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Low Flow in Pipes- posted in Ankur's blog

Reynolds Number Less Than 1


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#1 KR

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Posted 02 April 2009 - 05:59 AM

Dear friends,

Is it possible to have Reynolds Number less than 1 for the fluid flowing in a pipe?
If so, what is the its significance.

I am aware Stocks Law implies for the free flowing particles but that's not the case here.

Any help?



#2 Steve McGahey

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Posted 02 April 2009 - 06:28 AM

Well, if the velocity was zero, Re = 0. Therefore, a velocity near zero could result in 0 < Re < 1.

What is the significance of this? Nothing at all.

#3

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Posted 02 April 2009 - 11:24 AM


Motion at low Reynolds number is very majestic, slow, and regular. It is applied in the motion of micro-organisms and anything related to the sub mechanicinal universe. At low Reynolds number the viscous forces dominate, inertia is totally irrelevant. For more details see Life at Reynolds number below:

http://www.tpi.umn.e...alks/Powers.pdf

You can also go to Google and in the search window type:

Life at Low Reynolds Number, EM Purcell 1973

Best regards

#4 DAS-PE

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Posted 02 April 2009 - 07:14 PM


I don't see why not. I have an application where combustion gas will be flowing in a fiber with an ID of 250 micron under vacuum with a Nre of 0.7. Using the laminar flow friction factor of 64/Nre will give an approximation of the expected pressure drop. I am not sure of the accuracy of the final result, but expect to eventually have real confirmation when the testing is done. When you get outside the normal range in research, design is the first step followed by testing.

#5 sheiko

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Posted 04 April 2009 - 11:58 AM

KomalTHEprocessENGINEER,

Is your fluid newtonian? a non-newtonian fluid that follow a power law or a bingham plastic model, for example, will lead to a different Reynolds number formula than a newtonian fluid...

Check out the December 2008 "Fact at your fingertips" from Chemical Engineering Magazine for more: http://www.che.com/d..._Facts_1208.pdf

#6 KR

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Posted 05 April 2009 - 09:02 AM

@All above,

Thanks a lot for your comments and help.

I don't think so its Non newtonian fluid but it seems viscous forces are dominating and it follows plug flow without any mixing/turbulence due to high viscosity.

Regards,
Komal

#7 Qalander (Chem)

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Posted 05 April 2009 - 10:24 AM


Dear,

Then this resembels(very much) to a non-newtonian flow pattern with a slip at the walls having a rod-like flow(as we see for tooth paste etc.)

Hope this helps you somewhat!




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