Impact of particle laden drops onto surfaces of various wettability

Understanding characteristics of the impact of complex drops (liquid and solid particles) onto substrates is important for many applications, e.g. for additive manufacturing. Complex drops (diameter $\approx$ 3.8 mm) were produced using polyethylene microspheres dispersed in deionized water. Drop impact was investigated on substrates with different wettability (contact angles $<$5$^{\circ}$ and 95$^{\circ}$) using high-speed cameras and image processing methods. By varying speed of the drops (1.7 to 3.7 m/s), diameter of the particles (200 and 500 $\mu$m) and particles volume fraction (0 to 35${\%}$), the influence of these variables on the impact dynamics of the drop and the distribution of particles after the impact was studied. For hydrophilic substrate, drops with 200 $\mu$m particles are arranged in a ring after the impact. For hydrophobic substrate, drops can split into several drops depending on drop velocity, size and volume fraction of particles. Also, the dynamics of drop spreading was elucidated.