Droplet jumping induced by coalescence of a moving droplet and a static one: Effect of initial velocity

To explore the effect of initial velocity on the droplet jumping induced by coalescence of a moving droplet and a static one, we performed simulations using the volume of fluid method with a dynamic contact angle model, and validated the simulation results against our experiments. The results show that the initial velocity of the moving droplet accelerates the droplet deformation during jumping, resulting in a unique departure feature. Droplet departs at different stages under different initial velocities, and the droplet departure velocity in the vertical direction is approximately constant at the first stage and then increases after Reynolds number reaches a critical value. The horizontal departure velocity is proportional to the initial velocity with a ratio of 0.4. The initial velocity also affects the energy conversion during the droplet jumping greatly. This work shall bring new insights into the droplet jumping behavior and promote its application in related fields.