Spatial average of viscosity

nskelly · May 23, 2019, 06:19

Hi,

I have ran some shear thinning simulations of a backward facing step in OpenFOAM and would like to calculate the spatial average of viscosity across the domain.

Is this possible to do in paraview? I know of the postSpanwiseAverage toolbox but this seems to just average the velocity.

The other alternative is to use Matlab, but I am a bit unsure how to do it in there also as it would read in cell data but the points are not uniform due to the meshing.

Any help would be great.

agustinvo · June 13, 2019, 06:09

Hi,

did you created you mesh with blockMesh? If you know python, try to use fluidfoam, and you can load the cells in the order they where created (with blockMesh is more or less evident in function or the order of your blocks), and perform the average after some matrix manipulation.

yambanshee · June 19, 2019, 06:31

In parafoam, you can use the filter 'integrate variables' with the option 'divide cell data by volume' turned on. This will open a spreadsheat view up, and by selecting the attribute 'cell values' in the drop down menu, you can get all your properties spatially averaged.

If you would like to do it in a software like matlab, i would recommend using the filter meshQuality and setting Hex/quad/etc... to volume, and then saving that filter as a csv. This will give you all your fields per cell, along with that cell's volume.

In 1d, a simlar process can be used with the filter 'arcLength', which I use to create circumferentially averaged data with varying heights.

Regards!

May 23, 2019, 06:19	Spatial average of viscosity	#1
nskelly Member Nat K Join Date: Oct 2017 Posts: 68 Rep Power: 9	Hi, I have ran some shear thinning simulations of a backward facing step in OpenFOAM and would like to calculate the spatial average of viscosity across the domain. Is this possible to do in paraview? I know of the postSpanwiseAverage toolbox but this seems to just average the velocity. The other alternative is to use Matlab, but I am a bit unsure how to do it in there also as it would read in cell data but the points are not uniform due to the meshing. Any help would be great.

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June 13, 2019, 06:09		#2
agustinvo Senior Member Agustín Villa Join Date: Apr 2013 Location: Alcorcón Posts: 314 Rep Power: 16	Hi, did you created you mesh with blockMesh? If you know python, try to use fluidfoam, and you can load the cells in the order they where created (with blockMesh is more or less evident in function or the order of your blocks), and perform the average after some matrix manipulation.

June 19, 2019, 06:31		#3
yambanshee Senior Member Zander Meiring Join Date: Jul 2018 Posts: 125 Rep Power: 8	In parafoam, you can use the filter 'integrate variables' with the option 'divide cell data by volume' turned on. This will open a spreadsheat view up, and by selecting the attribute 'cell values' in the drop down menu, you can get all your properties spatially averaged. If you would like to do it in a software like matlab, i would recommend using the filter meshQuality and setting Hex/quad/etc... to volume, and then saving that filter as a csv. This will give you all your fields per cell, along with that cell's volume. In 1d, a simlar process can be used with the filter 'arcLength', which I use to create circumferentially averaged data with varying heights. Regards!