Crown breakup by a thousand holes
Kinki University, Higashi-Osaka 571-8502, Japan
The high-speed video clips show the breakup of an impact crown, by the formation of Marangoni driven holes. The Marangoni stresses arise from gradients in surface tension along the free surface. The impacting viscous drop is 5 mm in diameter consisting of an 89% glycerin-water mixture. It is released from a height of 4.37 m and impacts at 7.7 m/s onto a glass plate, which has been wetted with a 35 m thick layer of ethanol. The surface tension of the ethanol spray is much smaller than that of the crown liquid, producing the Marangoni stresses when these droplets hit the crown. The time duration from the first contact of the drop until full breakup of the sheet is only about 3 ms.
In the third clip, taken at 100000 fps, the fine spray of ethanol droplets is pulled down into the crown, where the droplets hit the upper level of the sheet and start puncturing the holes. The numbers in the lower right-hand corner of the video frames show the time in µs. Reference 1 contains more details on the ultrahigh-speed video camera.
1T. G. Etoh, D. Poggemann, G. Kreider et a1., “An image sensor which captures 100 consecutive frames at 1000000 frames/s,” IEEE Trans. Electron Devices 50, 144 (2003).