Laminar Flow and Friction?

[healingtobias]

I've been looking at round vs square burn tunnels and I'd like some feedback from the experts, or some advice on where this might have already been discussed. docbb gave me some links which were totally awesome! Thanks by the way. But one wasn't in a language I can read and the other didn't address my question. So here is my thinking:

If we say that we make a round chamber and a square one, both with the exact same cross-sectional area, then the round one ends up having about 12% less surface area than the square one. Wouldn't this decrease friction along the walls thus decreasing laminar flow? And if so, would that not improve the burn overall? I saw some videos on the link docbb sent me regarding liquid heat exchangers improving flow through a round pipe with a spiral, but there was nothing on square tubes. And does liquid fluid dynamics equate to gaseous dynamics as with fire?

I'm sure I'm over-thinking it but I'm a nerd and enjoy that part of the process.

Thanks all,
Tobias

[Deleted]

Dec 23, 2013 10:31:53 GMT -8 healingtobias said:

And does liquid fluid dynamics equate to gaseous dynamics as with fire?

Gaseous streams will become compressible at high speeds.
en.wikipedia.org/wiki/Mach_number

For castings friction could be decreased by dimples,
which may also increase heat transfer.

[healingtobias]

Thanks!
What do you mean by dimples?

[Donkey]

Like a golf ball..
?

[satamax]

Karl, that's intresting.

Tho, do we want heat transfer in the cast parts? May be not. Tho, a bell with lots of dimples or stubs of bricks sticking out etc could be intresting.