Solutal Marangoni effect and chemical reactions on interfacial instability of droplet driven by surface acoustic waves

Aerosol droplets of micrometer and sub-micrometer sizes may be produced quickly using surface acoustic wave (SAW) atomization. This study theoretically investigates the influence of the solutal Marangoni effect and chemical reactions on the instability of SAW-driven droplets. By applying lubrication theory to the governing equations, a droplet evolution equation is formulated, which is influenced by parameters such as the acoustic capillary number E, solutal Marangoni number M, and Damköhler number Da. In addition, the droplet evolution process is numerically simulated using the method of lines. When the SAW-induced capillary waves on the droplet reach a critical amplitude, atomization is triggered. Increases of M and Da lead to decreases in the droplet height profile h(x, t) and increases in the characteristic length L. Moreover, droplet atomization may result from an increase in the number of wave peaks, which is brought on by increases in M and Da. It is noteworthy that M and Da can regulate the atomization of droplets. However, the initiation of droplet atomization is only dependent on E. As M, Da, and E increase, the rate at which aspect ratio ε diminishes accelerates and the duration of the transition phase contracts, thereby precipitating an earlier onset of the quasi-stable stage. Moreover, increases in M and Da result in a reduction in the final ε.