Kaye effect

A falling stream of shampoo shows the 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. Bibcode:1963Natur.197.1001K. doi:10.1038/1971001a0.
^ Versluis, M; Blom, C; et al. (2006). "Leaping shampoo and the stable Kaye effect". Journal of Statistical Mechanics: Theory and Experiment. 2006 (07): P07007. arXiv:physics/0603183. doi:10.1088/1742-5468/2006/07/P07007.
^ Lee, S; Li, E; et al. (2013). "Leaping shampoo glides on a lubricating air layer". Physical Review E. 87 (6): 061001. doi:10.1103/PhysRevE.87.061001. hdl:1969.1/185287.
^ Jump up to: ^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[]

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[1] Kaye, A. (1963). "A Bouncing Liquid Stream". Nature. 197 (4871): 1001. Bibcode:1963Natur.197.1001K. doi:10.1038/1971001a0.

[2] Versluis, M; Blom, C; et al. (2006). "Leaping shampoo and the stable Kaye effect". Journal of Statistical Mechanics: Theory and Experiment. 2006 (07): P07007. arXiv:physics/0603183. doi:10.1088/1742-5468/2006/07/P07007.

[3] Lee, S; Li, E; et al. (2013). "Leaping shampoo glides on a lubricating air layer". Physical Review E. 87 (6): 061001. doi:10.1103/PhysRevE.87.061001. hdl:1969.1/185287.

[kinglind-4] Jump up to: ^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.

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