Dyed milk pulls away after a drop of acetone is added. The acetone creates a gradient in the surface tension, which causes mass flow due to the Marangoni effect. See a video of the effect (or try it yourself at home!) here.
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Flying Paint
High speed footage of flying paint demonstrates a world of viscosity and surface tension, as well as another great example of fluid dynamics as art. (via Gizmodo)
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DIY Solutal Convection
In this video, the HouseholdHacker heads to the kitchen and uses milk, food coloring, and dish soap to create some solutal convection much like this one with cream and liqueur. The food coloring serves as a tracer for the fluid motion; it’s really the interaction of the milk and the dish soap that drives the motion. The dish soap lowers the surface tension of the milk, causing motion via the Marangoni effect. That motion redistributes some of the dish soap as well, causing further motion in the form of a surface tension instability. As with the cream and liqueur experiment, the fat in the milk is important; you won’t see much (if any) effect with fat free milk because its surface tension properties aren’t as dissimilar to dish soap. (via misterhonk.de)
Soap Bubble Shapes
The shapes of soap bubbles are determined by surface tension, which ensures the smallest surface area for a given contained volume. (#) Their iridescent colors are created by the interference and refraction of light waves passing through the nonuniform thickness of the bubble, as well as to the motion of the soap mixture itself.
Photo credit: found via fuckyeaheyegasms, originally from teacupofmoons
Microgravity Marangoni
Astronauts are preparing an experiment on the Marangoni effect, in which a variation in surface tension can cause mass flow, for flight aboard the International Space Station. The effect, also responsible for causing tears of wine, will benefit from study in microgravity because competing effects like gravity-induced sedimentation and buoyant convection will be negligible. Astronaut Ron Garan reports more on the upcoming experiment on the Fragile Oasis blog.
Crown Breakup
When a droplet falls into a pool of similar fluid, one often observes a crown-like impact effect. This student video shows high-speed footage of different fluids crowning and explores the effects of surface tension on crown breakup.
Superfluid Dripping
This high-speed video shows superfluid helium dripping and breaking up. Although superfluid has no viscosity, this does not prevent the Plateau-Rayleigh instability from breaking the helium into droplets once the mass of the liquid is too great for surface tension to contain.
Tears of Wine
Tears of wine are caused by the Marangoni effect, in which a gradient in surface tension causes mass flow. The water in the wine has a higher surface tension than the alcohol in the wine, causing the wine to be drawn away from regions of higher alcohol concentration. #
Microfluidics
The field of microfluidics–where fluids are constrained to the sub-millimeter scale–is increasingly important in fields like chemistry, molecular biology, and microtechnology. At the microscale, surface tension often has greater effects than in our everyday world. This video shows how adding small amounts of a polymer drastically changes droplet breakup.
Zero-G Water Bubbles
Astronaut Don Pettit narrates some of his experiments with air and water droplets in microgravity in this video. The lack of body forces and buoyancy in microgravity means that surface tension effects frequently dominate. Pettit’s demonstrations also involve some fun basic physics with bubble behaviors inside of water droplets. See more of Pettit’s Saturday Morning Science videos for additional microgravity fluid mechanics.
