  Experimental investigations were carried out to elucidate the role of surface
wettability and inclination on the post impact dynamics of droplets. Maximum
spreading diameter and spreading time were found to decrease with increasing
inclination angle and normal Weber number for superhydrophobic surfaces. The
experiments on SH surfaces were found to be in excellent agreement with an
existing analytical model, incorporated with the modifications for the oblique
impact conditions. Energy ratios and elongation factor were also measured for
different inclination angles. On inclined SH surfaces, different features like
arrest of secondary droplet formation, reduced pinch off at the contact line
and inclination dependent elongation mechanism were observed. Contrary to SH
surfaces, hydrophilic surfaces show opposite trends of maximum spreading factor
and spreading time with inclination angle and normal Weber number respectively.
This was due to the dominance of tangential kinetic energy over adhesion energy
and gravitational potential at higher inclination angles. Finally, colloidal
solutions of nanoparticles were used to elucidate slip and disjoining pressure
on SH and hydrophilic surfaces, respectively. Overall, the article provides a
comprehensive picture of post impact dynamics of droplets on inclined surfaces
encompassing a broad spectrum of governing parameters like Reynolds number,
Weber number, degree of inclination and surface wettability.
