On the high impact collision between two droplets

By means of a cutting technique developed recently, we have found new regimes of binary droplet collision at high Weber number, We, and identified the transition boundaries for various break-up mechanisms that shed light on the fundamental structure of droplet dynamics and further application to industrial purposes. Specifically, when We is increased beyond the range generally reported in the literature whereby separation with satellite droplets are observed, fingering structure is generated, which inhibits appearance of disintegration via the normal pinching mechanism for separation because of increased viscous dissipation. The latter structure will again be formed when We becomes sufficiently large. With further increase of We, the fingers are disrupted, leading to shattering of multiple droplets out of the circumference. The radius where the breaking occurs increases first with We and then decreases, leading to a critical We whence secondary droplets are emitted outward immediately after the impact. Copyright © 2009 by K. L. Pan.