  We report the dynamics of a droplet levitated in a single-axis acoustic
levitator. The deformation and atomization behavior of the droplet in the
acoustic field exhibits a myriad of complex phenomena, in sequences of steps.
These include the primary breakup of the droplet through stable levitation,
deformation, sheet formation, and equatorial atomization, followed by secondary
breakup which could be umbrella breakup, bag breakup, bubble breakup or
multistage breakup depending on the initial size of the droplet. The
visualization of the interfacial instabilities on the surface of the liquid
sheet using both side and top-view imaging is presented. The primary breakup of
the droplet precedes with a stable levitation of the droplet. The thinning of
the sheet is caused by the differential acceleration induced by the greater
pressure difference between the poles and the equator. As the sheet thickness
reduces to the order of a few microns, Faraday waves develop at the thinnest
region (preceding to rim) which causes the generation of tiny-sized droplets
perpendicular to the sheet. The corresponding, hole formation results in a
perforated sheet that causes the detachment of the annular rim which breaks due
to Rayleigh Plateau (RP) instability. The radial ligaments generated in the
sheet possibly due to Rayleigh Taylor (RT) instability break into droplets of
different sizes. The secondary breakup exhibits We dependency and includes
umbrella, bag, bubble, or multistage, ultimately resulting in complete
atomization of the droplets. Both the primary and the secondary breakup of the
droplet admit interfacial instabilities such as Faraday instability, Kelvin
Helmholtz (KH) instability, RT instability, and RP instability and are well
described with visual evidence.
