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July 16, 2014, 13:56 |
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#61 |
New Member
Nara Shikamaru
Join Date: Apr 2012
Posts: 22
Rep Power: 14 |
Thanks Amir for the formulation. Having taken solid mech courses I was also skeptical about the traction vector that was being calculated. I see that you are not active anymore in this forum, but big thanks for the helpful posts.
I am was working on generating the traction on the interface between two incompressible immiscible fluids (VOF formulation). I am almost done with that. The only part I have doubt about is the stress tensor term being used in this formulation - Should the viscous stress tensor be used for calculating the Traction vector? This is what I would do if I was doing solids or, The total stress tensor including the pressure term should be used? Last edited by shikamaru; July 16, 2014 at 20:21. Reason: [Typo in equation] |
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July 16, 2014, 16:51 |
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#62 |
Senior Member
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Quote:
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: Bests,
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Amir |
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July 16, 2014, 20:21 |
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#63 |
New Member
Nara Shikamaru
Join Date: Apr 2012
Posts: 22
Rep Power: 14 |
Thanks for catching the typo, fixed.
Last edited by shikamaru; July 17, 2014 at 00:55. |
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July 17, 2014, 10:16 |
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#64 |
New Member
Nara Shikamaru
Join Date: Apr 2012
Posts: 22
Rep Power: 14 |
Since pressure always acts normal to the surface, if anyone only wants the shear stress the pressure term is not needed. However, in my case I am calculating both normal and shear stress on a curved surface. So, I need the pressure term in my calculation.
Please correct me if I am wrong. |
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July 17, 2014, 10:28 |
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#65 | |
Senior Member
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Quote:
Bests,
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Amir |
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August 9, 2014, 10:07 |
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#66 |
New Member
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I wrote a post processing utility myWallShearStress according to this thread.
And thanks @Amir a lot. My utility is general, suitable for incompressible and compressible flows using RAS or LES turbulence models. |
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August 17, 2014, 11:56 |
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#67 |
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Anastasios Stampoultzoglou
Join Date: May 2014
Posts: 21
Rep Power: 12 |
Hi all,
I am a new user on openfoam . I read your posts and it was very useful. I would like to ask you which method the utility "wallShearStress" use (for example log law method or momentum method or Reynolds stress method, etc. ) Thank you very much |
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September 9, 2014, 12:34 |
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#68 | |
New Member
Daniel
Join Date: Nov 2012
Location: Glasgow, Scotland
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Quote:
Regards |
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September 13, 2014, 06:25 |
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#69 | |||||
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
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Greetings to all!
This has become a rather long and somewhat confusing thread, but unfortunately I will only be able to try and clarify Tasos' question: Quote:
Quote:
Quote:
Quote:
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Best regards, Bruno
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September 13, 2014, 09:55 |
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#70 |
New Member
Anastasios Stampoultzoglou
Join Date: May 2014
Posts: 21
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Mr Bruno thank you very very much, your help is priceless.
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December 9, 2015, 04:49 |
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#71 |
New Member
LU
Join Date: Oct 2015
Posts: 11
Rep Power: 11 |
Hello Amir
could you tell me why n=-mesh.Sf().boundaryField()[patchi] / mesh.magSf().boundaryField()[patchi] there is a minus "-" here And I also check the code in Openfoam for the forces calculation,there also calculate the viscous force which is the also wall shear stress but in the utility ,the code is: sfb[patchI]&devrhoReffb[patch] do you think there are the same? Best regards! |
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