March 11, 2013
When I starting working in industrial research, more than thirty years ago, about one in five of my colleagues were tobacco smokers. Everyone of them was smart enough to know that smoking was harmful to their health, and every year the number of smokers was reduced. One year, there was a betting pool among a few smokers to determine who could refrain from smoking the longest. The winner got a little money, but he started smoking again shortly thereafter.
When I left the labs after thirty years, not a single person was a smoker. The health benefit was an obvious motivation, but numerous obstacles were imposed over the years. No smoking was allowed in any corporate building, and any outside smoking was not allowed within thirty feet of a building entrance. Perhaps it should have been thirty meters for the research buildings.
When I was younger, I would see a few skilled smokers blowing smoke rings. There were even television cartoons, so old that they were in black and white, showing a cartoon character blowing smoke rings. Nowadays, a smoke ring is an uncommon sight. Just as for coffee rings, there's a bit of physics behind smoke rings, more properly called vortex loops, since they exist in more media than smoke in air.[1-3] I wrote about coffee rings in a recent article (Coffee Ring Physics, February 11, 2013).
The movement of a vortex loop is real. It's not like a wave, the motion of which is only apparent. As can be seen in the example of a smoke ring, the entrapped particles in the vortex travel farther than if they were just in a cloud. This long distance movement is enabled by the rolling interface between the loop and the surrounding fluid, since a vortex loop is a tube of fluid, spinning on the tube axis. The movement is usually in the direction orthogonal to the plane of the loop.
Vortex loops interested William Thompson (Lord Kelvin) in the mid-nineteenth century as a way to explain atoms. He conjectured that atoms were knotted loops of the Aether, with the number and type of knot giving the elements their particular properties. The vortex loop atomic theory was wrong, but it inspired research on vortices. Hermann von Helmholtz published a mathematical analysis of vortex loops in 1858.
Although linked and knotted vortex loops have been described in theory since that time, they had never been created in the laboratory. Physicists from the University of Chicago have now developed a technique for generation of vortex loops, including knotted loops, in a water tank.[1-3] Their apparatus is quite ingenious, as the photographs, below, show. The loops are generated by the rapid movement of gas bubble coated airfoils in water.
The airfoils are created using a 3D printer, and they become coated with microbubbles of hydrogen and oxygen generated by the electrolysis of water. The 3D printing proved invaluable, since it took many iterations of airfoil shape to generate the desired vortices. When subjected to a 100 g acceleration, the bubbles detach from the airfoil and produce a propagating vortex loop, which is tracked with a high speed camera (see figure).
These experiments have yielded interesting results. Dustin Kleckner, a postdoctoral scientist at the James Franck Institute of the University of Chicago and coauthor of the vortex studies, notes that vortex knots, once thought to be persistent and stable, are not.
Says Kleckner, "They seem to break up in a particular way. They stretch themselves, which is a weird behavior." Their decomposition culminates in reconnection events in which parts of the vortices annihilate each other to produce unknotted loops from those that were originally knotted.
Knotted structures are thought to occur in turbulence, plasmas, fluids, both quantum and classical, and superfluids, but are nearly impossible to observe.[1-2] In many systems, the degree of knottedness has been thought to be a conserved quantity, and these experiments have shown that this might not always be the case.
These results are published online in Nature Physics in an article notable for its many freely-available supplementary videos. This research was funded by the Alfred P. Sloan Foundation, the Packard Foundation, and the National Science Foundation.
|Postdoc Dustin Kleckner holding a 3D-printed loop airfoil.|
(Still image from a YouTube Video by UChicago Creative/Robert Kozloff/University of Chicago.)
- Dustin Kleckner and William T. M. Irvine, "Creation and dynamics of knotted vortices," Nature Physics, Published Online March 3, 2013, doi:10.1038/nphys2560.
- Steve Koppes, "Vortex loops could untie knotty physics problems," University of Chicago Press Release, March 4, 2013.
- Daniel P. Lathrop and Barbara Brawn-Cinani, "News and Views - Fluid dynamics: Lord Kelvin's vortex rings," Nature Physics, Published Online March 3, 2013, doi:10.1038/nphys2577.
- H. von Helmholtz, "On Integrals of the hydrodynamical equations, which express vortex-motion," (1867 English Translation of original 1858 paper), Philosophical Magazine, Series 4 (1851–1875), vol. 33, no. 226.
Permanent Link to this article
Linked Keywords: Research and development; industrial research; tobacco smoking; tobacco smoker; health effects of tobacco; betting pool; laboratory; foot; meter; research; smoke ring; animated cartoon; television cartoon; black and white; cartoon character; coffee ring; physics; vortex loop; transmission medium; smoke; atmosphere of Earth; air; Adriaen Brouwer (1605-1638); Flemish; painter; alehouse; Rembrandt; Rubens; counterfeit; "Studies of Vortex Rings" by Andrien Guébhard; Wreaths of tobacco smoke; Wikimedia Commons; wave; cloud; rolling; interface; fluid; axis; orthogonal; plane; William Thompson (Lord Kelvin); nineteenth century; atom; conjecture; knot; Aether; chemical element; atomic properties; Hermann von Helmholtz; mathematics; mathematical; theory; physicist; University of Chicago; water; tank; gas; bubble; airfoil; electrolysis of water; electrolytic; microbubble; hydrogen; oxygen; YouTube Video; Dustin Kleckner; 3D printer; standard gravity; g; acceleration; high-speed photography; high speed camera; Robert Kozloff; experiment; postdoctoral research; scientist; James Franck Institute; annihilation; turbulence; plasma; fluid; quantum fluid; classical fluid; superfluid; conservation law; Nature Physics; video; Alfred P. Sloan Foundation; Packard Foundation; National Science Foundation; H. von Helmholtz, "On Integrals of the hydrodynamical equations, which express vortex-motion," (1867 English Translation of original 1858 paper), Philosophical Magazine, Series 4 (1851–1875), vol. 33, no. 226.
Latest Books by Dev Gualtieri
Thanks to Cory Doctorow of BoingBoing for his favorable review of Secret Codes!
Blog Article Directory on a Single Page
- Soybean Graphene - March 23, 2017
- Income Inequality and Geometrical Frustration - March 20, 2017
- Wireless Power - March 16, 2017
- Trilobite Sex - March 13, 2017
- Freezing, Outside-In - March 9, 2017
- Ammonia Synthesis - March 6, 2017
- High Altitude Radiation - March 2, 2017
- C.N. Yang - February 27, 2017
- VOC Detection with Nanocrystals - February 23, 2017
- Molecular Fountains - February 20, 2017
- Jet Lag - February 16, 2017
- Highly Flexible Conductors - February 13, 2017
- Graphene Friction - February 9, 2017
- Dynamic Range - February 6, 2017
- Robert Boyle's To-Do List for Science - February 2, 2017
- Nanowire Ink - January 30, 2017
- Random Triangles - January 26, 2017
- Torricelli's law - January 23, 2017
- Magnetic Memory - January 19, 2017
- Graphene Putty - January 16, 2017
- Seahorse Genome - January 12, 2017
- Infinite c - January 9, 2017
- 150 Years of Transatlantic Telegraphy - January 5, 2017
- Cold Work on the Nanoscale - January 2, 2017
- Holidays 2016 - December 22, 2016
- Ballistics - December 19, 2016
- Salted Frogs - December 15, 2016
- Negative Thermal Expansion - December 12, 2016
- Verbal Cues and Stereotypes - December 8, 2016
- Capacitance Sensing - December 5, 2016
- Gallium Nitride Tribology - December 1, 2016
- Lunar Origin - November 27, 2016
- Pumpkin Propagation - November 24, 2016
- Math Anxiety - November 21, 2016
- Borophene - November 17, 2016
- Forced Innovation - November 14, 2016
- Combating Glare - November 10, 2016
- Solar Tilt and Planet Nine - November 7, 2016
- The Proton Size Problem - November 3, 2016
- Coffee Acoustics and Espresso Foam - October 31, 2016
- SnIP - An Inorganic Double Helix - October 27, 2016
- Seymour Papert (1928-2016) - October 24, 2016
- Mapping the Milky Way - October 20, 2016
- Electromagnetic Shielding - October 17, 2016
- The Lunacy of the Cows - October 13, 2016
- Random Coprimes and Pi - October 10, 2016
- James Cronin (1931-2016) - October 6, 2016
- The Ubiquitous Helix - October 3, 2016
- The Five-Second Rule - September 29, 2016
- Resistor Networks - September 26, 2016
- Brown Dwarfs - September 22, 2016
- Intrusion Rheology - September 19, 2016
- Falsifiability - September 15, 2016
- Fifth Force - September 12, 2016
- Renal Crystal Growth - September 8, 2016
- The Normality of Pi - September 5, 2016
- Metering Electrical Power - September 1, 2016
Deep Archive 2006-2008