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Artificial Mirage Lens

Fata Morgana Maxima
  [vote for,

[notexactly]'s Coin-operated astronomical telescope idea got me to thinking about ways to mitigate light pollution in cities using artificial mirages to refract light-waves away from a central observer.

That spawned what I think might be a totally cool idea but I needed to do a bit of research first and I'm not sure it will work... and it's going to be a bit hard to explain.

First off we take a large horizontal parabolic dish, insulate it and turn it into an open chest freezer which spills cold air over its lip in a continuous vapor flow.
Next we take the waste heat and create a gentle tornado effect beneath the underside of the dish.
When this rising hot air meets the cold air there will be turbulence creating a boundary layer between the two.
Before long the cold air will no longer be able to spill out of the dish and it will begin to rotate as well.
Not too long after that the hot air tornado will attempt to close over top of the trapped cold air due to the chimney effect.
The hot air would normally attempt to escape in all directions but a tornado will attempt to remain cohesive, at which point the system will stabilize and lose most of its turbulence as the Coanda effect keeps this tornado hugging the hot/cold boundary layer.

When this happens the inner cold air will naturally assume a convex dome above the freezer dish and the refractive index of the boundary layer will cause light to bend because of the difference in density between the layers.
Adjusting the amount of cold introduced to the system should have the effect of changing the shape of the convex bulge, while tweaking the heat and airflow will allow for ensuring that the heat dissipates at just the right rate so as not to continue to rise once it has reached the peak of the convex bulge.

For an observer or camera within the freezer dish this would be the same as standing within a gigantic adjustable lens. The image seen would be inverted but a telescope within such a system should be able to see much farther than its optics would allow.

Coanda Effect (0.55s in) https://www.youtube...watch?v=NvzXKZNJ7ZU
the hot air is not really perfectly layered. [wjt, Mar 17 2019]

Solar_20Desalination_20Aquaduct [2 fries shy of a happy meal, Mar 24 2019]


       Finding the balance will be difficult; initially you're continuously creating cold AND hot, but once the "hot tornado" closes, your "cold volume" becomes fixed, although there will be energy transfer between the hot & cold zones.
I'm not sure about the interface; as the hot air comes over the "lip", won't it rather mix with the cold air, and become just "air"?
To the lab! (If only I HAD a lab...)
(I haven't forgotten about your other airflow project; it's beyond the capabilities of the "basic" version of the flow analysis software that comes with SolidWorks, so I need to get my hands on the license for the "full" version.)
neutrinos_shadow, Mar 14 2019

       Sweet! I appreciate that and would be happy to chip in on the cost.
I've seen it work with my own eyes so I'm kind of stoked to see if changing the parameters can create a more stable vortex than I was able to.

       As for this little beaut...   

       ... in my head I see the cold air wanting only to sink and the hot air wanting only to rise so the coanda effect coupled with the inherent cohesiveness of the tornado should be the only things holding a very thin layer of almost non-turbulent, although rotating, boundary layer between the densities.   

       If it works, can you imagine scaling it up oh, say to the size of a small crater and making a mega lens from thin air?

       <later edit>   

       As for the volume of cold air in the dish being fixed, I see no reason why some of it can't be held in reserve to be introduced or extracted at will mechanically.   

       I was imagining the cold air to be produced by a chiller at the bottom of the dish, taking air from outside the dish, cooling it, and pumping it in, so it seems the volume of cold air in the dish would be easy to adjust.
notexactly, Mar 14 2019

       Yep, the cold volume is just trapped and adjustable to create a bigger or smaller bubble extending outwards.   

       Figuring out how to smoothe out ripples in the hot airflow is going to be the challenge.
I was thinking that maybe the tornado could be comprised of individually directed columns of air.
Enough of them in a tight enough spiral would act as a Fresnel lens with the curvature.

       Make it weather map scale then the air masses won't mix.Dealing with a fraction of the atom/molecule numbers is usually problematic, take fusion.
wjt, Mar 14 2019

       I've read both of those sentences several times [wjt] and I don't understand. Do you mean that using a crater would be weather dependent? If so I totally agree. This would work best on a planetoid with enough gravity to hold an introduced atmosphere within a crater and not enough gravity to let it escape, but... will it work as I have visualized?   

       If so...   

       Has anyone ever thought it up before?   

       and if the answer to that question is "no"...   

       Then why the fuck do I have to pay anyone to claim it as my own original thought?   

       Sorry, this is drunk Randy asking a rhetorical question asked to the group at large.   

Which assholes decided that I had to pay for my original thoughts?... and how many assholes backed those other assholes up?

       I always figured that if by some fluke of fate I made it to fifty I'd be old enough then and somehow just understand, but nope, my original thoughts belong to the state unless I can afford to purchase them from people who can not have original thoughts of their own... and my 'betters' have allowed it.   


       Like the spoiled children of billionaires given a Porsche at fifteen.
Like your Grandfathers didn't die for that shit you dumb sons'o...

       Aaaaauuuurghrgrhrgrg !!!!!!!   

       Explanation: I don't think that air flows of varying temperature can be controlled accurately on a small scale. Weather does it with vast numbers of molecules with gravity and probably magnetism. Your idea uses velocity, which is a great initial idea but the pattern may not be good for forming a slow layered bubble needed for lensing.   

       The larger the scale the better the layers unless there are ways to differentiate the air more, to reduce the scale. Patterns of the energy of heat would be good, if there was such a thing.   

       Aaaaauuuurghrgrhrgrg Aaaaauuuurghrgrhrgrg   


       Aaaaauuuurghrgrhrgrg Aaaaauuuurghrgrhrgrg   

wjt, Mar 16 2019

       : ]   

       // The larger the scale the better the layers unless there are ways to differentiate the air more, to reduce the scale. Patterns of the energy of heat would be good, if there was such a thing.//   

       Not sure that I agree. Ripples will be the nemesis to obtaining a clear magnification. The larger the surface area, the greater the variables involved and the Coanda effect will only bend the tornado so far before it overpowers and separates from the volume of cold air. There will for sure be a maximum size past which no clear image can be obtained from within.
I could make one of these on a small scale in my garage, where there is no wind and I can control external variables, but a large exterior installation would be subject to constantly changing conditions.

       hmmmm Mars would have the right conditions for a large version. Massive enough that gravity would allow for trapping an atmosphere within deep enough craters to keep it trapped and minimal weather patterns... but on Earth? Wind will always be a factor.   

       I retracted my ommmmmmmmm. I don't know if that aurgrghghgh shoulder chip's going away until I get the rights I was born with to my own thoughts back from the assholes who saw fit to steal them. All of the sacrifices for those rights rendered meaningless with the stroke of a pen by sad, greedy, (the word evil springs to mind), little con-men.
Their time is almost up.

       As for the scale the Coanda effect, it is still going to be quite turbulent. The scientific layering in diagrams would be optimal. In reality the molecular vectors would be all over the place in accordance with a normal distribution relating to position in the effect. Athough, light can be affected. See link
wjt, Mar 17 2019

       Cool video.   

       In all of those demonstrations the airflow was turbulent. With a tornado that turbulence becomes conservation of angular momentum and gyroscopic effects emerge. A rotating coanda effect will behave much differently than any of the research I've been able to find much the same way that a tornado vortex ring doesn't seem to have any research behind it yet.   

       Nothing new under the sun my butt...   

       True that. It is a very large place our little fold is in.
wjt, Mar 17 2019

       Our little fold is brilliant, diverse, and can communicate past differences which would be roadblocks in almost any other setting.
As group there is little we don't know, and there's a lot of nooks that could use some light.

       That's why we have a halfbakery against the world category.   

       Seems to me what's needed is a transparent chimney, partly curved but with flat apertures. How tall? Who knows, but that would depend partly on scale and the intrinsic situation of an open heat transfer within its larger environment, and partly on the height requirement to allow a strong occlusion of the cold air within.   

       The atmosphere of Earth generates models of the interface continually at all levels but what we observe can present itself at a meter off the ground, so the scales are very imprecise.
reensure, Mar 18 2019

       hmmm, the chimney will need a fresh air intake at its base or its effect will draw air down from above and create a doughnut shaped back-eddy on the lens surface.   

       Occlusion is a good word for this. A stable cyclonic cycloptic occlusion.   

       //The atmosphere of Earth generates models of the interface continually at all levels but what we observe can present itself at a meter off the ground, so the scales are very imprecise//   

       I think we could make this mirage-lens very precise, and I wonder if there are natural mirages caused by the boundaries between zones like where the troposphere meets the stratosphere. As it is Fata Morgana mirages can allow a person to briefly glimpse objects beyond the curve of the Earth for the observer at ground level. If those effects translate through the various atmospheric densities you might be able to see half way around the planet given just the right conditions.   

       <later edit> Heh, that came out as Fat Morgan mirages first time through and now I will never again be able to either see or think about mirages without calling them Fat Morgan in my head.

       The last two annos, as well as one that I was sure I spotted here the other day but cannot find again, remind me of an idea that I was sure I read several years ago (either at this establishment or on [wbeaty]'s site) but was unable to refind when I searched for it in 2015 (when I was planning to attempt to build a working model). That idea was a solar chimney that would reach up to cloud altitudes and create rain on desert islands.
notexactly, Mar 19 2019

       Was it this one? [link]   

       just as an aside, I have heard of highly structured things like micromirror arrays and these might do something like, "to refract light-waves away from a central observer [benefitting an observatory]"   

       Noting mirror-mirages are well known to exist perhaps an IR laser could produce vast arrays of 1 cm tuned mirror mirages at a distance, in the sky, to customize the light that actually reached the telescope. At IR-laser mirror arrays making a prism out of air that edits out the streetlight emission frequencies is just barely plausible.
beanangel, Mar 24 2019

       Hey I just realized something else about this concept if it actually works.
Any light source from within the dish will be collimated as it passes the boundary layer and could be made to focus at any range.

       Not that. The thing I'm remembering was a vertical tower, probably held aloft by buoyancy and/or the upward motion of the air inside it.
notexactly, Mar 28 2019


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