Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
River Paths
As a follow-up to this recent post about river meander, check out this video from Numberphile about some of the mathematics behind the path of rivers. A river’s course is typically much longer than the direct distance between its origin and outlet; the ratio of these two distances is the river’s sinuosity. The fluid dynamics…
Shrinking Red Spot
Observations show Jupiter’s iconic Great Red Spot is shrinking, most recently at a rate of more than 900 km a year. As it gets smaller, the storm is also changing shape and becoming more circular. Scientists don’t yet have an explanation for the shrinkage or its recent acceleration, but this is unsurprising given the rich…
Separating Flow
Flow separation occurs when a fluid is unable to flow smoothly around an object. In the case of the photo above, fog is being used to visualize flow around an airfoil at a large negative angle of attack. The incoming flow stagnates at a point on top of the airfoil, and streamlines on either side…
Melting Ice Sheets From Below
A new study of ice sheets in West Antarctica has made major news this week with the announcement that the ice melt in this region is unstoppable and may raise sea levels by more than 1.2 meters. Part of what makes the ice sheet so unstable is the local topography, shown schematically in the animation…
Double-Diffusive Convection
Convection can be driven several mechanisms, including temperature and concentration differences. The video above shows convection between a a layer of sucrose solution and a layer of saline solution. Initially, the lighter sucrose layer sits over the denser salt water. After the interface is perturbed, the differences in concentration – and thus in density –…
Forming a Vortex
[original media no longer available] Vortex rings show up remarkably often in nature. In addition to being the playthings of dolphins, whales, scuba divers, humans, and swimmers, vortex rings appear in volcanic outbursts and spore-spreading peat mosses. Vortex rings even occur in blood flow through the human left ventricle in the heart. In each of these cases, the…
Graduation!
Last night I walked across the stage as a student for the last time, receiving my PhD in aerospace engineering and getting hooded by my advisor in a tradition with roots back to medieval scholars. Even more so than the defense, it marked an official end to my PhD. None of that is really fluid…
Space Balls (of Water!)
The microgravity environment of space is an excellent place to investigate fluid properties. In particular, surface tension and capillary action appear more dramatic in space because gravitational effects are not around to overwhelm them. In this animation, astronaut Don Petit injects a jet of air into a large sphere of water. Some of the water’s…
Why Ketchup is Hard to Pour
Oobleck gets a lot of attention for its non-intuitive viscous behaviors, but there are actually many non-Newtonian fluids we experience on a daily basis. Ketchup is an excellent example. Unlike oobleck, ketchup is a shear-thinning fluid, meaning that its viscosity decreases once it’s deformed. This is why it pours everywhere when you finally get it…