[unilord]

Hey everyone.

As a part of my Master's Thesis, I am performing a steady state MRF analysis in OpenFOAM V11. I want to compare the CFD data I retrieved with the experimental one on the paper. They have these plots of tangential and axial relative velocities and I don't know how I can obtain these values from openfoam. I know this has to do with the velocities triangles, but I don't know how I can perform this calculation:

- c = u + w, where c is absolute velocity, u is circumferencial velocity and w is relative velocity.

- now I need w_r and w_theta. How can I convert these in openfoam? Or maybe apply a formula in paraview calculator? I saw this function called fieldCoordinateSystemTransform, but I can't manage to use it. Should I put it in the control dict? Or create a file for it in the system folder?
Preferably I would like to perform these transformations as a postprocessing and not in-run process, since I already have the simulations.

Thank you very much,
Pedro Gouveia

[unilord]

Originally Posted by unilord

Hey everyone.

As a part of my Master's Thesis, I am performing a steady state MRF analysis in OpenFOAM V11. I want to compare the CFD data I retrieved with the experimental one on the paper. They have these plots of tangential and axial relative velocities and I don't know how I can obtain these values from openfoam. I know this has to do with the velocities triangles, but I don't know how I can perform this calculation:

- c = u + w, where c is absolute velocity, u is circumferencial velocity and w is relative velocity.

- now I need w_r and w_theta. How can I convert these in openfoam? Or maybe apply a formula in paraview calculator? I saw this function called fieldCoordinateSystemTransform, but I can't manage to use it. Should I put it in the control dict? Or create a file for it in the system folder?
Preferably I would like to perform these transformations as a postprocessing and not in-run process, since I already have the simulations.

Thank you very much,
Pedro Gouveia

Hey guys,

I just found out how to get the cylindrical velocities, at least for incompressible Fluid, in OpenFOAM v11.

I don't know if it's the most correct way, but it's the only one I discovered. Put this line of code in the control dict, in the functions part:

#includeFunc fieldAverage(cylindrical(U))

And you run the analysis again, even with the final time step. (t_f) Before it calculates the time step (t_f+1), it will calculate the speed in cylindrical polar coordinates, and will write to the directory corresponding to the final time step. Then just open paraview and there is a "cylindrical(U)" property, with components x,y,z where x=r, y=theta and z=z