Abstract
A liquid drop impacting a smooth solid substrate splashes by emitting a thin liquid sheet from near the contact line of the spreading liquid. This sheet is lifted from the substrate and ultimately breaks apart. Surprisingly, the splash is caused by the ambient gas, whose properties dictate when and if the sheet is created. Here, I focus on two aspects of this process. Using high-speed imaging I find that the time of thin-sheet creation displays a different quantitative dependence on air pressure if the sheet is created during the early stages of spreading, rather than when the liquid has already spread to a large radius. This result sheds light on previously observed impact velocity regimes. Additionally, by measuring impacts of drops on surfaces comprised of both rough and smooth regions, I identify a new threshold velocity that limits the times at which the thin sheet can be created. This velocity determines the threshold pressure below which splashing is suppressed.
Highlights
The splash of a liquid drop on a dry smooth surface is caused by the ambient air [1]
Experiments have found that drops splash only above a certain gas pressure in a variety of systems [1, 2, 3, 4, 5], and have provided insight into the liquid and air dynamics during splashing [6, 7, 8, 9]
By considering the role of thin-sheet creation in splashing, I am able to shed light on two outstanding questions: why two impact velocity regimes of threshold pressure exist [6], and why splashing is suppressed at low pressures
Summary
The splash of a liquid drop on a dry smooth surface is caused by the ambient air [1]. At a time tsheet after impact, the advancing liquid abruptly begins to move over a layer of air approximately several microns thick [16] If the pressure is decreased below a threshold Psheet, the thin sheet is never created and the splash is suppressed. In the second half of this paper, I focus on how Psheet is determined in the high impact velocity regime It had previously been shown [5] that thin-sheet formation can be suppressed if a drop impacts a rough surface. The threshold pressure is the pressure below which both conditions cannot be simultaneously satisfied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
