Deformation and Coalescence of Two Impacting Droplets in Microgravity

The collision of two water droplets between one and two milliliters in a microgravity environment is investigated. Practical droplet coalescence research has a modest sample size, although many papers have theorized how droplet collisions may act in microgravity environments. These collisions directly impact fluid mixing in microgravity, liquid sprays, and microfluidics focusing on droplet fusion. This research is conducted through the utilization of the Dryden Drop Tower located at Portland State University. The colliding and merged droplet(s) trajectories are extracted from high-speed video captured during each drop tower test and are used to calculate the individual and merged Webber number(s). Dye is used to visualize the mixing of the two droplet volumes. The dependence of the morphology of the post-collision droplet on the size and velocity of the colliding droplets is discussed.