The symmetry in asymmetric post-impact behaviors of droplets impacting on the inclined and moving surfaces

The asymmetric post-impact behaviors of droplets impacting on the inclined or moving surface are ubiquitous, which is important to various corresponding applications in biology, sustainability, and engineering. This asymmetry arises from the synergy between normal and tangential momentum with respect to the inclination or surface velocity, which is generally investigated in previous research separately. The present paper experimentally and theoretically demonstrates that the post-impact behaviors on the inclined or moving surface can be integrated into a universal system. Redefining the characteristic velocity ΔV, the morphology, spreading and height coefficient, and contact time of the droplet have been proved. Finally, the scaling laws of previous studies for the maximum spreading coefficient and the increment of the translational velocity are extended into a generalized frame, both feasible to inclined and moving surfaces. The work enhances comprehension and offers guidelines for more effective manipulation of the asymmetric post-impact behaviors exhibited by droplets upon impact.