Physics of Fluids - Publications

Self-propulsion of inverse Leidenfrost drops on a cryogenic bath

Open Access
Proceedings of the National Academy of Sciences 116, 1174–1179 (2019)

Authors

	Anaïs Gauthier
	Christian Diddens
	Rémi Proville
	Detlef Lohse
	Devaraj van der Meer

BibTeΧ

@article {Gauthier1174,
	author = {Gauthier, Ana{\"\i}s and Diddens, Christian and Proville, R{\'e}mi and Lohse, Detlef and van der Meer, Devaraj},
	title = {Self-propulsion of inverse Leidenfrost drops on a cryogenic bath},
	volume = {116},
	number = {4},
	pages = {1174--1179},
	year = {2019},
	doi = {10.1073/pnas.1812288116},
	publisher = {National Academy of Sciences},
	abstract = {An inverse Leidenfrost state can happen when ambient-temperature drops are deposited on liquid nitrogen, as the bath evaporation generates a vapor film that maintains drops in levitation. Contrary to what is seen on solids, drops levitating on a cryogenic liquid exhibit counterintuitive dynamics: They are spontaneously self-propelled (and glide in straight lines) and keep levitating, even after cooling down to a temperature equal to that of the bath. This spontaneous self-propulsion in a cryogenic environment{\textemdash}that lasts for tens of minutes{\textemdash}can be seen as an efficient way to freeze and further transport biological materials (such as cells or proteins) or chemicals without contamination or risk of heat degradation.When deposited on a hot bath, volatile drops are observed to stay in levitation: the so-called Leidenfrost effect. Here, we discuss drop dynamics in an inverse Leidenfrost situation where room-temperature drops are deposited on a liquid-nitrogen pool and levitate on a vapor film generated by evaporation of the bath. In the seconds following deposition, we observe that the droplets start to glide on the bath along a straight path, only disrupted by elastic bouncing close to the edges of the container. Initially at rest, these self-propelled drops accelerate within a few seconds and reach velocities on the order of a few centimeters per second before slowing down on a longer time scale. They remain self-propelled as long as they are sitting on the bath, even after freezing and cooling down to liquid-nitrogen temperature. We experimentally investigate the parameters that affect liquid motion and propose a model, based on the experimentally and numerically observed (stable) symmetry breaking within the vapor film that supports the drop. When the film thickness and the cooling dynamics of the drops are also modeled, the variations of the drop velocities can be accurately reproduced.},
	issn = {0027-8424},
	URL = {https://www.pnas.org/content/116/4/1174},
	eprint = {https://www.pnas.org/content/116/4/1174.full.pdf},
	journal = {Proceedings of the National Academy of Sciences}
}