72th Annual Meeting of the APS Division of Fluid Dynamics (November 23, 2019 — November 26, 2019)

V0074: Internal Flows of Leidenfrost Droplet

Authors

• Meng Shi, King Abdullah University of Science and Technology (KAUST)
• Costas Grigoropoulos, Laser Thermal Lab, University of California Berkeley

DOI: https://doi.org/10.1103/APS.DFD.2019.GFM.V0074

The Leidenfrost phenomenon, wherein a droplet is levitated by its own vapor when placed on a superheated surface, was discovered in 1756 and has been developed into various applications. For instance, the Leidenfrost droplet was used as a “Leidenfrost reactor” to synthesize gold nanoparticles. However, the internal flows inside the Leidenfrost droplet remain unclear, which will limit the applications of the Leidenfrost phenomenon on the inner space of droplets. In this study, we utilized the laser-assisted particle image velocimetry (PIV) method to investigate the internal flows inside Leidenfrost droplets. A continuous wave green laser was employed as the excitation source irradiating fluorescent particles inside the Leidenfrost droplet. Through analysis of the particle trajectories in the pictures recorded by high-speed camera, the average local velocities of internal flows can be obtained. The results indicated that, the internal flows in the Leidenfrost droplet are complex and highly affected by the surface temperature.