Dylan said:
I'll say to you what I said to Elk, ie, warm gases SHOULD ascend a conduit in a spiral motion IN A PERFECT LAB, but in reality, they don't. The perimeter cooling creates eddies and vagaries in the fluid shear strength (of the gas, that is) which destroy any noticeable (by our means, anyway) spiralling.
Well, that seems a lot different or simply better of an explanation......So you agree that in theory they should spiral, and probably do to some extend, but are messed up (as I mentioned) by a number of factors. I think we can agree on this as the everyday truth, as it has been confirmed by one of the top experts on chimneys, Mr. John Gulland. Here is what he had to say:
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As I learned over twenty years ago by hanging out with the
slightly looney Phd aerodynamicist in the research division
of Canada Mortgage and Housing Corp., everything to do with
air pressures and flows is complicated and messy, so I'm not
sure there is a simple yes or no answer to that question. I
suspect what you have is a ragged, swirling mixture rising
in the chimney, with lots of eddys and currents, and that
whether those eddys and currents get organized into a swirl
all in one direction has to do with the surface
characteristics of the flue.
The behavior of a plume of hot gas rising, for example, from
a well-built bonfire in perfectly still air doesn't suggest
to me that there is a normally present force that tends to
organize the plume into a 'unidirectional swirl' (if I may
put it that way). As I recall it sometimes swirls and
sometimes doesn't, but it is always fairly random and messy.
I don't know of a technical paper that weighs in on the
question of swirl or not in a flue. I have certainly heard
sweeps and other non-scientific experts confidently express
the view that a plume rises in a swirl inside the chimney,
but I never took the issue seriously enough to investigate
it thoroughly.
If I had to guess, I'd guess it is a crapshoot whether the
plume swirls in one direction or not.
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So, again, it appears that is sometimes swirls and sometimes not. It may swirl in one direction......as John said, it's a crapshoot - a gamble.....
We sure aren't going to solve it here, although I would say that it is not wrong to assume that smoke swirls within a round chimney although not always in an organized fashion.
I would also suggest that insults and such things have only to do with the swirling of egos, and nothing to do with the subject at hand.
