Mushrooms don’t rely on a stray breeze to spread their spores; they generate their own air currents instead. The key is evaporation. The mushroom cap contains large amounts of water, and, as this water evaporates, it cools the mushroom and the air next to it. This cool air is denser than the surrounding air, and so tends to spread out and convect. At the same time, though, the water vapor that evaporated from the mushroom is less dense than nearby air, which helps it rise. This combination of spreading and rising air carries spores away from the mushroom cap and, as seen in the video above, can combine to form beautiful and complex currents that spread the spores. (Video credit: E. Dressaire et al.)
Tag: biology
Fluids Round-up – 20 October 2013
Some very cool fluids applications in this week’s fluids round-up. On to the links!
- Like many colleges, MIT has campus myths about those unbelievably windy spots. But, unlike many others, they have a CFD analysis deconstructing the myths.
- Even rocks can behave like fluids sometimes. Check out this article from @s_i_r_h_c on fluid instabilities left behind in rocks.
- Reader Julian de Charentenay demonstrates some DIY aerodynamic analysis on Pixar’s Lightning McQueen. One of the neat features here is using photos of an object to construct a 3D model, a technique I used in my own research at one point.
- Physics.org explains why teapots drip.
- Phys.org reviews a paper suggesting that fluid dynamics influenced the evolution of lung structure.
- io9 discusses new research on how the brain gets rid of waste products, which includes experiments with flow visualization in mice brains.
- Finally, our lead image shows the airship USS Los Angeles moored to the USS Patoka and comes from The Atlantic’s In Focus series on airships past and present.
ETA: I somehow forgot to include the first of the upcoming APS presentations to get wide media recognition: Law of Urination, which has shown up all over the place.
(Photo credit: San Diego Air and Space Museum Archive/In Focus)
Studying Coughs
Bioaerosols–tiny airborne fluid droplets generated by coughing or sneezing–are a major concern for the spread of contagions like influenza. It may be possible, however, to mitigate some of these effects by manipulating biological fluid properties. The video above shows an experimental model of a cough, complete with the generation of bioaerosols from some fake human lung mucus. Contrast this with a cough where the model’s mucus has been treated to increase its viscoelasticity. The treated mucus generates substantially fewer droplets during a cough. The results suggest that drugs that increase viscoselasticity of biofluids may help stem the spread of disease. (Video credit: K. Argue et al.; research credit: M. D. A. Hasan et al.)
Seed-Ejection via Raindrop
[original media no longer available]
We don’t often think of plants as using fluid dynamics aside from capillary action drawing water from their roots, but many plants also use fluid dynamics to disperse reproductive materials. This high-speed video explores the efficacy of splashing raindrops at ejecting seeds from different blossoms. (Video credit: G. Amador et al)
