Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
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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…
Aurora Physics
The auroras at Earth’s poles are much more than pretty lights. This video explains their formation; fluid mechanics (specifically magnetohydrodynamics) play a major role in the convective transport of heat inside the sun as well as the movement of the plasma that makes up a solar storm that interacts with Earth’s magnetic field and produces…
The Tibetan Singing Bowl
The vibration caused by rubbing a Tibetan singing bowl excites standing waves in a Faraday instability on the surface of water in the bowl. As the amplitude of excitation increases, jets roil across the surface, creating a spray of droplets, some of which actually bounce on the surface as it vibrates. For more see the…
Tour de France Physics: Wind Tunnel Testing
Over hours of racing, even a few grams of drag can be the difference between the top of the podium and missing out. For manufacturers as well as for individual professional cyclists, hours of wind tunnel testing help determine optimum configurations of equipment and positioning. During a day of wind tunnel testing, a cyclist…
Tour de France Physics: Time Trials
Unlike road stages in which cyclists can draft off one another to reduce drag, in the time trial a cyclist is on a solo race against the clock with nowhere to hide. As a result, the event features lots of technologies designed to reduce both pressure drag and skin friction on the cyclist. For time…