Acoustically Levitated Liquid Droplet

Acoustic levitation can be used as a sample holding device to facilitate containment and a contamination-free environment for X-ray characterization. A stable levitation of liquid droplets can be achieved on the nodes of standing sound waves via equilibrium of competing forces of gravity, drag, with acoustic radiation. Visual observations indicate that the levitating liquid droplets are experiencing jitter in all three directions. Jittering in levitating droplets has shown a higher rate of evaporation compared to stable ones. To understand the phenomena involved in the evaporation process of acoustically levitated droplets, finite element analysis simulations were performed. The simulation results were compared with particle imaging velocimetry (PIV) to validate the modeling effort. The simulation and solvent evaporation-rate measurements show that the evaporation rate is higher for solvents with higher vapor pressures, lower viscosities, and lower compressibility factor. This presentation will cover acoustic levitation, its application at the Advanced Photon Source at Argonne, and simulation efforts to understand the physics behind acoustic levitation.