Jupiter, known for its colorful bands of stormy clouds, is a beautiful subject for fluid dynamics in action. As the planet turns, the cloud bands move at different relative speeds. This velocity difference at the interface of the bands can trigger the Kelvin-Helmholtz instability, resulting in a line of whorls where the cloud bands meet. The instability has been observed on Saturn and is thought to be fairly common among gas giants.
Tag: instability
Benard Cells
When a fluid in a gravitational field is heated from below, it can develop a Rayleigh-Benard instability which causes the formation of convection cells as in the video above. The hexagonal shape of the cells is due to the boundary conditions of the fluid. It’s possible to form other shapes like spirals. The same mechanism drives the formation of granules on the photospheres of stars like our sun.
Breaking up in Crossflow
This video shows some instabilities that occur when a liquid jet impinges on a flowing cross stream. Note how the jet breaks down into droplets in a fashion similar to the Plateau-Rayleigh instability but the broken tip remains stable for some time thereafter. #
Whipping Instabilities
When jets of liquid are introduced into an electrified medium in a process known as electrospinning, they can exhibit behavior known as whipping instabilities.
Dripping into Droplets
The Plateau-Rayleigh instability is one that just about everyone has witnessed. It describes how a liquid jet breaks up into droplets. Notice the waviness in the jet before breakdown. The tiniest curvature in the jet causes an imbalance in the liquid’s pressure due to surface tension. Because the system is unstable, any small changes will become larger, ultimately resulting in the jet breaking into droplets.
