Time history of wall Shear Stress.
 

Hi

I need a little help. I wanted to observe how the wall Shear Stress changes over time for my case. To achieve that, I execute wallShearStress utility, which creates the wallShearStress field in all the (written) time-step folders (startTime startTime + writeInterval startTime +2*writeInterval ... and so on till endTime).

Does anybody know how I can extract the 'wall' patch value of wallShearStress from each of these folders and plot them as a function of iterations/time steps? Any comments are welcome!

Hi,

I guess there can be another solution but usually I do the following:

1. Sample values of a field (in your case wallShearStress) with sample utility; it will create folders postProcessing/surfaces/* with sampled data in them
2. Use python to iterate over created folders to read values in array [time, value]
3. Use matplotlib to plot values

Surely you can substitute python and matplotlib with preferred software.

But I is your wall shear stress constant over the wall patch?

Thanks Alexey

I did not think of using Python to extract the values from the folders, so that is a start.
I have just two cells in the x direction along the wall patch. The wallShearStress does not vary so much between them.

Hi,

Actually I've recalled more convenient way of doing what you want. There's an utility probeLocations. You create probesDict in system folder of your case (you can find example in $FOAM_APP/utilities/postProcessing/sampling/probeLocations), run the utility and it will create files in postProcessing/probes with time evolution of the field at a given location.