Droplet impact dynamics on pillared surfaces are critical for applications in inkjet printing, 3D printing, heat transfer, and surface engineering. This study numerically investigates the dynamic behavior of a shear-thinning droplet impacted on a cylindrical pillar of different diameters for impact Weber numbers ranging from 25 to 100. The droplet exhibits bottom rebound on a flat surface. However, the impact of a droplet on a vertical cylindrical pillar led to its splitting into two portions: a satellite droplet and a remaining volume that either slides along the surface of the pillar or breaks into multiple secondary droplets, depending on the impact conditions. The satellite droplet shows a bottom rebound on the top surface of the pillar, and its size has increased with an increase in pillar to droplet diameter ratio (dp/do). The impact force of the droplet on the pillar shows the highest value near the impact point, and then diminishes for pillared substrates and shows a second peak on a flat substrate. The magnitude of peak force has increased with an increase in dp/do and is highest in the absence of a pillar. The energy budget of the droplet reveals that the rate of dissipation of its initial energy is highest for the flat surface, and the presence of a pillar has slowed the rate of dissipation of energy.
Patel et al. (2026) studied this question.