Drop Impact on Porous Superhydrophobic Polymer Surfaces

Abstract

Water drop impacts are performed on porous-like superhydrophobic surfaces. We investigate the influence of the drop size and of the impact velocity on the event. The Cassie-Baxter/Wenzel transition is observed to be a function of the drop size, as well as the outcomes of the impact or deposition process, which can be deposition, rebound, sticking, or fragmentation. A quantitative analysis on the experimental conditions required to observe rebound is provided. Our analysis shows that the wettability hysteresis controls the limit between deposition and rebound events. This limit corresponds to a constant Weber number. A survey of literature results on impact over patterned superhydrophobic surfaces is provided as a comparison.

Contactless prompt tumbling rebound of drops from a sublimating slope

“…SM1 in [30] for details on superhydrophobic surface preparation and video 5 in the SM [30] showing viscous drop behavior). In addition, drop pinning may occur on textured superhydrophobic surfaces as a result of drop impalement at high impact speed [22,31,32]: Impalement is not an issue for sublimating surfaces.…”

Aerosol generation by raindrop impact on soil

“…Aerosols generated from droplets hitting porous media can have significant impact on industrial applications as well as the environment [22][23][24] . There are several methods to generate aerosols such as electrospray, ultrasound and sprays; however, most methods use external energy sources to generate aerosol droplets.…”

Physicochemical Characteristics and Droplet Impact Dynamics of Superhydrophobic Carbon Nanotube Arrays

“…This actually suggests that the critical Weber number where droplet pinning takes place may be much smaller than We=1.79. In the very low We regime, the pinning Weber number (We 0 ), 24 can be roughly approximated as following:…”