A computational model for spinning effects on post-collision velocities of bouncing droplets

The present study proposed a computational model for the spinning effects on the post-collision characteristics (particularly velocities) of the bouncing droplets. The modeling work is based on the computational discoveries by using the validated volume-of-fluid method to simulate droplet collisions with various collisional parameters. The physical foundation of the model is based on the fact that the interchange between the orbital angular momentum and the spin angular momentum plays an important role in determining the post-collision velocities. First, the conversion of the orbital angular momentum into its spinning counterpart varies nonmonotonically with the impact parameter of two nonspinning droplets. Second, the conversion of the spin angular momentum into its orbital counterpart is significant for the collision between two spinning droplets. Furthermore, this spin-to-orbital angular momentum conversion varies monotonically with the azimuthal angle and is approximately independent of the translational Weber number, the spinning Weber number, and the Ohnesorge number. These computational discoveries have been analyzed for their physical meaning and taken into account in the proposed model.