Sometimes the similarity between fluid flow and granular flows is quite striking. This video shows a stream of sand falling down a tube and impacting a rod. (Note: the view Keep reading
Month: March 2025
Inside a Splash
When a droplet strikes a pool, a thin, fast-moving sheet of liquid expands outward from the region of contact. These ejecta sheets come in many forms depending on surface tension, Keep reading
Cavitation in a Bottle
This high-speed video shows the cavitation that occurs when a bottle of water is struck. The impact accelerates the bottle downward, generating localized vacuums between the glass and the liquid. Keep reading
Island Vortex Street
Von Karman vortex streets are a pattern of alternating vortices shed in the wake of a bluff body. They’re commonly associated with cylinders and can be demonstrated in simulation and Keep reading
Viscous Fingers
Viscous liquid placed between two plates forms a finger-like instability when the top plate is lifted. The photos above show the evolution of the instability for four initial cases (top Keep reading
Bursting a Bubble
Though seemingly instantaneous to the naked eye, the bursting of a soap bubble is fascinating when slowed down. Here it is at about 2200 frames per second. Initially, the bubble Keep reading
Instability
[original media no longer available] Many systems can exhibit unstable behaviors when perturbed. The classic example is a ball sitting on top of a hill; if you move the ball Keep reading
Balloons in the Car
Destin from Smarter Every Day has just made a video on one of my favorite fluids brain teasers: what happens to a helium balloon when you accelerate in a car? Keep reading
Rubens’ Table
Veritasium’s new video has an awesome demonstration featuring acoustics, standing waves, and combustion. It’s a two-dimensional take on the classic Rubens’ tube concept in which flammable gas is introduced into a Keep reading
Rebounding
A water droplet can rebound completely without spreading from a superhydrophobic surface. The photo above is a long exposure image showing the trajectory of such a droplet as it bounces. Keep reading