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-   -   Python Scripting - basic help (http://www.cfd-online.com/Forums/openfoam-post-processing/90613-python-scripting-basic-help.html)

atareen64 July 15, 2011 13:14

Python Scripting - basic help
 
Hello all,

I'm trying to analyze the boundary layer growth of a fluid near a wall in a simulation that I did with openfoam. The way I'm do that is that I take cross-sectional cuts of the velocity profile and plot the 2d data and look at the 99% value of velocity by eye and record the value.

This is a very inefficient way of doing it, and ideally I'd like to have a script that does that for me automatically. Writing python, C++ or Java programs isn't a problem for me, I just need to know how or where I can get started.
How would I get started doing something like this? Any help, pointers or suggestions are welcome.

Regards,
Ammar.

gwierink July 16, 2011 03:12

Hi Ammar,

You mentioned you're familiar with python, so PyFoam is a nice place to start looking around.

atareen64 July 17, 2011 21:37

Hi Gijs,

I did look at pyFoam briefly and it seems like a great tool. However I was doing some reading and stumbled upon the sample utility: shouldn't I be able to do this boundary layer analysis just by using the sample utility?
Do you think that's true? I'll try it today and repost.

-Ammar.

matejfor July 18, 2011 02:38

Hi,
I think what you can do is to use the sample utility or even the approach you mentioned at the start and add same C++ to do exactly what you want. you will find these in: $FOAM/applications/utilities/postProcessing/ dir.

matej

gschaider July 18, 2011 09:39

Quote:

Originally Posted by atareen64 (Post 316401)
Hi Gijs,

I did look at pyFoam briefly and it seems like a great tool. However I was doing some reading and stumbled upon the sample utility: shouldn't I be able to do this boundary layer analysis just by using the sample utility?
Do you think that's true? I'll try it today and repost.

-Ammar.

For getting the values you want the sample utilitiy is definitely the tool of choice. But for comparing the results of the different runs PyFoam may help you. Have a look at the pyFoamSamplePlot.py-utility. It allows you to quickly generate the gnuplot-commands to visualize the sample-data. Since the last version it also has the possibility to compare the current case to a reference case, write the data to a format Excel (or others) understand (CSV) and compare the solutions using some simple metrics.

I'm afraid "pyFoamSamplePlot.py --help" is all the documentation you're going to get, but it shouldn't be too hard to figure out how to get all this

Bernhard


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