51–60 of 117 posts
The result of natural/evolutionary selection? Would be interesting to know if there are different types of dandelions (I mean the part used to "fly") used by the same type of seed, each type adapted/optimized for a particular climate (e.g. humid for asian areas, dry for african areas, windy for coastal areas, ...).
Something something "Bumblebees shouldn't be able to fly" something something. How is it we are shocked to find out we are sometimes wrong and not shocked that sometimes we get it right? My critique by the way is the headline, not the actual research. The headline is clickbait IMO, and just as I suppose some don't like my comment (not well thought out, emotional, etc.), the headline is the same. E.g., consider, "Curi…
This reminds me of the thing recently about spiders using electrostatic tension in the air to generate lift with a streamer of silk. Evolution is crazy good at finding and exploiting quirks in physics.
Nature is amazing.
""" """ "" ^v^ "" "" ^v^ "" "" ^v^ "" ... low pressure """...""" held by vortex ######### ### dandelion falling """"""""" """ rising air I wonder about the chances of creating this kind of toroidal vortex above a duct for lift. It seems necessary for the air to pass in the same direction as the lift, yet lift is normally created by throwing air in the opposite direction.
Excuse me, I'm going to go launch SyncTerm now and browse some Mystic and SynchroNet boards.
Earlier quoted context omitted.
You're most likely right, but there is at least one caveat which might be able to help if we're lucky. (I'm a fluid dynamicist, though not an aerodynamicist.) The Reynolds number is only part of the picture. You also need a measure of the strength of the turbulence. A common measure is the "turbulence intensity", which you can think of as the standard deviation of the velocity divided by the mean of the velocity. (Th…
I agree with the importance of the freestream turbulence intensity, but at high Re numbers, it's extremely hard to control it. It can be shown mathematically, using a technique called parabolized stability equations (PSE), that small disturbances amplify rapidly thorough non-linear interactions in the frequency space. Hence, although it's possible to create a laminar flow at high Re number in the lab, it's extremely…
Earlier quoted context omitted.
They're different ways to describe the same phenomenon. "[B]oth 'Bernoulli' and 'Newton' are correct." https://www.grc.nasa.gov/www/k-12/airplane/bernnew.html
> They're different ways to describe the same phenomenon. Well ... they're actually different ways to incorrectly describe the same phenomenon. Wind tunnels are still used for aircraft design because we can't accurately model aerodynamics.
My very rough understanding is that computer simulations of air flow are sufficently accurate for a high percentage of predictions for many kinds of objects. Fair? If not, under what cases does their accuracy suffer? Do we know why?
I am interested in why wind tunnels are sometimes used. Possible reasons I see are:
1. building computer models of an object being tested is sufficently difficult that it is more efficient to test in a wind tunnel
2. computer simulations lose significant accuracy when it comes to certain conditions ... but I don’t know what these conditions are
3. human or policy issues, e.g. some people trust a wind tunnel result more than a computer simulation.
Something something "Bumblebees shouldn't be able to fly" something something. How is it we are shocked to find out we are sometimes wrong and not shocked that sometimes we get it right? My critique by the way is the headline, not the actual research. The headline is clickbait IMO, and just as I suppose some don't like my comment (not well thought out, emotional, etc.), the headline is the same. E.g., consider, "Curi…
Something something "Bumblebees shouldn't be able to fly" something something. How is it we are shocked to find out we are sometimes wrong and not shocked that sometimes we get it right? My critique by the way is the headline, not the actual research. The headline is clickbait IMO, and just as I suppose some don't like my comment (not well thought out, emotional, etc.), the headline is the same. E.g., consider, "Curi…
Complaints about headline bias/clickbaityness or suggesting better links seem to comprise around half of HN comments.
It's like nature's had millions of years to crunch through its own AI / machine learning of evolution and adaptation, and we're about to unleash the same thing on an impossibly faster scale. Imagine the technological breakthroughs that are going to happen. I'm optimistic.