Space.com editor-in-chief Tariq Malik talks to FOX Business’ Melissa Francis about NASA’s upcoming helicopter mission on Mars.
Fox Business video.
Everyone loves laminar flow but turbulent flow is the real MVP. A portion of this video was sponsored by Cottonelle.
I got into turbulent flow via chaos. The transition to turbulence sometimes involves a period doubling. Turbulence itself is chaotic motion, it is unpredictable and sensitively dependent on initial conditions. What surprised me is all the ways turbulent flow is useful to us. It is diffusive, meaning it causes mixing. This is useful in jet engines or rocket nozzles (which Destin studies) and is important to achieve in microfluidic devices, which are so small that turbulent flow is actually difficult to achieve. Turbulent flow can energize a boundary layer, which is important to maintain flow attachment over a wing, maintaining lift and delaying stall. Similarly a turbulent boundary layer over a golf ball reduces pressure drag allowing golf balls to fly further. This is the reason for the dimples on golf balls. Flow transitioning to turbulence in the wake of a bluff body can create periodic vortex shedding.
This beautiful phenomenon can be seen in the von Kàrmàn vortex street in clouds viewed from space. Turbulence is everywhere, in the air currents in a room, in your aorta, in the breaths you exhale, in oil pipelines and water pipes, in the flow over cars and ships and planes. Animals have evolved for it (like dead fish swimming up stream) and we have engineered our environment, our planes and golf balls for it. Laminar flow may be nice to look at (which is why we use it in decorative fountains) but turbulent flow does the real lifting. Animations by: Jonny Hyman (Sun, Jupiter, Reynolds, airfoil, Earth time-lapse) Research and writing: AJ Fillo and Derek Muller. AJ also created the wind tunnel golf ball shots Filmed by: Daniel Bydlowski and Derek Muller Additional footage: Images of Jupiter courtesy of NASA Turbulence in air currents by the Physics Girl, Dan Walsh, and Grant Sanderson
Aerogels are the world’s lightest (least dense) solids. They are also excellent thermal insulators and have been used in numerous Mars missions and the Stardust comet particle-return mission. The focus of this video is silica aerogels, though graphene aerogels are now technically the lightest. At one point Dr. Steven Jones literally held the Guinness World Record for making the lightest aerogel and therefore lightest solid. If you’re interested in learning more about aerogels, let me know in the comments as there is a potential trilogy in the works…..
The 50th anniversary of the Apollo 11 mission is being commemorated extensively, including at the White House, where President Trump recognized the crew’s two surviving members. Their conversation included discussion of a new push to travel to the far side of the moon and beyond. Science correspondent Miles O’Brien looks at NASA’s ambitious agenda and how private companies might achieve it first.
PBS NewsHour video.