Kaye effect


The Kaye effect is a property of 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 all shear-thinning liquids. Common household liquids with this property 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.
It is thought to occur when the downgoing stream "slips" off the pile it is forming, and due to a thin layer of shear-thinned liquid acting as a lubricant, does not combine with the pile. When the slipping stream reaches a dimple in the pile, it will shoot off it like a ramp, creating the effect.