Self-Propulsion of Boiling Droplets on Thin Heated Oil Films

We report on the self-propulsion of boiling droplets which, despite their contact with viscous, immiscible oil films, attain high velocities comparable to those levitating Leidenfrost droplets. Experiments and model reveal that droplet propulsion originates from a coupling between seemingly disparate short long timescale phenomena due microsecond fluctuations induced by events at droplet-oil interface. This interplay leads continuous asymmetric vapor release momentum transfer for velocities.Received 13 January 2021Revised 25 May 2021Accepted 29 June 2021DOI:https://doi.org/10.1103/PhysRevLett.127.074502© 2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCapillary interactionsDrop & bubble phenomenaEvaporationHeat transferLubricantsSurface tension effectsThin fluid filmsWettingPhysical SystemsMultiphase flowsPolymers Soft MatterFluid Dynamics