Validation of finite element analysis strategy to investigate acoustic levitation in a two-axis acoustic levitator

• Published in: Physics of fluids (1994) 2020-09, Vol.32 (9)
• Main Authors: Sracic, Michael W., Suthar, Kamlesh J.
• Format: Article
• Language: English
• Subjects: Acoustic levitation; Acoustic waves; Acoustics; Computational fluid dynamics; Computer simulation; Displacement; Dynamic stability; Elastic waves; Finite element method; Fluid dynamics; High speed cameras; Nodes (standing waves); Physics; Simulation; Sound pressure; Standing waves; Wave equations
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/5.0020026

A two-axis acoustic levitator can be used to generate a standing pressure wave capable of levitating solid and liquid particles at appropriate input conditions. This work proposes a simulation framework to investigate the two-axis levitation particle stability using a commercial, computational fluid dynamics software based on the harmonic solution to the acoustic wave equation. The simulation produced predictions of the standing wave that include a strong “+” shaped pattern of nodes and anti-nodes that are aligned with the levitator axes. To verify the simulation, a levitator was built and used to generate the standing wave. The field was probed with a microphone and a motorized-scanning system. After scaling the simulated pressure to the measured pressure, the magnitudes of the sound pressure level at corresponding high-pressure locations were different by no more than 5%. This is the first time a measurement of a two-axis levitator standing pressure wave has been presented and shown to verify simulations. As an additional verification, the authors consulted high speed camera measurements of a reference-levitator transducer, which was found to have a maximum peak-to-peak displacement of 50 ± 5 μm. The reference-levitator is known to levitate water at 160 dB. The system for this work was simulated to match the operation of the reference-levitator so that it produced sound pressure levels of 160 dB. This pressure was achieved when the transducer maximum peak-to-peak displacement was 50.8 µm. The agreement between the two levitators’ displacements provides good justification that the modeling approach presented here produces reliable results.