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Newtonian Pressure Drop vs Non-Newtonian Pressure Drop

10/23/2016 5:57 PM

Hi,
I did some experiments on Newtonian and non-Newtonian fluids measuring the pressure drop through a horizontal pipeline. The Newtonian two-phase flow was water+air and the non-Newtonian was (water+xanthan gum)+air.

I prepared 2 samples (2 concentrations) of the xanthan gum solution 1g/1L (995 kg/m3) and 2g/1L (990 kg/m3). I am wondering if it is logical that the Newtonian pressure drop was bigger than the non-Newtonian one?! Also the 2g/1L sample should've been with a higher density comparing to the 1g/1L!
Thanks

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#1

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/23/2016 9:02 PM

Rixter answered the question in your duplicate thread, where you presented no salient facts.

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#4
In reply to #1

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/24/2016 12:38 AM

I gave more details on there. Thanks a lot.

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#2

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/23/2016 9:20 PM

If you find out what Non Newtonian means for your fluid then you might have an answer.

Means find out what category your fluid falls into!

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#3
In reply to #2

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/24/2016 12:10 AM

The fluids I am working on are (xanthan gum+water) + air. It is a shear thinning fluid gets less viscous as the shear stress increases.

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#5
In reply to #3

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/24/2016 2:34 AM

So what do you expect for the pump pressure from this? You already arrived at the conclusion. Fix it all together now and next you use a shear thickening fluid.

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#6
In reply to #5

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/25/2016 5:08 AM

Yes the viscosity and density dramatically drop after running the flow loop for like 20 minutes. So, the viscosity must have been less than the water viscosity to give pressure drop less than the Newtonian fluids do.

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#7
In reply to #6

Re: Newtonian Pressure Drop vs Non-Newtonian Prssure Drop

10/29/2016 11:23 PM

'... viscosity and density dramatically drop after running the flow loop for like 20 minutes So, the viscosity must have been less than the water viscosity to give pressure drop less than the Newtonian fluids ...'

.

Not so fast there, Sport, er, Siraj77. "Must have been" is almost certainly unwarranted. There is a good chance you are misinterpreting the data.

.

Please describe the 'flow loop' in more detail. What types of pumps are used? How is air added to the flow? Did you measure temperature? Where and when? Do you have an indication of variations in flow rate?

.

Was the mixture made with tap water? pH? Chloride? etc?

.

Temperature can have a significant effect on viscosity. Viscosity can have a significant effect on pump efficiency and thereby heat added to the fluid, so temperature. It is likely that the dramatic reduction in pressure drop after running the loop for 20 minutes had more to do with variations in viscosity due to temperature than variations in viscosity due directly to shear rate.

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