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Fluent transient analysis

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Old   January 11, 2016, 08:57
Default Fluent transient analysis
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Alex
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Hello,

I'm currently running fluent transient simulations and I want to post-process these simulations with EnSight.
Everything is working well, automatic export from FLUENT, reading data with EnSight.
But when I plot a scalar (pressure for exemple) on a part (clip plane, fluid,...) the contours are good at the beginning but from a random simulation time the scalar goes to 0 (-1.2345e-010).
The problem is also visible when I query a variable over time, the scalar is constant from a random time.

Do you have already face the same issue?

Thank you,

Alex
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Old   January 11, 2016, 12:28
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Marina Galvagni
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Hi Alex,

The value -1.2345e-10 is a special value in EnSight that means "undefined". Therefore, your variable isn't zero, but it is not defined on that part(s) at those timesteps.

So, it appears that the data is missing the value of the variable for some timesteps.

If you've exported the data in Case Gold format (Fluent gives you the option of exporting in Fluent or in Case Gold format), you can use a routine that is automatically installed with EnSight to check on the data. Open a shell / command prompt and cd into the directory where you have the data. Then, type:

ens_checker101 my_data.encas

(instead of my_data.encas, use the name of your .encas file). This will run a syntax check on the data, and will return an error message if the data syntax is corrupted.

If you still aren't sure about where the problem is, please let us know what versions of both Fluent and EnSight you're using, and which data format you are exporting to.

Hope this helps.
Best Regards,

Marina Galvagni
CEI Software Support Engineer
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Old   January 12, 2016, 04:30
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Hi Marina,

Thanks a lot for your support.

I have run your command. And the VARIABLE section failed so the Verification of the data FAILED (see attached file)
I'm using FLUENT v15.0 with EnSight 10.0.3 and now I'm testing EnSight 10.1.6 in order to see if it could help to solve my issue.
I'm using a fluent journal to export automatically data to EnSight during the transient simulation. For some simulations the verification is succesful. I'm exporting data with these commands:

file transient-export ensight-gold-transient
ENSIGHT_DYN_NAME
default-interior
interior_1
interior_2
interior_3
interior_4
interior_5



pressure
dynamic-pressure
total-pressure
density
velocity-magnitude
q
y
y
ENSIGHT_DYN_NAME
1
n

q
q

Thanks again,

Alex
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File Type: jpg Issue_ENSIGHT.JPG (64.7 KB, 11 views)
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Old   January 12, 2016, 10:41
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Alex,

There definitely is a mistake in the data format. I think you will need to contact the Fluent support and have them take a look at this, as they are the ones in charge for the Fluent-to-Case-Gold exporter, and I can't be of any help here.

As a work-around, you can export the simulation in Fluent format (.cas and .dat files) and load the data in this format in EnSight (note that the Fluent format is less efficient than the Case Gold format in EnSight, so that's why I suggest this as work around while the problem of the exporter gets fixed). Do you still have the same issue with the data in this format?

Marina
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Old   January 14, 2016, 04:11
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Hello Marina,

Thank you again for your answer!

The problem seems to be solve with FLUENT v16.2, the verification (cmd ens_checker101) is ok and the post-processing in EnSight works well!

Regards,

Alex
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