Droplet bouncing and jump-off forces on ridged substrates
Phys. Rev. Fluids 10, 093604 – Published 25 September, 2025
DOI: https://doi.org/10.1103/cz2d-3vsd
Abstract
It seems to be common sense that decreasing the pore size of a mesh surface, thereby enhancing the capillary pressure resisting the liquid penetration, is the only way to suppress its penetration. Here, we demonstrate that a macro-ridge created on a mesh surface increases its dynamic pressure threshold for liquid penetration by a droplet by up to 130%. This phenomenon is attributed to the symmetry and synchronicity breaking of the flow-focusing process during the retraction stage of droplets. Based on multiple flow-focusing events of separate liquid films at different sites that take place synchronically and independently, experiments and analyses are conducted to capture the timescale, magnitude, and the resultant pressure of the droplet jump-off force imparted onto ridged substrates, despite the variations in droplet impact speed, liquid viscosity, and the ridge morphology.
