Influence of slippage on thermocapillary flow induced by a Gaussian temperature distribution on small-scale water droplets driven by surface acoustic waves

In the present work, we theoretically analyze the influence of thermocapillary flow on the atomization by surface acoustic waves (SAWs) of a sessile water droplet exposed to a high-frequency acoustic field and placed over a substrate with slippage at the wall. Thermocapillary flow is induced by imposing a Gaussian temperature profile along the free surface of the droplet. Such fluid flow in conjunction with the acoustically-driven capillary waves at the free surface prior to atomization under the influence of the slip phenomenon is analyzed by applying the lubrication theory to the flow field governing equations, leading to the derivation of an evolution equation written in terms of the acoustic capillary number, the Marangoni number, and the substrate slip coefficient. The numerical solution of the evolution equation has led us to propose the combined influence of thermocapillary and slip phenomena as a valuable means of assisting in the regulation of aerosol diameter in SAW atomization, capable of exerting a significant influence on the interfacial dynamics of droplets prior to atomization.