Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Shuttlecock Flow Viz
The flow around a shuttlecock is visualized in a water channel using fluorescent dye illuminated by laser light ultraviolet LEDs. Note the recirculation zone on the upper shoulder. Experimenters can match flow characteristics in water to that in air by matching the Reynolds numbers. (Photo credit: Rob Bulmahn) Updated, thanks to information from the photographer.…
Starting Vortices
Whenever a wing stops or starts in a fluid, it produces a vortex. This 2D numerical simulation shows an airfoil repeatedly starting and stopping, shedding a vortex each time. Note how the line of vortices drifts downward in the wake; this is an indication of downwash. (submitted by jessecaps)
Skydiving Indoors
Vertical wind tunnels like this one simulate the experience of skydiving with air speeds up to 270 km/h (168 mph). Here expert freefallers perform a routine similar to synchronized skydiving. By changing the angle and shape of their body with respect to the air flow, they are able to control their lift and drag to…
Reader Question: Similar Blogs?
thegreatfenceof-deactivated2013 asks: Hello! I was wondering if you follow any similar blogs to your awesome blog? I like the idea of learning about awesome mechanical engineering stuff without learning so if you know of anything please help me out. As you might imagine, I started this blog because I didn’t know of any that were doing…
Un-Mixing a Fluid Demo
Not only is this demonstration one of my favorites, it’s a reader favorite, too. Even though I posted it nearly a year ago, I’ve had it resubmitted over and over. Here’s what I originally wrote: Laminar flow (as opposed to turbulence) has the interesting property of reversibility. In this video, physicists demonstrate how flow between…
Paint Vibrations
Paint vibrated on a loud speaker explodes in multi-colored jets and droplets. Most paints are shear-thinning non-Newtonian fluids (like ketchup, shampoo, or whipped cream), meaning that their viscosity decreases as they are sheared. This allows them to flow more readily once they are perturbed. #
Happy Birthday, FYFD!
Today marks the one year anniversary of FYFD! I’d like to thank each of you for reading, commenting, submitting posts and asking questions. It’s been fun, and, hopefully a bit educational, too. Next week, in addition to new content, I want to feature some favorites from the archives. So take a gander at the past…
Saturn’s Storm Stretches All the Way Around
This picture captured by Cassini in February shows a storm on Saturn stretching all the way around the planet. Unlike Earth and Jupiter, which have numerous storms virtually all the time, Saturn tends to store energy in its atmosphere for decades and then release it all at once in mega-storms like this one. #
Vertical Axis Wind Turbines
Conventional wind turbines feature horizontal axis propellers which must be placed far apart from one another to avoid wake interference. Researchers have found that using vertical axis wind turbines specially arranged to utilize the wake of one turbine to improve the efficiency of its neighbor can produce far more energy per square meter of land.…
Osborne Reynolds and Transition
How and when flow through a pipe becomes turbulent has been a conundrum for fluid mechanicians since the days of Osbourne Reynolds (~1870s): Typically, the laminar-to-turbulence transition is studied mathematically by linearizing the Navier-Stokes equations, the governing equations of fluid dynamics, then perturbing the system. These perturbations will gradually disappear in laminar flow, but if…