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-   -   How to determine maximum's location on patch (http://www.cfd-online.com/Forums/openfoam-post-processing/104340-how-determine-maximums-location-patch.html)

 vigges July 7, 2012 11:27

How to determine maximum's location on patch

Hi Foamers,

my simulation is running smoothly but now, I'm facing the next problem.
I need to find the maximum Nusselt number on my wall patch and its location, so that my further calculations can be executed.

I thought about hacking something into the patchAverage utility, in order to get the average Nusselt number and the maximum's location at the same time. Unfortunately, I have no clue how to do that.

Do you have any ideas?
Victor

 Gwenael July 10, 2012 03:36

Did you look into foamCalc ?

 vigges July 10, 2012 03:48

Yes, I did. But afaik, it's not capable of determining the maximum value on a patch or its exact location on the patch.
I'm sure there is a solution but it would most likely involve programming in C... Let's say that is not my strong suit :rolleyes:

 gschaider July 10, 2012 05:53

Quote:
 Originally Posted by vigges (Post 370581) Yes, I did. But afaik, it's not capable of determining the maximum value on a patch or its exact location on the patch. I'm sure there is a solution but it would most likely involve programming in C... Let's say that is not my strong suit :rolleyes:
Recent versions of swak4Foam have a function maxPosition that gives you the location of the maximum on a patch. So something like (I'm doing this from memory)
Code:

```functions {     extremeP {       type swakExpression;       valueType patch;       patchName wall;       verbose true;       expression "p";       accumulations (min max);     }     maxPPosition {       \$extremeP;       expression "maxPosition(p)";       accumulations (average);     }     minPPosition {       \$maxPPosition;       expression "minPosition(p)";     }      }```
would give you minimum and maximum of p as well as their positions on the patch during the simulation.

Advantage: you don't have to program C++

 vigges July 10, 2012 05:58

Bernhard, thanks a lot!!
I'm going to look into that.

 vigges July 10, 2012 08:30

Works perfectly :-)

Let's assume that only the final time step's max location is needed. Is it feasible to only export this value/location to a file?

 gschaider July 10, 2012 09:20

Quote:
 Originally Posted by vigges (Post 370635) Works perfectly :-) Let's assume that only the final time step's max location is needed. Is it feasible to only export this value/location to a file?
funkyDoCalc can be used to specify calculations in a file and execute them on saved data.

@file: there should be some directories named swakExpression_foo there with the data (not 100% sure whether funkyDoCalc creates them)

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