# crosspowerlaw nu0 and nuinf, which is bigger？

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January 6, 2013, 05:17
crosspowerlaw nu0 and nuinf, which is bigger？
#1
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Dongyue Li
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return (nu0_ - nuInf_)/(scalar(1) + pow(m_*strainRate(), n_)) + nuInf_;

According to this, nu0 is the kinematic viscosity when the stress rate tends to zero. and nuinf is the one that the stress rate tends to infinate.

Quote:
 transportModel CrossPowerLaw; CrossPowerLawCoeffs { nu0 nu0 [ 0 2 -1 0 0 0 0 ] 0.01; nuInf nuInf [ 0 2 -1 0 0 0 0 ] 10; m m [ 0 0 1 0 0 0 0 ] 0.4; n n [ 0 0 0 0 0 0 0 ] 3; }
Should it be nu0 bigger than nuinf?

but in the tutorial case is opposite.

Last edited by sharonyue; January 6, 2013 at 05:53.

 January 6, 2013, 05:59 #2 Senior Member   Dongyue Li Join Date: Jun 2012 Location: Torino, Italy Posts: 742 Rep Power: 9 Maybe I figure it out, in this case n>3 which indicate its Shear thickening. I will validate it soon.

 January 7, 2013, 00:59 #3 Senior Member   Tushar Chourushi Join Date: Jul 2009 Location: IIT-Indore, India Posts: 319 Blog Entries: 1 Rep Power: 10 nu_0 is lesser in this case then the nu_inf, as n >1.

January 17, 2013, 09:35
#4
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Dongyue Li
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Quote:
 Originally Posted by Tushar_Mtechcfd nu_0 is lesser in this case then the nu_inf, as n >1.
Hi Tushar
Code:
`m m [ 0 0 1 0 0 0 0 ] 0.4;`
Does this m mean consistency index? but consistency index's dimension is not this. I am confused.

March 7, 2013, 03:49
#5
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Dongyue Li
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Quote:
 Originally Posted by sharonyue Hi Tushar Code: `m m [ 0 0 1 0 0 0 0 ] 0.4;` Does this m mean consistency index? but consistency index's dimension is not this. I am confused.
Does anybody know whats the meaning of m?

April 1, 2013, 01:29
#6
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Tushar Chourushi
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Quote:
 Originally Posted by sharonyue Does anybody know whats the meaning of m?

m actually is a natural time.
I think you are trying to co-relate with powerlaw but this isn't correct. The mentioned model is CrossPowerLaw and it is different from PowerLaw. Try looking some more literature on it.

Best of luck.

April 1, 2013, 03:44
#7
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Dongyue Li
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Quote:
 Originally Posted by Tushar@cfd m actually is a natural time. I think you are trying to co-relate with powerlaw but this isn't correct. The mentioned model is CrossPowerLaw and it is different from PowerLaw. Try looking some more literature on it. Best of luck.
Woo,Tushar,

That really helps me alot.I check it out and find its natural time from one paper.

But in another paper it said this:

Why is it so different?

Thanks a lot!

Regards,
Attached Images
 1.jpg (73.8 KB, 27 views) 2.jpg (65.5 KB, 31 views)

April 1, 2013, 08:13
#8
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Tushar Chourushi
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Quote:
 Originally Posted by sharonyue Woo,Tushar, That really helps me alot.I check it out and find its natural time from one paper. But in another paper it said this: Why is it so different? Thanks a lot! Regards,
Well sharonyue, nice question.
I think, this may be because we are trying to match a range as mentioned in the 2.jpg
It's just a guess, I am also not sure.

Do let us know if you happen to find the answer.

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