AUTHOR=Thirisangu Jeyapradhap , Subramani Karthick TITLE=Sorting droplets beyond the Rayleigh limit under acoustic-gravity forces: a theoretical approach JOURNAL=Frontiers in Acoustics VOLUME=Volume 3 - 2025 YEAR=2025 URL=https://www.frontiersin.org/journals/acoustics/articles/10.3389/facou.2025.1544464 DOI=10.3389/facou.2025.1544464 ISSN=2813-8082 ABSTRACT=The physics of droplets beyond the Rayleigh limit offers a novel acoustic sorting method that is fundamentally different from the techniques applied to sort droplets within the Rayleigh limit. Using this “acoustic sorting beyond Rayleigh limit” method, we theoretically demonstrate that by controlling the frequency (f) and acoustic energy density (Eac), smaller droplets can be suspended while larger ones settle against gravity, or larger droplets can be suspended while smaller ones settle. Intriguingly, this method also enables the suspension of intermediate-sized droplets, allowing both smaller and larger droplets to settle simultaneously. Furthermore, acoustic sorting is demonstrated for droplets of identical size but with varying interfacial tensions.