Forum: OpenFOAM
July 17, 2014, 10:28
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Replies: 70
Views: 28,239
Well, this was a concept we were talking about...
Well, this was a concept we were talking about all the time. The viscous term includes both normal and in-plane components, but the pressure term only contains normal component. So if anyone would be...
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Forum: OpenFOAM
July 16, 2014, 16:51
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Replies: 70
Views: 28,239
Hi,
Reasonably, the total traction force...
Hi,
Reasonably, the total traction force would be originated from the total stress tensor consisted of both pressure and viscous terms; however, it has a typo and needs to be modified like this:
...
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Forum: OpenFOAM
April 10, 2013, 18:18
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
April 10, 2013, 17:59
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
April 6, 2013, 07:17
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Replies: 70
Views: 28,239
No, this is not correct! We are talking about...
No, this is not correct! We are talking about deviation tensor (T) not the whole stress tensor. The pressure is not a part of deviation tensor. The normal component is originated from the strain rate...
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Forum: OpenFOAM
April 5, 2013, 16:16
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
April 5, 2013, 14:11
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Replies: 70
Views: 28,239
The real wall shear stress would be lower since...
The real wall shear stress would be lower since it's just one of the component of the wall traction. (The wall traction has 2 perpendicular components, the real wall shear stress and the normal one)...
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Forum: OpenFOAM
April 5, 2013, 10:51
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Replies: 70
Views: 28,239
Dear Albert,
That's my question too! :)
...
Dear Albert,
That's my question too! :)
Regarding my own experience, and as a part my master thesis, I found around 10% deviation between these 2 relations for my case, which was a...
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Forum: OpenFOAM
April 4, 2013, 05:42
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Replies: 70
Views: 28,239
Hi,
None of the implemented statements are...
Hi,
None of the implemented statements are real wall shear stress but in many cases their differences are really negligible; i.e., it depends on the wall curvature and the velocity gradients.
In...
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Forum: OpenFOAM
March 15, 2013, 12:38
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Replies: 70
Views: 28,239
Reasonably, it's consisted of laminar and...
Reasonably, it's consisted of laminar and turbulent parts; you can find that from the solver code and regarded libraries.
Dear Mojtaba,
This is not correct to put the "tau" file to "0" folder!...
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Forum: OpenFOAM
March 15, 2013, 09:45
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
August 15, 2012, 15:43
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
August 15, 2012, 11:47
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Replies: 70
Views: 28,239
The resolution is not the concern but the mesh...
The resolution is not the concern but the mesh grading is. If you have equal-size faces, you'll achieve the same result. But generally, your formulation doesn't lead to the average value physically...
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Forum: OpenFOAM
August 15, 2012, 09:55
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
August 14, 2012, 07:26
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
August 13, 2012, 15:37
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Replies: 70
Views: 28,239
Oh, sorry about previous post, that was a forum...
Oh, sorry about previous post, that was a forum conflict! :o
But in openFoam it seems that the original utility compute wall traction instead of wall shear stress and I posted the revised form you...
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Forum: OpenFOAM
August 13, 2012, 10:17
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Replies: 70
Views: 28,239
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Forum: OpenFOAM
September 23, 2011, 10:15
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Replies: 70
Views: 28,239
Dear Guifan,
First of all, note that this...
Dear Guifan,
First of all, note that this relation for shear stress we discussed about is valid just for incompressible flow; for compressible cases, another term should be added.
As you know, in...
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Forum: OpenFOAM
September 19, 2011, 23:14
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Replies: 70
Views: 28,239
Dear Guifan,
Your definition is wrong; here,...
Dear Guifan,
Your definition is wrong; here, viscosity is a function of shear rate, it's not a multiplication term! :eek:
T=2 \eta (\gamma\dot{} ) D
The differences maybe due to coarse grid near...
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Forum: OpenFOAM
September 18, 2011, 09:42
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Replies: 70
Views: 28,239
There are few errors in this part of code: ...
There are few errors in this part of code:
First of all: I'm not sure that inner product is overloaded for 2 variables which one of them is scalar and another is vector, so it's better to use:...
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Forum: OpenFOAM
September 17, 2011, 08:37
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Replies: 70
Views: 28,239
Dear Guifan,
T is stress tensor and n is...
Dear Guifan,
T is stress tensor and n is unit normal vector, according to openFOAM definitions:
n=-mesh.Sf().boundaryField()[patchi] / mesh.magSf().boundaryField()[patchi]
and, ...
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Forum: OpenFOAM
September 16, 2011, 06:08
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Replies: 70
Views: 28,239
Dear Guifan,
In many solvers such as FLUENT...
Dear Guifan,
In many solvers such as FLUENT and OpenFOAM wall traction is considered as wall shear stress and I don't know why!
If we assume T as stress tensor and n as unit normal vector of...
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Forum: OpenFOAM
September 16, 2011, 03:38
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Replies: 70
Views: 28,239
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