Numerical study of air entrapment in yield-stress viscous droplets under impact onto a solid surface

Numerical study of non-Newtonian fluid droplets impacting onto dry solid surfaces has been carried out. Yield-stress viscous droplets were applied. Detailed numerical observations of droplet impact dynamics with the focus of air entrapment were obtained. Comparison of air entrapment between Newtonian and non-Newtonian droplets has been made. Simulation results showed that for non-Newtonian droplets with shear thinning behaviours the created air disc and air bubbles during droplet spreading are reduced tremendously in comparison to Newtonian viscous droplets because of the quite low liquid viscosity. The effects of droplet properties, impact velocity and static contact angles on the maximum air disc and on the air bubble release from the film were analysed.