Impaction of a droplet on an orifice plate

A novel method of generating secondary droplets using the impaction of a liquid droplet on an orifice plate is proposed. Here, a numerical simulation of this problem is provided using a one fluid volume-of-fluid-based method without considering air in the environment. The impacting droplet may partly spread on the surface of the plate, and partly penetrate through the orifice. The penetrated part may breakup forming a daughter droplet, as well as smaller satellite droplets. The sizes of the generated droplets are related to the volume of the liquid immediately on top of the orifice upon impact. The outcome of the impaction is discussed based on the sizes of the daughter and satellite droplet formed, their velocities, the breakup time, and the breakup length of the penetrated ligament. The influence of the following parameters on the outcome of the impaction is considered: liquid viscosity, liquid surface tension, initial droplet size and velocity, orifice diameter, and the liquid contact angle. A critical Re-c number exists for any given We number, under which droplet generation is impossible. Generally, the size of the generated droplet is weakly influenced by the liquid viscosity, and strongly influenced by the liquid surface tension. The size of the daughter droplet increases with the orifice size and reduces with the liquid viscosity, whereas the size of the satellite droplet increases with the viscosity. (C) 2004 American Institute of Physics.