Session: 10.2.2 - Interfacial Phenomena and Flows II

Paper Number: 170179

170179 - Sweeping by Sessile Drop Coalescence 

Abstract: 

When liquid droplets coalesce upon contact with a solid surface, they move across both the wetted region and the exposed solid area. The extent of this sweeping motion plays a crucial role in the performance of various technologies, including self-cleaning surfaces, anti-frost coatings, water collection systems, and dropwise condensation mechanisms. In such applications, weakly wetting or non-wetting surfaces are preferred, as they enhance droplet mobility and improve overall functionality.

To investigate these effects, experiments were conducted using two sessile droplets of equal size at the moment of coalescence on Teflon and sanded Teflon with different grit values to assess variations in initial contact angles. High-speed cameras captured the coalescence process from both side and top views, providing comprehensive insights into droplet behavior. The side view allowed for precise measurement of initial drop sizes and contact angles, while the top view confirmed the initial axisymmetry of the droplets and enabled analysis of the projected swept area and extensions. The sweeping motion and spread of the merged droplet were quantitatively assessed using MATLAB, and the experimental results were compared with numerical simulations to further understand the underlying fluid dynamics and validate observed trends. It was found that the experiments and the numerical simulations were in excellent agreement with one another for all cases.

Presenting Author: Alireza Dalili Farmingdale State College at State University of New York

Presenting Author Biography: Alireza Dalili, Ph.D. is an Assistant Professor in the Mechanical Engineering Technology Department at State University of New York (SUNY) at Farmingdale. He holds a BASc and PhD from University of Toronto and conducted his postdoctoral work at Cornell University. His doctoral and postdoctoral research was sponsored by NSF, NASA, US Department of Energy, NSERC and General Motors.