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Non newtonian pressure drop

Non newtonian pressure drop

Non newtonian pressure drop

(OP)
Good morning,

I have to pump a non-newtonian fluid (an emulsion). I know some lab properties of the fluids (enough to estimate the apparent viscosity) but I'm not sure of what set of equations I should use. Do you have any good reference where I can find simplified equations for make a good estimation of pressure drop in pipes for this kind of fluids?

(pd: I have read some papers where the autors suggest to use the same equations for newtonian and non-newtonian fluis, changing only the viscosity. What do you think?)

Regards,

lij.

RE: Non newtonian pressure drop

It depends.  What is the rheology of the fluid?  Most, but not all, emulsions are shear thinning.

Good luck,
Latexman

RE: Non newtonian pressure drop

(OP)
Hi,
You're right Mr Latexman, it is shear-thinning.
lij

RE: Non newtonian pressure drop

Then as long as the shear rate created in the pipe is greater than the shear rate of the lab viscosity measurements, using the lab viscosity in a Newtonian method is conservative.

I gave an excellent reference a while back.  Do a search here and in the Chemical Engineering forums and see if you find it.  If not, let me know and I'll repeat it.  It was a series of articles in Chemical Engineering Magazine.

Good luck,
Latexman

RE: Non newtonian pressure drop

BI,

Agree.  If one takes the easy way out, there is usually a catch!

Good luck,
Latexman

RE: Non newtonian pressure drop

For the most part you just need to formulate some equation to relate viscosity to (normally via shear to) vs velocity.  

It gets tricker if your viscosity varies with time at various velocities, or has other more devious complications.  

"I am sure it can be done. I've seen it on the internet."  BigInch's favorite client.

"Being GREEN isn't easy." Kermitfrog http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

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