Simulating droplet impact on a substrate of arbitrary shape

We have developed a three-dimensional model of free surface flows that can accommodate the presence of arbitrary-shaped obstacles in the flow. The model is an extension of one developed earlier by Bussmann, Mostaghimi, and Chandra [1]. To validate the model we simulated the impact of a 2-mm-diameter water droplet landing with low velocity (similar to1 m/s) on tubes ranging in diameter from 0.5 to 6.35 mm. Computer-generated images of droplet deformation after impact agreed well with photographs. Droplets landing on the largest tube (6.35-mm diameter) clung to the solid surface following impact. On smaller tubes there was not enough surface area for the liquid to remain attached, and droplets fell off after impact, disintegrating into several smaller droplets as they fell. The number of droplets produced after breakup was sensitive to the location of the impact point on the tube surface.