Drop Impact on Hot Surfaces

• Applicant: Dr. Kirsten Harth
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2017 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 394307351

• Final Report Year: 2020

Final Report Abstract

Droplet dynamics was experimentally investigated in different configurations, with focus on impact on hot plates at ambient and reduced pressure. TIR was extended to investigate the solidification in direct vicinity of the substrate during spreading and impact on cold surfaces. Experimental methods were mainly high-speed shadowgraphy, frustrated total internal reflection (in Twente) and synchrotron X-ray imaging (at Argonne Ntnl. Lab, USA). Beyond hot substrates, investigations of solidification processes in spreading drops on cold substrates and coalescence processes were investigated. New methods were learnt and developed. In particular, the unforeseen highspeed X-ray measurements still contain a multitude of insights. The development of micro-electronic surface temperature sensors and investigations of impact on oily / deformable surfaces shall be continued in follow-up research.

Publications

• From Bouncing to Floating: The Leidenfrost Effect with Hydrogel Spheres, Phys. Rev. Lett., 121, 048001 (2018)
  S. Waitukaitis, K. Harth, M. van Hecke
  (See online at https://doi.org/10.1103/PhysRevLett.121.048001)
• Drop Impact on Hot Plates: Contact times, Lift-off and the Lamella Rupture (2020)
  S. H. Lee, K. Harth, M. Rump, M. Kim, D. Lohse, K. Fezzaa, J. H. Je
  (See online at https://doi.org/10.1039/d0sm00459f)
• Fast-freezing kinetics inside a droplet impacting on a cold surface, Proc. Ntnl. Acad. Sci. USA, 117, 2788 (2020)
  P. Kant, R. B. J. Koldeweij, K. Harth, M. A. J. van Limbeek, D. Lohse
  (See online at https://doi.org/10.1073/pnas.1912406117)