title: Leaping shampoo glides on a lubricating air layer.
abstract: When a stream of shampoo is fed onto a pool in one's hand, a jet can leap sideways or rebound from the liquid surface in an intriguing phenomenon known as the Kaye effect. Earlier studies have debated whether non-Newtonian effects are the underlying cause of this phenomenon, making the jet glide on top of a shear-thinning liquid layer, or whether an entrained air layer is responsible. Herein we show unambiguously that the jet slides on a lubricating air layer. We identify this layer by looking through the pool liquid and observing its rupture into fine bubbles. The resulting microbubble sizes suggest this air layer is of submicron thickness. This thickness estimate is also supported by the tangential deceleration of the jet during the rebounding.
authors.affiliation: Department of Mathematics, Texas A&M University, College Station, Texas 77843-3368, USA.
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.forename: E Q
authors.initials: EQ
authors.lastname: Li
authors.forename: J O
authors.initials: JO
authors.lastname: Marston
authors.forename: A
authors.initials: A
authors.lastname: Bonito
authors.forename: S T
authors.initials: ST
authors.lastname: Thoroddsen
mesh_terms: D000388:Air; D003198:Computer Simulation; D003902:Detergents / Q000737:chemistry*; D017276:Friction; D054327:Lubricants / Q000737:chemistry*; D008153:Lubrication / Q000379:methods*; D008956:Models, Chemical; D012212:Rheology / Q000379:methods*; D013499:Surface Properties; D014783:Viscosity
chemical_list: D003902:Detergents; D054327:Lubricants