surprise: At temperatures below the static Leidenfrost point TL, the transition from deposition to splash is followed by another disappearance of splashing, before it reappears at larger impact velocity in a wide range of parameters. Above TL, splashing occurs at tremendously reduced impact velocity. We analyse this peculiar behaviour using different high speed imaging techniques.