Velocity vector volume average - where to start

rclement · February 20, 2018, 08:44

Hi, I am new to OpenFoam and I am trying to model the mean air flow in the gap between the ends of two cylinders. The image below shows the plane through the centre-line of the two cylinders for the final time-step of my effort on this problem. The image is the x velocity component (left to right).

What I would like to get from this result if the volume average velocity components (Ux, Uy, Uz) for the volume between the ends of the two cylinders.

However, I'm not sure where to begin. Should this be done in OpenFoam or Paraview or on the VTK data? If anyone can point me in the right direction (preferably with examples) that would be very much appreciated.

Thanks

rclement · March 1, 2018, 05:33

I found a 3-step way of doing this in ParaView:

1. Use 'Calculation' filter to create boolean field defining points within desired radius from cylinders' axes i.e. sqrt(coordY^2 + coordZ^2) < some_radius

2. Use 'Threshold' filter to select results from previous calculation filter that are greater than 0

3. Apply Integration filter on result from the Threshold filter. You need to normalize by the cell volumes and have the result display the cell values for the data (Ux, Uy and Uz)

This is being done manually in paraFoam. If anyone knows how to do the equivalent in Openfoam, that would be appreciated

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March 1, 2018, 05:33		#2
rclement New Member R Clement Join Date: Feb 2018 Location: Edinburgh Posts: 5 Rep Power: 8	I found a 3-step way of doing this in ParaView: 1. Use 'Calculation' filter to create boolean field defining points within desired radius from cylinders' axes i.e. sqrt(coordY^2 + coordZ^2) < some_radius 2. Use 'Threshold' filter to select results from previous calculation filter that are greater than 0 3. Apply Integration filter on result from the Threshold filter. You need to normalize by the cell volumes and have the result display the cell values for the data (Ux, Uy and Uz) This is being done manually in paraFoam. If anyone knows how to do the equivalent in Openfoam, that would be appreciated