Kaye effect
The Kaye effect is a property of complex liquids which was first described by the British engineer Alan Kaye in 1963.[1]
While pouring one viscous mixture of an organic liquid onto a surface, the surface suddenly spouted an upcoming jet of liquid which merged with the downgoing one.
This phenomenon has since been discovered to be common in many non-Newtonian liquids (liquids with a shear stress dependent viscosity or viscoelastic properties). Common household liquids in this category are liquid hand soaps, shampoos and non-drip paint. The effect usually goes unnoticed, however, because it seldom lasts more than about 300 milliseconds. The effect can be sustained by pouring the liquid onto a slanted surface, preventing the outgoing jet from intersecting the downward one (which tends to end the effect).
Whilst it was long thought to occur due to a shear-thinning slip layer,[2] recent studies have shown through high-speed videos[3] and experiments in a vacuum chamber[4] that an extremely thin layer of air (approximately 1000 times thinner than the jet diameter) is entrained, which acts as a lubricant and supports the sliding jet.
The current theory is that viscoelasticity is key. In a jet viscoelastic fluid, a portion of the energy of deformation as the jet falls is recoverable, and this reduces the force required to support the leaping jet, enabling more air to be entrained.[4]
References
- ^ Kaye, A. (1963). "A Bouncing Liquid Stream". Nature. 197 (4871): 1001–1002. Bibcode:1963Natur.197.1001K. doi:10.1038/1971001a0. S2CID 4265638.
- ^ Versluis, M; Blom, C; et al. (2006). "Leaping shampoo and the stable Kaye effect". Journal of Statistical Mechanics: Theory and Experiment. 2006 (7): P07007. arXiv:physics/0603183. doi:10.1088/1742-5468/2006/07/P07007. S2CID 119096147.
- ^ Lee, S; Li, E; et al. (2013). "Leaping shampoo glides on a lubricating air layer". Physical Review E. 87 (6): 061001. Bibcode:2013PhRvE..87f1001L. doi:10.1103/PhysRevE.87.061001. hdl:1969.1/185287. PMID 23848618.
- ^ a b King, J; Lind, S (2019). "The Kaye effect: New experiments and a mechanistic explanation". Journal of Non-Newtonian Fluid Mechanics. 273: 104165. doi:10.1016/j.jnnfm.2019.104165.
External links
- Bizarre liquid jets explained - the Kaye effect
- Puzzle of Leaping Liquid Solved.
- The Kaye effect using shampoo.
- The Kaye effect shot through a high speed camera.
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