Airflow around a vertical cylinder (such as a cigar)

[DaveC426913]

TL;DR Summary

Which side of a cigar in the wind will burn faster?

Writing from Cuba.

This is canoeing:

There are multiple causes for it but the one I'm interested in is when it is caused by directional air flow (AKA wind).

If a breeze is blowing across my stogie from the same direction for an extended duration, one side will burn down much more than the other. I would have thought it would be the side facing the wind but I can never be sure. I try to experiment but I mess it up every time.

I suspect the opposite is true: the windward gets its heat stolen and carried to the leeward side, where it burns faster.

Does anyone know of any relevant physics that codifies this phenomenon?

 

[phinds]

I suspect the opposite is true: the windward gets its heat stolen and carried to the leeward side, where it burns faster

I doubt it. The extra oxygen should make the upwind side burn faster. Try it with a hair dryer blowing on one side; that should solve the issue.

 

[Baluncore]

I suspect the opposite is true: the windward gets its heat stolen and carried to the leeward side, where it burns faster.

I think that explains it.

Bush fires in strong winds ignite vehicles and structures from the down-wind side. On the upwind side, flame is blown up and off the structure by the wind. An eddy forms downwind, where embers circulate until they are caught low down, starting a fire maybe 10 minutes after the fire front passed.

With a cigar, I expect hot combustion products will gather in the lee. That will dry and heat the surface, initiating earlier combustion of the outer wrapping in the eddy.

 

[phinds]

@DaveC426913 how about you try my suggested experiment and let us know how it works out.

 

[DaveC426913]

@DaveC426913 how about you try my suggested experiment and let us know how it works out.

Perhaps when I get home. Seems a less than ideal way to enjoy a cigar, but...

 

[256bits]

TL;DR Summary: Which side of a cigar in the wind will burn faster?

Does anyone know of any relevant physics that codifies this phenomenon?

Which side burns faster - top or bottom - in still air?
With no sideways wind, the natural convection will transport heat to the top, and the bottom will receive fresh new air. No swirls or eddies to be seen swirling about the cigar from this non-turbulent flow.
So does the top burn faster, or the bottom?

So what wind speed are you looking at - slight breeze, unpleasant breeze, blowing off hats breeze, hurricane force?

If you notice the cigar burning faster on one side, is it attributable to the wind, or in addition to some other cause?
Such as sucking on it with one side facing up to heat the end.
and then holding the cigar with the side that was previously up now facing another direction to let the end smoulder.

 

[Baluncore]

I think you would turn the cigar as you smoked it, so the wind effects would tend to average out.

The other explanations confound the wind analysis.

One reason given for canoeing, is that a poorly rolled cigar, has varying thickness or grade of outer leaf, that burn at different rates. Buy a better quality, a more expensive cigar. Another reason given is poor storage, where one side of the cigar has higher moisture than the other. Store the cigars so that moisture, throughout the cigar, can equilibrate. Packaging is important.

 

[DaveC426913]

Which side burns faster - top or bottom - in still air?

It should burn evenly under that small an effect.

With no sideways wind, the natural convection will transport heat to the top, and the bottom will receive fresh new air. No swirls or eddies to be seen swirling about the cigar from this non-turbulent flow.
So does the top burn faster, or the bottom?

I think you've got a point. I suspect top burns very slightly faster.

So what wind speed are you looking at - slight breeze, unpleasant breeze, blowing off hats breeze, hurricane force?

Unpleasant breeze, by your rating system.

If you notice the cigar burning faster on one side, is it attributable to the wind, or in addition to some other cause?

Other factors being equal, I know it burns unevenly in a strong breeze.

What I always forget is which way I had it when it did that, and thus which way to to turn it so it will even out.

And that is the answer I seek.

 

[phinds]

And that is the answer I seek.

SO ... quite guessing and do my suggested experiment !

 

[DaveC426913]

And speaking of airflow around vertical cylinders I was facinated to learn that these spiral wings on smokestacks are NOT stairs.

Know what they're for?

 

[DaveC426913]

SO ... quite guessing and do my suggested experiment !

I will eventually, but I'm also interested in the theory of it.

 

[Baluncore]

Know what they're for?

Yes.
And did you know they are twisted the opposite way in the Southern Hemisphere.

 

[Lnewqban]

... Know what they're for?

Copied from:
https://seas.harvard.edu/news/2021/...g-winds-and-flowing-water-look-marine-sponges

“Today’s approaches for reducing vortex shedding don’t actually prevent it from happening,” .... “Rather, they simply shift the shedding to a more downstream location. In contrast, the sponge’s ridge design completely stops vortex shedding across a wide range of flow regimes.”

Please, also see:
https://en.wikipedia.org/wiki/Kármán_vortex_street#Solutions

 

[DaveC426913]

Yes.
And did you know they are twisted the opposite way in the Southern Hemisphere.

You jest!