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Old   June 23, 2013, 21:17
Default Herschel-Bulkley model
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Dongyue Li
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Hi,

The Herschel-Bulkley (HB) non-Newtonian viscosity model in OpenFOAM allows for a transition to Newtonian behavior when the shear rate is very low, thereby eliminating the undesirable discontinuity in the function at zero stress..........More details see here
Herschel-Bulkley non-Newtonian viscosity model has term with sign error

my problem is in the last post, Thank you all!
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Old   June 24, 2013, 00:38
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Tushar Chourushi
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Quote:
Originally Posted by sharonyue View Post
Hi,

The Herschel-Bulkley (HB) non-Newtonian viscosity model in OpenFOAM allows for a transition to Newtonian behavior when the shear rate is very low, thereby eliminating the undesirable discontinuity in the function at zero stress..........More details see here
Herschel-Bulkley non-Newtonian viscosity model has term with sign error

my problem is in the last post, Thank you all!
Good work.
Do you think any problem with the Model?

Actually, the model seems to be correct in the new versions of OF. Earlier it had problem as mentioned in the post but later it was corrected.

Last edited by Tushar@cfd; June 24, 2013 at 02:29.
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Old   June 25, 2013, 05:30
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Quote:
Originally Posted by Tushar@cfd View Post
Good work.
Do you think any problem with the Model?

Actually, the model seems to be correct in the new versions of OF. Earlier it had problem as mentioned in the post but later it was corrected.
Hi Tushar,

I dont know thats thread's mean, is there any difference between tau0 and tauy?

Thanks
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Old   June 26, 2013, 01:19
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Quote:
Originally Posted by sharonyue View Post
Hi Tushar,

I dont know thats thread's mean, is there any difference between tau0 and tauy?

Thanks
Hello sharonyue,

May be, the author might have described in that manner.

As, far as I know:
when shear-rate = 0 then tauyx < tau0
Later with, shear-rate > 0, tauyx > tau0, and we have the model equation for the same.

Correct me, if I am wrong..


Last edited by Tushar@cfd; June 26, 2013 at 03:49.
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Old   June 26, 2013, 03:49
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Herschel-Bulkley non-Newtonian viscosity model has term with sign error

tauy=tau0 in the present model when shear-rate = 0 (low shear rate)
I think author did found some relationship based on which he concluded tauy is not the same.

If you happen to see the fluent code,
It also contains same equation for the model just like the OpenFOAM code.

Anyways, this one seems to be a good post for debate.
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Old   July 8, 2013, 23:36
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Quote:
Originally Posted by Tushar@cfd View Post
Herschel-Bulkley non-Newtonian viscosity model has term with sign error

tauy=tau0 in the present model when shear-rate = 0 (low shear rate)
I think author did found some relationship based on which he concluded tauy is not the same.

If you happen to see the fluent code,
It also contains same equation for the model just like the OpenFOAM code.

Anyways, this one seems to be a good post for debate.
Sorry, very late.

But Im still confused about this tao0 and tauy, in HB model, there is only one taoy. Can you explain it more? With a image is the best. Thanks very much.
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