The Kaye effect is a phenomenon observed in some complex liquids which was first described by the British engineer Alan Kaye in 1963. 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 In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both Viscosity, viscous and Elasticity (physics), elastic characteristics when undergoing deformation (engineering), deformation. Viscous mate ...

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, recent studies have shown through high-speed videos and experiments in a

vacuum chamber A vacuum chamber is a rigid enclosure from which air and other gases are removed by a vacuum pump. This results in a low-pressure environment within the chamber, commonly referred to as a vacuum. A vacuum environment allows researchers to c ...

that an extremely thin layer of air (approximately 1000 times thinner than the jet diameter) is entrained, which acts as a

lubricant A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, ...

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.

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External links

Bizarre liquid jets explained – the Kaye effect

The Kaye effect using shampoo

{{fluiddynamics-stub 1963 in science Rheology