Numerical simulation of droplet impact on textured surfaces in a hybrid state

High Weber number drops are found to undergo a Cassie-to-Wenzel transition on hydrophobic textured surfaces. Previous studies with many-body dissipative particle dynamics (MDPD) method were based on an absolute Cassie state, with no splash. Hence, an MDPD method was developed in this paper, which could simulate drop splashes in a hybrid state. Millimeter-sized drops on hydrophobic substrates were simulated with different solid fraction, and results were compared to experimental results using high-speed photography. The numerical spread diameter, contact time, and splash amount are matched with experiments. Results showed that hydrophobic substrates with lower solid fraction possess better water repellency as compared to those with similar apparent contact angle. However, the influence of the microstructure on superhydropho-bic surfaces is much less than that on hydrophobic ones, and surfaces with lower solid fraction did not have better water repellency capabilities. It is believed that the MDPD method proposed in this study can effectively predict relationship between surface topography and water repellency of a material.