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Using non-Newtonian fluids in Fluent

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Old   October 17, 2000, 06:11
Default Using non-Newtonian fluids in Fluent
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Irene Fyrippi
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I've been using Fluent during the last 5 months and I get quite good results when dealing with Newtonian fluids.However,when I started testing non-Newtonian fluids(basically power-law fluids)the velocity profiles I was getting were more or less the same as for Newtonian fluids.

Has anybody got any suggestions on why this happened?

Thanks
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Old   October 18, 2000, 03:13
Default Re: Using non-Newtonian fluids in Fluent
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Rüdiger Schwarze
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I found that the non-newtonian fluids feature of FLUENT works well. Can You give some more details of Your problem?
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Old   October 18, 2000, 09:28
Default Re: Using non-Newtonian fluids in Fluent
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Irene Fyrippi
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hi.

I want to investigate a flow of non-Newtonian fluids in a straight pipe of lengh 8m and diameter of 80mm.By the time i'm changing viscosity to non-Newtonian power law,I get a message on Fluent screen saying:"Error:unbound variable".For power law index of 0.519 and consistency index of 0.0002,the velocity profile at the outlet is more or less the same as for water.Even by refining the mesh and setting a boundary layer at the inlet,I didn't get better results.

Any ideas on what's wrong?

Thanks for your reply.

Kind regards

Renata
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Old   October 18, 2000, 09:56
Default Re: Using non-Newtonian fluids in Fluent
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Rüdiger Schwarze
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What is the mean and the maximum velocity in the problem?
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Old   October 19, 2000, 04:49
Default Re: Using non-Newtonian fluids in Fluent
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Irene Fyrippi
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I 'm not using mean velocity. However, the axial velocity at the inlet varies from 0(at the wall) to 1(=Umax,at the axis).These are the values after normalising the outflow velocity profile.

As for the axial velocity,I also run different problems,starting from Uax=0.00625 m/s up to Uax=3.32 m/s.

I hope this info will help you.
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Old   October 23, 2000, 02:52
Default Re: Using non-Newtonian fluids in Fluent
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Rüdiger Schwarze
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What kind of fluid do You want to investigate? The consistency index of 0.0002 is appropriate to estimate the average viscosity of air, if You want to model water, You should use k=0.001.
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Old   October 25, 2000, 10:28
Default Re: Using non-Newtonian fluids in Fluent
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Irene Fyrippi
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I will be testing aqueous solutions of the following polymers:xanthan gum,polyacrylamide,carboxymethyl cellulose and possibly laponite. All of the above are shear-thinning non-Newtonian fluids. The values of the power-law parameters n and k were/will be obtained by matching the power law to the Cross model from the rheological data obtained from the lab.
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Old   November 13, 2000, 04:24
Default Re: Using non-Newtonian fluids in Fluent
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Rüdiger Schwarze
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Hi Irene,

have You tried out successfully other power-law parameters?
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Old   November 15, 2000, 09:08
Default Re: Using non-Newtonian fluids in Fluent
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Irene Fyrippi
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Hi

Yes,different power-law parameters have been used successfully by a friend of mine(on the same problem),but they are very different from what I want to use.So the problem really is why my parameters aren't working.Have you got any suggestions?

Thanks

Irene
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Old   June 8, 2012, 10:10
Default non-newtonial fluid in FLUENT
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Mohammed Al-Azawy is on a distinguished road
How can I use non-newtonian fluid(blood) in ANSYS FLUENT 14?
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Old   July 22, 2012, 15:53
Default non newtonian flow of blood
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viki kar
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hi

I have the same question! how is it possible to model non newtonian flow of blood in fluent 6?
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