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Old Jul 18th 2018, 03:50 PM   #1
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Simulating scintillation (twinkling)

hi all,

i would like to set up a small lab experiment to try to create visible "terrestrial scintillation", whereby one can see fluctuations in air density (turbulent air), like the rear of the jet in this image:



i have sketched a small setup before i begin; the test will send a projected image through the heat to map what it does to the image as it hits the wall.
i am wondering how best to accentuate the visibility, is it about:

- having lots of heat from a source;
- mixing hot air with cold air;
- controlling the distances between wall, heat source and projector?

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Old Jul 18th 2018, 07:50 PM   #2
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I'm sure you will quickly figure out the best way by experiment...

Be aware the colomb of gas rising from a bunsen burner is not hot air , but other gases , these will have an effect on light ... the effect is all due to the speed of light through the gas , so different gases at the same temp will produce it , or the same gas at different temps will produce it.... you might want to try the jet of unlit gas from a lighter .

The nearer the rising gas colomb is to the light source the greater the effect should be.

A compact hot wire might be better than a bunsen burner . If you can get a car headlamp bulb , carefully break the glass . you will expose the tungsten filament inside , this is quite thick wire and will not burn out if you pass low voltage through it ...just enough to get it red hot . You can then position it close to the light source and pulse it or run it, this will produce a much hotter ,more compact colomb of hot air .

You might not need a projector for this . An led torch that can zoom. Adjust the zoom so that a square image of the led source is projected on the wall.
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Last edited by oz93666; Jul 18th 2018 at 07:58 PM.
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Old Jul 19th 2018, 01:31 AM   #3
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Have a look at <Schlieren Imaging>
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Old Jul 19th 2018, 03:23 AM   #4
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Originally Posted by Woody View Post
Have a look at <Schlieren Imaging>
Ahh this is great. Exactly what I need, thanks.
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scintillation, simulating, twinkling



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