Impinging hollow droplet of glycerin in spray coating influence of mutable obstacle and dynamic contact angle

In this study, droplet impact on a solid surface with obstacles occurring in many technological processes was numerically analyzed. The simulation of the hollow droplet impact on to solid surface used the volume of fluid method. A hollow droplet consists of a liquid shell enclosing an air cavity. The hollow droplet impact onto the surface has an obstacle with a different ratio of D/h and diameter of obstacle at three different speeds. It is found that the obstacle made dual jet in some cases. The length of the counter jet decreased with increased the dimension of the obstacle that the maximum and minimum length of the jet is been in case 1 at impact velocity 10 m s−1 and case 3 in V = 5 m s−1. Spread factor (f) increased 34.61% and 44.31% when impact velocity changed 1 m s−1–5 m s−1 and 10 m s−1 respectively.