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February 5, 2018, 04:35 |
how to calculate 'grad(UMean)' in OF-5.0?
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#1 |
New Member
sagar saroha
Join Date: Sep 2015
Posts: 11
Rep Power: 11 |
I have been using:
pisoFoam -postProcess -func "grad(U)"and it works well... but when i try using: pisoFoam -postProcess -func "grad(UMean)"for calculating mean velocity gradient - it show the following error --> FOAM Warning : functionObjects::grad grad(UMean) cannot find required object UMean of type volScalarField --> FOAM Warning : functionObjects::grad grad(UMean) cannot find required object UMean of type surfaceScalarField --> FOAM Warning : functionObjects::grad grad(UMean) cannot find required object UMean of type volVectorField --> FOAM Warning : functionObjects::grad grad(UMean) cannot find required object UMean of type surfaceVectorField --> FOAM Warning : functionObjects::grad grad(UMean) failed to execute. Please help me identify the mistake or suggest an alternate way to calculate gradient of mean velocity. Last edited by sagar_saroha; February 6, 2018 at 02:38. Reason: incomplete question |
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February 5, 2018, 08:17 |
a smart alternative patch
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#2 |
New Member
sagar saroha
Join Date: Sep 2015
Posts: 11
Rep Power: 11 |
In my attempts to solve the problem, I managed to get an alternate way of doing so...
Seemingly the problem was mainly due to the name of the file 'UMean'. I did rename the file to 'U' and then calculated its gradient using pisoFoam -postProcess -func "grad(U)"I still expect to hear from experienced users about the non-eluding way of addressing it. Last edited by sagar_saroha; February 6, 2018 at 02:38. |
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February 5, 2018, 09:18 |
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#3 |
Member
Ricky
Join Date: Jul 2014
Location: Germany
Posts: 78
Rep Power: 12 |
Hallo Sagar!
If you already have your simulation results of the case! Can you tell me, what output do you get after executing this piece of command in the terminal: Code:
postProcess -latestTime -func "grad(UMean)" or postProcess -noZero -func "grad(UMean)" Code:
pisoFoam -postProcess -noZero -func "grad(UMean)" Regards, Ricky PS: I am assuming that the UMean field exist in your time directories
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February 6, 2018, 02:36 |
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#4 | |
New Member
sagar saroha
Join Date: Sep 2015
Posts: 11
Rep Power: 11 |
Hi Ricky
Thanks a lot for the reply; both of your suggestions do work: Quote:
yeah, I had UMean field existing in the time directories. I am curious to know if it was 'zero' time folder which was causing issue or something else? |
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February 6, 2018, 04:33 |
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#5 |
Member
Ricky
Join Date: Jul 2014
Location: Germany
Posts: 78
Rep Power: 12 |
Hallo Sagar!
well your suspicion is in fact correct. It was actually the "zero" folder that was causing the error, as "UMean" field is not available at the start, rather it is created in the subsequent iterations. --> at least that's what I think Regards, Ricky
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If it is easy, then something is fishy! |
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June 2, 2020, 07:25 |
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#6 |
Member
Join Date: Apr 2018
Location: UK
Posts: 78
Rep Power: 8 |
Hello,
I know this post is a bit old but it's the only one I could find that prints a similar error message to what I'm getting. I am also using OF v5 and I introduced a functionObject in my controlDict to calculate the gradient of velocity during run-time using grad(U). The functionObject is: Code:
gradUtensor// shearStressU // originally gradientU { type grad; libs ("libfieldFunctionObjects.so"); field U; writeControl writeTime; } Code:
--> FOAM Warning : functionObjects::grad gradUtensor cannot find required object U of type volScalarField --> FOAM Warning : functionObjects::grad gradUtensor cannot find required object U of type surfaceScalarField |
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Tags |
grad(umean), openfoam 5, post procesing |
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