Eggs and milk: Spinning spheres partially immersed in a liquid bath

Abstract

When a hard-boiled egg spins through a pool of milk on the kitchen counter, the milk rises up the sides of the egg and droplets are ejected. This phenomenon occurs when any partially submerged object whose radius increases upward from the fluid surface (e.g., spheres, inverted cones, and rings) spins in a liquid bath. The fluid ejects from the surface near the maximum radius in one of three ejection modes: jets, sheets, or sheet breakup. Additionally, a surprisingly large flow rate is induced by the spinning object. In this study, we used spheres to determine the effects of experimental parameters on the induced flow rate. We characterized the modes of ejection and measured the sheet breakup distance using high-speed imaging. The basis of our closed form analytical model utilizes an integral momentum boundary layer analysis both beneath the free surface and in the thin film attached to the sphere. We present criteria defining the transitions between ejection modes and the radius where liquid sheets break up in the sheet ejection regime. Criteria defining the transitions between ejection modes and the radius where liquid sheets break up in the sheet ejection regime shows good agreement with experiments.

Rotary atomization of Newtonian and viscoelastic liquids

“…(1)-( 3) in their study of the rotary atomization for Newtonian liquids (a more recent study has been performed by Truscott and coworkers [24]). In their studies they found that by increasing either the rotation rate of the cup, or the flow rate of the supplied fluid, three separate regimes 033601-5 emerge and they represented these regimes in a dimensionless parameter space corresponding to the values of two closely related dimensionless product groups 1 = ω ρD 3 /σ = √ 8We and…”

“…By varying the flow rate and the centripetal acceleration, researchers have observed several different regimes of fragmentation for Newtonian liquids [20][21][22]. There have been several attempts at quantifying the transition criteria separating these different regimes [20,21,23,24]. Also, several semiempirical correlations have been suggested for the variation in average droplet size with rotation rate, feed rate and fluid properties [11,21,[25][26][27].…”

Egg-speriments: Stretch, crack, and spin

“…For example, the rise of a hard-boiled egg from horizontal to vertical when spun sufficiently rapidly on a table allows to discuss concepts of solids mechanics 8,9 . Also, an egg spinning through a pool of milk on the kitchen counter and inducing milk rise and droplet ejection constitutes a nice exama) Electronic mail: yann.bertho@universite-paris-saclay.fr ple of fluid mechanics and capillary phenomenon 10 . Among the possible experiments that can be realized with an egg, some of them involve the complex fluids contained inside the eggshell.…”