Quote:
Originally posted by bigben2k
Myv65: You wrote "Laminar flow will be upset by any change in cross sectional area, shape, or sometimes even deviation from a straight path". That reminded me that the channel width in this design varies from 1.0mm to 2.0mm. I still plan on adding more turbulence, but I'd like to know your opinion on this varying channel width, as it relates to turbulence.
To throw the discussion into turbulence, I'll post a link to this most interesting article by Mike Larsen.
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I have never spoken (at least that I know of) to Mike Larsen. I'll say only a couple of things about that article, which I did read quite some time ago.
One, those diagrams look suspiciously similar to those that exist in the fluids text I used in college. [edit start]
Glad to see credit was given to the source. [edit end]
Two, all those diagrams have the same basic premise. They all pertain to an "infinite flow field". This means the conditions upstream of the "x=0" or the "entrance point" are uniform. Once you toss out this premise (as will happen anytime you go through a bend or real life fitting) things get a whole heckuva lot more interesting and complicated.
To put it bluntly, I thought it was a decent discussion but rather misleading. Call it the difference between understanding and applying concepts. Pretty much all students that make it through introductory fluids will understand the concepts of laminar/turbulent, entrance length, etc. Not too many really get an appreciation for the practical aspects of how these things exist in real life.
A lot can happen when trying to write technical stuff for a non-technical audience. Believe me I know. Perhaps Mike has a solid grasp on all of this and didn't wish to bog down the readers. I can't say for certain.