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Galapagos Week: Pistol Shrimp
One of the most striking things about snorkeling in the Galapagos was how loud it was underwater. There were hardly any boats nearby, but every time my ears dipped below the surface, I could hear a constant cacophony of sound. Some it came from waves against the sand, some of it was the sound of…
Galapagos Week: Marine Iguanas
One of the most unique inhabitants of the Galapagos Islands is the marine iguana. These reptiles live in colonies of thousands and subsist entirely on marine algae. Smaller iguanas are intertidal feeders, grazing on green and red algae when it is exposed near low tide. But the largest iguanas feed near midday by swimming out…
Galapagos Week: Introduction
One hundred and eighty-two years ago today, the H.M.S. Beagle reached the Galapagos archipelago carrying, among others, naturalist Charles Darwin. The ship would spend the next month exploring the islands, and Darwin’s experiences during that time, and the specimens he collected, would ultimately lead him to propose the concept of evolution. I had the incredible opportunity…
Farewell, Cassini!
Tomorrow one of the most prolific and beloved spacecraft missions will come to an end when the Cassini spacecraft makes its final plunge into Saturn. After nearly 20 years in space and 13 years orbiting Saturn, the Cassini mission is close to running out of fuel. To prevent the craft from contaminating one of Saturn’s…
Lift Over Wings
One of the most vexing topics for fluid dynamicists and their audiences is the subject of how wings generate lift. As discussed in the video above, there are a number of common but flawed explanations for this. Perhaps the most common one argues that the shape of the wing requires air moving over the top…
Elastic Bounces
A rigid ball accelerated by a moving surface can only ever move as fast as the surface propelling it. But that’s not true for squishy objects like a water droplet. The composite image above shows the trajectory of a water droplet launched from a moving superhydrophobic surface. As the surface starts rising, it squishes the…
Sunset Vortices
Often our atmosphere’s transparency masks the beautiful flows around us. This spectacular image shows a flight landing in Munich just after sunrise. Low-hanging clouds get sliced by the airplane’s passage and curl into its wake. The swirls are a result of the plane’s wingtip vortices, which wrap from the high-pressure underside of the wing toward…
Jupiter On Display
The rich detail of Jupiter’s atmosphere is on full display in this enhanced-color image from the Juno spacecraft. (Full resolution version here – trust me, you want to click that link.) To the north, on the left side of the image, Jupiter’s Great Red Spot swirls. To the center and right, the cloud bands of…
Adaptive Meshing
The use of numerical simulations in fluid dynamics has exploded over the past half century with new computational techniques being developed constantly. Most methods involve solving the equations of motion (or an approximation thereof) on a grid of points known as a mesh. To accurately capture the physics, meshes must often be quite closely packed…