Create an artificial eddy/tornado

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Summary:
Can you create a small Eddy/Tornado with fans with no fixed base or fan above? The idea is to point a fan (or fans) at a fixed location and get an eddy/tornado effect.
Similar to how leaves blow in a circle due to eddy/turbulence formed from buildings and trees, is it possible to make a machine that would create a similar wind pattern IN OPEN SPACE WITH NO FIXED BASE. Obviously, there are tornado machines that are simply emitting visible smoke/fog from a fixed base with a fan directly above it to create the spinning motion.

But I'm referring to being able to create air in that motion anywhere (essentially creating your own turbulence/eddy) simply by pointing turbulent air at it. So with a fan (or two), I would like to walk into a field with leaves, point my experiment at those leaves, and create an eddy. Possible?
 

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I'm not sure what you mean by 'no fixed base'. But this is one (awesome) way to do it:
 
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  • #3
sophiecentaur
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Summary:: Can you create a small Eddy/Tornado with fans with no fixed base or fan above? The idea is to point a fan (or fans) at a fixed location and get an eddy/tornado effect.

I would like to walk into a field with leaves, point my experiment at those leaves, and create an eddy. Possible?
If you see the size of those fans in the video, you will see that even flames need a lot of help. Leaves are relatively massive so they need a fair bit of power to move in an 'impressive' way. However, I regularly use a (single) cordless leaf blower on fallen leaves and they will easily form eddies across a tarmac road. Over a grass lawn, the losses are too great and what I can get is only just identifiable.
I'd suggest that a smoking bonfire would be easier to produce a visible 'tornado'. Two leaf blowers pointing slightly upwards and off centre (tangentially) from a couple of metres away from the fire (adjust to taste) would give the effect. But I suspect your requirement is a bit specific - a special effect for a film, perhaps?
If you want 'impressive' then you'd have to set it up with a number of powerful blowers and a lot of trial and error.

PS Would driving a (high sided) van fast past a pile of leaves (on a road) be acceptable?
 
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I'm not sure what you mean by 'no fixed base'. But this is one (awesome) way to do it:


So can you do that same experiment with only one or two fans? So having the wind blow from just two fans create that same effect, whether it be leaves or a flame. And by base, I mean that you can’t cheat by putting a fan directly above or below. The effect must come horizontally to the object you want to create turbulence in. So I point a fan or two at a flame and it gets that effect. Thanks.
 
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If you see the size of those fans in the video, you will see that even flames need a lot of help. Leaves are relatively massive so they need a fair bit of power to move in an 'impressive' way. However, I regularly use a (single) cordless leaf blower on fallen leaves and they will easily form eddies across a tarmac road. Over a grass lawn, the losses are too great and what I can get is only just identifiable.
I'd suggest that a smoking bonfire would be easier to produce a visible 'tornado'. Two leaf blowers pointing slightly upwards and off centre (tangentially) from a couple of metres away from the fire (adjust to taste) would give the effect. But I suspect your requirement is a bit specific - a special effect for a film, perhaps?
If you want 'impressive' then you'd have to set it up with a number of powerful blowers and a lot of trial and error.

PS Would driving a (high sided) van fast past a pile of leaves (on a road) be acceptable?
I think you’re getting what I’m trying to do. I feel two leaf blowers pointed in the proper direction toward one another would create the leaf-nado that I’m looking for. I wonder would a leaf blower and a hair dryer with hot air make it easier as the hot air would naturally flow to the top. If I had both a cool source of air and hot source, would that work? Maybe a ice fan with hair dryer?

Driving a car really fast would not work, but it gave me a great laugh so thank you. The goal is to do it on a stationary pile of leaves. Thanks
 
  • #6
DaveC426913
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I feel two leaf blowers pointed in the proper direction toward one another would create the leaf-nado that I’m looking for.
I do not think it will. There is nothing to drive it into a loop. I suspect four - or more likely five - leaf blowers will be the minimum.
 
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sophiecentaur
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I think you’re getting what I’m trying to do.
I think so but what is the context? Are we talking any old leaf pile in any old field or is it a set-up for a presentation / trick / film?
 
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I think so but what is the context? Are we talking any old leaf pile in any old field or is it a set-up for a presentation / trick / film?
Just me trying out a hobby/invention to see if I can do it. My friends put the challenge up and I have some spare time coming up to do it. To be able to create mini tornadoes to move stuff in style as opposed to just using a simple leaf blower haha
 
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Merlin3189
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What are the fans for? Wouldn't the fire form a natural vortex?
 
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The fans are to create a vortex, because the fire will not generate a natural vortex...
 
  • #11
hutchphd
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The "natural vortices" are driven by large scale thermal gradients in the atmosphere and clearly there is a critical minimum size required. The classical tornado event involves a cold front advancing on hot humid air. I don't know whether this size requirement is driven by issues of Coriolis forces or viscosity or atmospheric depth.. (Or other stuff ?)
 
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In other words: I don't want to be around a fire that would generate a natural vortex! 😂
 
  • #13
sophiecentaur
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The fans are to create a vortex, because the fire will not generate a natural vortex...
A helical flue would give it a good start but this is all a long way from turning up in a field and doing an impressive 'special effect'.
But, if you want a vortex, water is surely the way to go and it can be done in the kitchen sink.
 
  • #14
hutchphd
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Or the oars from a rowboat! It is amazing to me how deep and long-lived the trailing edge vortex is from an oar (or paddle). Big U shaped vortex off the trailing edge of the oar. Bright sunlight will show it in projection.
And of course the tornado tube
But my favorite is the vortex ring generator made infamous by the Mattel Sonic Blaster. Kids eardrums usually grew back..
 

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