Bubbles, viscosity, diffusion, capillary action, and ferrofluids all feature in the artistic experiments of Kim Pimmel. Be sure to check out his previous film featured here. (Video credit: Kim Pimmel)
Penguins, already fluid dynamicists by nature, have developed clever methods of increasing their speed to escape from the leopard seals that prey on them. In the clip above, notice from 1:55 onward as the penguins swim for the surface and leap onto the ice - they leave a trail of bubbles in their wake. The penguins are using supercavitation to decrease their drag. When the penguins first dive in to the water, they splay their feathers out in the air and then lock them closed in the water, trapping pockets of air beneath them. When the need for a burst of speed arises, the penguin shifts its feathers to release the air, coating most of its body in a layer of bubbles. Because the drag in air is much less than the drag in water, this enables the bird to achieve much higher speeds than they normally do when swimming.
(Source: dvice.com)
Sometimes bursting one bubble just leads to more bubbles. This high-speed video shows how popping a bubble sitting on a fluid surface can lead to a ring of daughter bubbles. When the surface of the bubble is ruptured, filaments of the liquid that made up the surface are drawn back toward the pool by surface tension, trapping small pockets of the air that had been inside the bubble. A dimple forms on the surface and rebounds as a jet that lacks the kinetic energy to eject droplets. Watch as the jet returns to the interface, and you will notice the tiny bubbles around it. At 56 ms, one of the daughter bubbles on the left bursts. See Nature for more. (Video credit: J. Bird et al)
There’s beauty even in something as simple as two immiscible fluids—oil and water—colliding. (Video credit: Shawn Knol)
A 9mm bullet impacts a falling jet of water. High-speed video reveals the formation of a shock wave inside the jet. Because this shock wave is confined inside the jet, it causes strong secondary cavitation—the bubble that seems to explode in front of the bullet.
High-speed video of a soap bubble being popped reveals the directionality of the process. Like a the rubber of a bursting balloon, the soap film rushes away from the point of rupture, disintegrating as the information about a sudden lack of surface tension is propagated across the remaining film surface. In this regard, it is much like what happens when you drop a slinky toy.
Here astronaut Don Pettit demonstrates the effects of rotation on a sphere of water in microgravity. Bubbles, being less dense than water, congregate in the middle of the sphere along its axis of rotation. Tea leaves, which are denser than the water, are thrown to the outside; this is the same concept used in a centrifuge for separating samples.
Take a look at the physics of a pint of Guinness, including the formation of foam, the circulation of bubbles, and the importance of nitrogen and surfactants. The Physics of Fluids paper the host refers to is available here. (And, yes, I will admit to debating the physics occurring in my pint glass while in a pub.) # (via Martin)
Droplet collisions captured instantaneously create beautiful fluid sculptures that, though common, are too fast for the human eye. Here a bubble was blown onto the surface of the fluid, then a droplet was released to fall into the center of the bubble, bursting it. As that droplet rebounded in a Worthington jet, a second droplet was released and impacted the jet, creating the umbrella-like shape in the center. See Liquid Droplet Art for more photos. (Photo credit: Corrie White and Igor Kliakhandler) #
This timelapse video shows the spreading of food coloring and a ferrofluid through soap suds surrounding a magnet. Capillary action, the same force that enables sap to flow up through a tree against gravity, helps draw the fluids through the interfaces between the soap bubbles without disturbing the suds. The magnet’s field provides a preferred direction for the ferrofluid flow. (via Gizmodo)
Celebrating the physics of all that flows. 
