Noncoalescence of Drops - dancing water on water
Drops of water sometimes bounce off a pool of water instead of coalescing. Fluid dynamicists have been fascinated by this behavior since the 1800s, but it was Couder et al. who explained that these droplets can bounce indefinitely as long as the thin air layer separating the drop and pool is refreshed by vibrating the pool.
In this video, Destin from SmarterEveryDay teams up with astronaut Don Pettit to film the phenomenon in beautiful high-speed.
Watch: The WALKING WATER Mystery (in SPACE and SLOW MOTION!) - Smarter Every Day 160 - YouTube
It turns out that the cello produces just the right frequencies to create a cascade of bouncing water droplets.
And since Destin mentions the equation of Collisional Kinetic Energy (CKE), I have to mention that a perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision.
Paper:
From Bouncing to Floating: Noncoalescence of Drops on a Fluid Bath
When a drop of a viscous fluid is deposited on a bath of the same fluid, it is shown that its coalescence with this substrate is inhibited if the system oscillates vertically. Small drops lift off... // www.researchgate.net
h/t FYFD
fyfluiddynamics
Celebrating the physics of all that flows. See Fuck Yeah Fluid Dynamics for more. Please note that, unless otherwise indicated, uploaded video... // www.youtube.com
Для опыта нужны два вида бусин (они будут разные по плотности), дистиллированная вода, соль и изопропиловый спирт.
Внизу в бутылке соляной раствор, вверху изопропанол.
Так как солевой раствор плотнее, чем изопропиловый спирт, он опустится на дно, а изопропиловый спирт будет сверху. При встряхивании бутылки жидкости смешиваются и образуют временную эмульсию, плотность которой меньше плотности бусин синего цвета, поэтому они погружаются на дно.
И наоборот — плотность эмульсии больше плотности белых бусин, поэтому они плавают наверху. Когда эмульсия разделяется обратно на две жидкости, всё возвращается на исходную.