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Air is not viscous, nor is it heavier than air
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#1 (permalink)      3/1/2020 12:51:30 PM US Central   quote/reply + tips
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gph61
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Air is not viscous, nor is it heavier than air
The airflow design in this RDA is a good example of a common misunderstanding in the properties and behaviour of air. This misunderstanding is showing no signs of going away on its own so I thought I'd post this.

Air will not fall in from the top cap onto those ramps on the deck and down under the coil:


It's going to be drawn down the channels in the top cap via vacuum and immediately turn straight back up to the drip tip.

That's not to say great flavour can't be produced with top airflow because I know it can. What I'm saying is far too often designers are applying attributes to moving air that make it somehow more viscous and or heavier than the air in the same atmosphere around it.
If I'm ignoring you it's because you're fallacy impaired. Here's hoping you rectify your problem so that we might have a sensible conversation.
#2 (permalink)      3/1/2020 12:55:16 PM US Central   quote/reply + tips
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gph61
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+1 details
Here's a decent shot of one of the two airflow channels in the top cap:



The air is coming in there and going straight back up to the drip tip.
If I'm ignoring you it's because you're fallacy impaired. Here's hoping you rectify your problem so that we might have a sensible conversation.
#3 (permalink)      3/1/2020 12:59:28 PM US Central   quote/reply + tips
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gph61
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To achieve what they mistakenly believe they are achieving they could put a roof over the ramps in the deck such that when the top cap was installed the air would be forced under the coil.
If I'm ignoring you it's because you're fallacy impaired. Here's hoping you rectify your problem so that we might have a sensible conversation.
#4 (permalink)      3/1/2020 1:44:22 PM US Central   quote/reply + tips
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carrion4worm
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CHeck your title.
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#5 (permalink)      3/1/2020 1:49:58 PM US Central   quote/reply + tips
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gph61
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carrion4worm wrote:

CHeck your title.

If you mean the title boils down to saying "air is not heavier than air" it was intentional.

Take this RDA for example, the air coming down from the top cap would need to be heavier than the air sitting below the coil to flow down those misguided "air ramps" and displace it, instead of just going straight up to the drip tip.


Edited on 3/1/2020 at 2:31 PM. Reason:
If I'm ignoring you it's because you're fallacy impaired. Here's hoping you rectify your problem so that we might have a sensible conversation.
#6 (permalink)      3/1/2020 3:15:35 PM US Central   quote/reply + tips
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gph61
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I'm guessing the designer of this tank mistakenly envisions a beautifully curved sweeping path of air coming down the pipes in the top cap, flowing down the ramps and under the coil then back up the other side to the drip tip.

How they envision two seemingly viscous air flows opposing each other like that I don't know because they lost me at the ramps. Maybe they think the two streams hit underneath the coil then turn up and hug around it before merging at the top?

Anyway, my point is there's far too much intuition in air design and far too little hard science.

Edited on 3/1/2020 at 4:10 PM. Reason:
If I'm ignoring you it's because you're fallacy impaired. Here's hoping you rectify your problem so that we might have a sensible conversation.
#7 (permalink)      3/1/2020 4:22:14 PM US Central   quote/reply + tips
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MotoBlue
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gph61 wrote:

It's going to be drawn down the channels in the top cap via vacuum and immediately turn straight back up to the drip tip.




Air has mass so it must have momentum. It would not flow as you describe.

Watch some of Morten Oen's youtube videos.

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#8 (permalink)      3/1/2020 4:51:07 PM US Central   quote/reply + tips
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gph61
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I have watched Morten Oen's videos and think he's doing great. I'm a fan. This video is showing the effect of a relatively tiny pressure reduction in a relatively expansive chamber. This atty has a much smaller chamber volume with the same, relatively not so tiny anymore, pressure reduction. The comparison is apples and oranges.

Yes moving air must have momentum but enough to overcome the vacuum coming from this drip tip the moment it exits out of the top cap holes just a few mm below it?
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#9 (permalink)      3/1/2020 4:52:55 PM US Central   quote/reply + tips
Markezz
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Air is 'thinner' at a higher altitude is it not?
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#10 (permalink)      3/1/2020 5:01:52 PM US Central   quote/reply + tips
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gph61
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Markezz wrote:

Air is 'thinner' at a higher altitude is it not?

It contains less heavier elements like oxygen at higher altitudes and is under less pressure because there's less mass above it. The distances we're talking about here are negligible though.

If I'm ignoring you it's because you're fallacy impaired. Here's hoping you rectify your problem so that we might have a sensible conversation.
#11 (permalink)      3/1/2020 9:43:45 PM US Central   quote/reply + tips
xandwhyisY
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I don't agree with your statement, but I understand the argument.
While the atty is under pressure the air will travel a relatively straight path, but the velocity at which you apply that pressure can change that path drastically. Then when you add other variables like coil, wick, liquid, condensation etc., any of these small variations can create a hell of a lot of turbulence, which in turn leads to a poor vape.
It's also good to remember that heat is being applied at the centre of an RDA, and that after a draw or two the internal temp of the RDA is going to be hotter than the cooler air being drawn in. Now you have intense heat at the centre, a hot internal chamber, and cool high velocity air rushing in through the airflow. The cool air you are drawing in is denser than the air in the chamber, this is why the path is not a straight shot up towards the drip tip. The air must make contact with either the coil or the airflow coming in from the opposite side of the RDA in order to change direction.

With this RDA it's a tough call, I'd have to have it in my hands. The airflow on this one seems to be off-centre. That's not a bad thing, but it does generally mean you have to put more thought into the build and wicking than I like. If the price ever drops around $15 I'll buy one and get back to you :)