Figure 2.

(a) Schematic drawing of droplet contacting substrate. The impact velocity is u₀, the front expanding velocity is v_l, and the thickness of the liquid film front is h. The expanding front is highlighted with red dashed lines, and (b) shows a magnified schematic of the expanding front. Key differences caused by the presence of nanoparticles are represented by yellow spheres and labels. The nanoparticle volume fraction, ranging from dilute to more concentrated, are indicated via a color gradient (light to dark, respectively). The viscous boundary layer and droplet breakup tip marked are additionally marked in red dashed lines.