Collision dynamics of high-speed droplets upon layers of variable thickness
Resource
Experiments in Fluids 45 (3): 435-446
Journal
Experiments in Fluids
Journal Volume
45
Journal Issue
3
Pages
435-446
Date Issued
2008
Date
2008
Author(s)
Pan, K. L.
Cheng, K. R.
Chou, P. C.
Wang, C. H.
Abstract
The collision dynamics between a droplet and a film has been studied with high-impact energy that can be grouped in a dimensionless Weber number, We, as normalized by surface energy. To accomplish this, we have developed a technique based on cutting of a high-speed jet, which can generate a single droplet with speed up to 23 m/s and We on the order of thousands. It was found that the boundaries indicating the occurrence of a central jet and that of a secondary droplet disintegrated from the jet decreased monotonically with increased dimensionless film thickness, H, and remained constant when the film thickness was larger than the crater depth. However, the transition designating multiple droplets that are originated from a central jet shows a non-monotonic trend with the variation of H, with a minimum We being at H ≈ 3, which is about the maximum crater depth, owing to a tuning behavior. The critical We for splashing that occurs at an early phase immediately after the impact is relatively sensitive to the film thickness only when H is between 1 and 2, which increases with reduced H. At large We (≳2,570 for high H), the ejected crown is closed to form a bubble and the transition boundary reveals a similar dependence on H as that for creation of a central jet. © 2008 Springer-Verlag.
SDGs
Other Subjects
Drops; Dynamics; Fluid mechanics; Jets; Magnetic films; Speed; Surface chemistry; Surface tension; Collision dynamics; Crater depth; Film-thickness; High speeds; High-speed jets; Impact energies; Monotonically; Non-monotonic; Remained constant; Secondary droplets; Single droplet; Speed ups; Surface energies; Transition boundaries; Variable thickness; Weber number; Drop formation
Type
journal article
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