Plants and dolphins are not the only ones in nature creating vortex rings. Volcanoes are known to produce them as well. The vortex ring forms when gas is rapidly expelled from the volcano (much the same way as with a vortex cannon); the rings are visible in the video above because smoke has been entrained into the vortex.
Month: August 2010
Fire Tornado Formation
The phenomenon of a fire tornado caught our attention recently after the BBC published footage of one in Brazil. While it may look like the fiery wrath of a god, the fluid dynamics of a fire tornado are relatively simple (see figure above). Still, they make for some pretty wild video.
Tempus II
While not strictly fluid mechanical Philip Heron’s Tempus II features some great slow-motion action of fluids. (Submitted by @ftematt)
Vortex Shedding
Whenever a bluff (i.e. non-aerodynamic) body is placed in a flow of sufficient Reynolds number, it will shed periodic vortices, creating a pattern known as a von Karman vortex street. The animation above shows the phenomenon in the wake of a cylinder, but vortex streets form behind many other bodies as well, including islands. Each vortex shed causes forces on the body and alternating vortices can cause the body to vibrate. This is what causes suspended power lines to “sing” in the wind. #
Soap Bubbles in High-Speed
Everyone has played with soap bubbles. They’re an excellent demonstration of surface tension, even more so when filmed at 5,000 frames per second.
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.
Wingtip Vortices in Flight
This NASA Langley Research Center test shows real-time flow visualization of the wingtip vortices off a C-5A Galaxy aircraft.
Drinking Coffee in Space
Operating in microgravity disrupts a lot of everyday routines. However, astronauts have learned to take advantage of surface tension to enable them to drink their daily coffee from a cup still.
Phytoplankton in Bloom
Phytoplankton blooms, aside from giving us gorgeous eddies of blue and green, can reveal how ocean currents are mixing. Blooms typically occur where nutrients are being washed together. #
The Sound of Helium
Gases of different density are good for more than just physics demonstrations. They also affect the transmission of sound waves, thereby altering our perception of pitch. As fun as sulfur hexafluoride is, though, don’t go playing with it at home; it’s an extremely potent greenhouse gas.
