This simulation shows how tsunami waves are expected to spread from the epicenter of the Japanese magnitude-8.9 earthquake. Note the complicated interference and reflection patterns. The main wavefront moved at a speed of about 230 m/s (830 km/h) between Japan and Hawaii.
Tag: fluid dynamics
Earthquake-induced Whirlpool
In the wake of the 8.9-magnitude earthquake that hit Japan today, a massive whirlpool has appeared off the coast. It does not appear to have a downdraft, so it’s not a true vortex; it looks as though the residual energy released from the quake has caused circulation in this region.
Solar Prominence
[original media no longer available]
In this stunning video of a solar flare and prominence captured by NASA’s SDO mission, plasma erupts from the surface of the sun preceded by a massive shockwave (near center of frame, heading downward). The motion of the plasma is dictated not only by classical fluid mechanics but by the influence of the sun’s magnetic field in what is known as magnetohydrodynamics. (submitted by Caleb)
Discovery Wingtip Vortices
Wingtip vortices mark the path of Discovery as she makes her final landing. Though not always visible, these vortices are generated by any lifting body planform and can be a major source of induced drag on the craft. Here the vortices are visible because the low pressure in the core of the vortex caused a local temperature drop below the dew point, thus causing condensation. Such vortices persist for significant lengths of time in the wake of aircraft; they are a major source of wake turbulence, which limits how frequently aircraft can take-off or land on a single runway. (Photo by Jen Scheer)
Hungarian Fire Tornado
This fire tornado formed over a burning plastic-processing plant in Hungary a week ago. Fire tornadoes aren’t rare, but footage of them is because they typically occur amidst wild conflagrations. Take a look at our explanation of how they form. #
High-Speed Cooking
I suspect demonstrating fluid mechanics was not what this cookbook had in mind when they filmed creamer poured into coffee at 2000 fps, but there’s some awesome droplet breakup, crowning, roiling turbulent mixing, and even some deformed Worthington jets here. It’s a reminder that, even though we may not notice it, fluid dynamics are all around.
Wright Brothers’ Wind Tunnel
A large part of the Wright Brothers’ ultimate success in creating the first powered heavier-than-air craft came as a result of work done in their homemade wind tunnel, shown above. In the aftermath of the failure of their 1901 Glider, the brothers decided that the lift and drag data they had used from Otto Lilienthal must be inaccurate. They built this wind tunnel and its force balances to measure lift and drag on two hundred different airfoils themselves and were rewarded with far more successful flights with their 1902 Glider, which led directly to the Wright Flyer in the following year. #
Pouring Paint
In this artwork by Holton Rower, paint (typically a non-Newtonian fluid) is poured down a rectangular prism; the result is a neat demonstration of shearing in laminar flows. Paint is usually shear-thinning, meaning that its viscosity decreases under shear; this is why the color stripes on the vertical panels expand more than those on the horizontal surfaces do. # (submitted by Stephan)
Hotwire Anemometry
Hotwire anemometry is used in experimental fluid dynamics to measure velocities with high temporal resolution. The boundary layer crosswire probe shown here was used for turbulence research. Between the prongs, which are about the thickness of a sewing needle, are tiny wires about 3 microns in diameter. A human hair is about 80 microns in diameter. Hotwires actually measure voltage; when part of an electrical circuit, the hotwire’s temperature rises above ambient. As air flows over the wire, it cools, which causes the wire’s resistance to drop. By tracking this change in resistance, it is possible to determine the speed of the air moving over the wire.
Cornstarch Monsters
The patterns formed when vibrating a liquid on a speaker cone are standing waves known as Faraday waves. With a large enough amplitude, this produces some very cool effects with a shear-thickening non-Newtonian fluid like oobleck. (It would actually be interesting to see what happens when you vibrate a shear-thinning liquid like shampoo…) This video also details how you can set up this demonstration yourself at home.
