Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Circulation Around an Airfoil
As a followup to yesterday’s question about ways to explain lift on an airfoil, here’s a video that explains where the circulation around the airfoil comes from and why the velocity over the top of the wing is greater than the velocity around the bottom. Kelvin’s theorem says that the circulation within a material contour remains constant…
Hawk Moth Hovering
The hawk moth (Manduca sexta) flies quite similarly to a hummingbird, able to hover over the flowers from which it feeds by rotating its wings as it flaps. This constant change in angle of attack allows it to maintain lift while remaining stationary in space. Researchers study the stability of such miniature hovering flight by…
Reader Question: How Airfoils Produce Lift
doughboy3-deactivated20120305 asks: I’m a Undergrad Aeronautical Engineering student. I’m curious as to your opinion as to how airfoils produce lift. I know the usual theory told in this situation. However my aerodynamics professor says that there are many things going on during the flow around an airfoil. I’m hoping to get a better idea of the…
Reader Question: How to Get Started in Fluid Dynamics
unboundid-deactivated20131116 asks: Hi. I’m a freshman engineering student at UCSD, and I was hoping to get more into fluid dynamics. Could you possibly give a quick shake-down of what I should look into if I’m just kind of starting? I want to either work in studying specifically fluid dynamics or in studying interactions of oil and…
Supersonic Stellar Jets
Astronomers studying stellar jets–massive outflows of gases and particles pouring from the poles of newborn stars–are finding reasons to turn to fluid dynamicists to understand the timelapse videos they’ve stitched together from multiple exposures from the Hubble telescope. Usually astronomical events unfold on such a slow timescale that our only view of them is as…
“Tidal Wave” vs. “Tsunami”
This is part of the trouble when the same term has a scientific meaning and a lay meaning. See also: fluid.
Colliding Jets
Two jets of sugar syrup collide and interact to form very different patterns. On the left, the two jets have a low flow rate and create a chain-like wake. The jets on the right have a higher flow rate and produce a liquid sheet that breaks down into filaments and droplets. The result is often…
Vortex Ring Collision
Two vortex rings collide head-on in this video. If their vorticities and velocities are matched in magnitude and opposite in direction, their collision results in a stagnation plane–essentially a wall across which the fluid does not pass. In reality, there are slight variations that result in non-zero velocities where the vortices meet, so some mixing…
Ejecting Drops
Large droplets ejected from a liquid pool do not coalesce immediately back into the whole. Instead, a thin layer of air gets trapped beneath them, much like the oil lubricating bearings. The weight of the droplet causes the air to drain away, and eventually the droplet comes in contact with the pool. Some of the…
Freezing in a Microchannel
Fluid mechanics at the microscale can behave quite differently than in our everyday experience. Microfluidic devices–sometimes known as labs on a chip–are becoming increasingly important in research and daily life. For example, the test strips used by diabetics to check their blood sugar levels are microfluidic devices. In this video, researchers use a microfluidic channel…