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Monitoring Torque on rotating body in MRFSimpleFoam |
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July 26, 2011, 03:17 |
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#21 |
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tnx Linnemann, your suggestion is the best you are right
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February 21, 2012, 16:15 |
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#22 |
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Elh. A2. BAH
Join Date: Jan 2012
Posts: 64
Rep Power: 14 |
Hello Niels,
I am trying to use this forces function to extract moment. But the output is all the time zero. would you have an idea of what I am doing wrong? Here is a sample output: ----------------------- forces output: forces(pressure, viscous)((0 0 0) (0 0 0)) moment(pressure, viscous)((0 0 0) (0 0 0)) -------------------- Basically what I am trying to do is to get the moment and calculate the rpm such that the next iteration has this rpm. Thank you for your time. Best regards. |
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February 21, 2012, 17:35 |
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#23 |
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Elh. A2. BAH
Join Date: Jan 2012
Posts: 64
Rep Power: 14 |
Hello Niels and anyone reading this post and the previous one,
Please, disregard the fact about the outputs being all zeros. I made a stupid mistake by not mis-spelling on of my patches. Yet if one has a lead on the second part, any suggestion is welcome. My best regards. |
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March 1, 2012, 17:52 |
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#24 |
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Elh. A2. BAH
Join Date: Jan 2012
Posts: 64
Rep Power: 14 |
Dear all,
Is there a way to choose the output format. For instance, in file forces/0/forces.dat, every thing is output in one line for each time step. How should proceed to have this output in column. e.g., Fpx = .... Fpy = .... Fpz = .... etc. I want to do this because I need to read some of the components and do some calculations the result od which I feed to the next iteration. Thank you all for your time. |
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March 7, 2012, 13:48 |
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#25 |
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Gabriele
Join Date: Feb 2012
Posts: 6
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Hi
There is a Python script in this thread: http://www.cfd-online.com/Forums/ope...-brackets.html Regards |
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March 8, 2012, 00:08 |
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#26 |
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Elh. A2. BAH
Join Date: Jan 2012
Posts: 64
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Thanks Gabriele for answering,
I wrote a dummy script of my own. Best regards. |
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July 2, 2012, 05:43 |
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#27 |
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prasanth
Join Date: Jul 2010
Location: Chennai, India
Posts: 17
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Hello All,
Can any body face the issue with torque value in OpenFOAM? Currently I am using OpenFOAM-2.1.1. Torque value is not matching with any of the other commercial packages like CCM+ or fluent etc. In CCM+ there is option called wall rotation set to zero for some patches. Is it same as non rotating Patches in OpenFOAM. If I am giving patch names under non rotating patches, velocity is showing zero on those patches. According to settings, it is correct only. But There is a Rotating Zone. So, there should be some relative velocity on those patches. I am thinking, this may be the reason, why OF torque value is not matching. May be my thinking can be wrong. Can any body help me on this. |
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July 2, 2012, 05:44 |
Torque value in OpenFOAM
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#28 |
New Member
prasanth
Join Date: Jul 2010
Location: Chennai, India
Posts: 17
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Hello All,
Can any body face the issue with torque value in OpenFOAM? Currently I am using OpenFOAM-2.1.1. Torque value is not matching with any of the other commercial packages like CCM+ or fluent etc. In CCM+ there is option called wall rotation set to zero for some patches. Is it same as non rotating Patches in OpenFOAM. If I am giving patch names under non rotating patches, velocity is showing zero on those patches. According to settings, it is correct only. But There is a Rotating Zone. So, there should be some relative velocity on those patches. I am thinking, this may be the reason, why OF torque value is not matching. May be my thinking can be wrong. Can any body help me on this. |
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February 6, 2013, 18:16 |
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#29 | |
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Pengchuan Wang
Join Date: Nov 2012
Location: Michigan USA
Posts: 58
Rep Power: 14 |
Hi Linnemann,
I want to know the torques on two patches. So I added two names. However, OpenFOAM only gives me the sum of the two torques. Can you help me with this? Thank you very much. Pengchuan Quote:
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February 7, 2013, 09:11 |
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#30 |
Senior Member
Olivier
Join Date: Jun 2009
Location: France, grenoble
Posts: 272
Rep Power: 18 |
hello,
I guess you already have find the solution, but just in case : Code:
functions ( forces_patch1 { type forces; ... patches (patch1); ... } forces_patch2 { type forces; ... patches(patch2); ... } ) olivier |
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February 7, 2013, 10:33 |
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#31 |
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Pengchuan Wang
Join Date: Nov 2012
Location: Michigan USA
Posts: 58
Rep Power: 14 |
Hi Olivier,
Thank you very much. It helps me a lot. I have another question. Do you know how to calculate the flow rate on one surface. It seems that it is very complex to do that. Is that right?Thank you again. Pengchuan |
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February 7, 2013, 10:59 |
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#32 |
Senior Member
Olivier
Join Date: Jun 2009
Location: France, grenoble
Posts: 272
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Hello Pengchuan,
If you are using OF version <= 2.0, take a look at http://openfoamwiki.net/index.php/Contrib_simpleFunctionObjects. If this is not the case, take a look at swak4foam. regards, olivier |
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March 19, 2013, 20:55 |
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#33 |
Member
Pengchuan Wang
Join Date: Nov 2012
Location: Michigan USA
Posts: 58
Rep Power: 14 |
Hi Olivier,
Now I use SRFSimplefoam to do some simulations. In SRFsimpleFoam, there is no U file, only Urel. I modify the code to Pname P; Uname Urel. Unfortunately, it didn't work. Can you give me a hand on this? |
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September 9, 2013, 22:34 |
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#34 |
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QuocThien
Join Date: Apr 2013
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I think just waiting for some writing steps and modify controdict with Uabs.
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November 12, 2013, 06:58 |
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#35 |
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Mads Reck
Join Date: Aug 2009
Location: Copenhagen, Denmark
Posts: 177
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Hi guys,
I use Urel (this is the only one that works) in the force section of controlDict but I get very wrong torque. Any suggestions here? Or anyone having issues with SRFSimpleFoam and torque/forces. Mads
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November 18, 2013, 09:01 |
Calculating Forces at SRFSimpleFoam
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#36 |
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Tobias Adam
Join Date: Oct 2013
Location: Siegen
Posts: 55
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I have the same problem as Pengchuan. I use SRFSimpleFoam and donīt get the right name for U. I even tried Urel but it didnīt work!
Code:
forces { type forces; functionObjectLibs ("libforces.so"); outputControl timeStep; outputInterval 20; patches (BLADE); pname p; Uname Uabs; // or Urel, or U, nothing worked... rhoName rhoInf; log true; rhoInf 1.205; CofR (0 0 0); liftDir (0 0 1); dragDir (1 0 0); I get the following error message: Code:
FOAM Warning : From function void forces::read(const dictionary&) in file forces/forces.C at line 449 Could not find U, p in database. De-activating forces. I donīt understand why Urel does not work. I use a second Run-time Post-processing library called Probes which works perfectly with Urel. Code:
probes { type probes; functionObjectLibs ("libsampling.so"); probeLocations ((0 0 -0.7) (1 0 -0.1) (1 0 0.1) (1.55 0 0)); fields ( Urel p ); Thank you very much for your help. Best regards Tobias |
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November 18, 2013, 09:47 |
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#37 |
Senior Member
Aurelien Thinat
Join Date: Jul 2010
Posts: 165
Rep Power: 16 |
Hi Tobias,
I have never used SRFSimpleFoam, but there are some similar problem other solvers. If there is no file U in your solver : it's possible that the force calculating utility use a hard coded name of the velocity file. If you can compile on your machine, you can juste create a field U defined by U = Uabs. And then use the force function with this new field. It should work. You may have to do the same with the pressure if there is no "p" field. |
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November 19, 2013, 15:48 |
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#38 |
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Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
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Hi dear Tobias,
I haven't worked with this solver,what are the fields it uses?
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November 20, 2013, 06:46 |
Problem solved
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#39 |
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Tobias Adam
Join Date: Oct 2013
Location: Siegen
Posts: 55
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Thank you very much for your help!
The problem is resolved as I changed Uname Urel; to UName Urel; I found the problem, after trying all different controll dict entries listed in the different threads for this problem (also on other websites). Many posts include this error that only leads to problems if your velocity-field is not named "U". @ Aurelien: This seems to be easier than craeting the new U field ;-). Nevertheless thank you very much for your help @ Eshan: As far as I understood the question, it uses Urel for the data output in the output-file from the backround process and from this it generates the Folder Urel and Uabs in the time directory. The rest is similar to SimpleFoam :-) best regards Tobias :-) |
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November 7, 2018, 19:12 |
Torque
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#40 |
New Member
José Yovany Galindo Díaz.
Join Date: Jun 2016
Posts: 2
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Hi Friends, Somebody can compilate the files of calculateTorque?
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