[Krao]

Dear Foam users,

Presently I am doing the post processing of the simulation as explained in the following thread One half propeller simulation with MRFSimpleFoam crashing. I have used BEMT for the propeller design. I am having 15% variation in the forces between BEMT and CFD, therefore I had planned to use paraview(with OpenFOAM 6) for post processing, by dividing the propeller blade into 10 elements, which is exactly the number of elements in my design. As a first step to compare the paraview and simpleFoam results I have calculated the forces by considering the full propeller, and the procedure is explained below.

1) Load the case using the command paraFoam
2) Select the required patch, in my case it is propeller blade
3) Filters - Extract surface
4) Filters - Generate surface normals
5) Filters - Cell data to point data
6) Calculator - Force = pressure*normals
7) Filters - Integrate variables, this generates the table from in which the result (Force) is present

After performing the steps mentioned above, the Force obtained is, Force = (0.269, 2.988, 20.063). This value is less when compared with the results from MRF simpleFoam (0.291062, 3.70328, 22.952). Are there anyone in this forum faced the similar problem. Please let me know if the above steps performed are wrong. Also, suggest me if I need to manipulate something in the script while defining the forces.

Please let me know if I required to provide more details. Thank you in advance.

Krao

[Krao]

I did the basic mistake of not multiplying the pressure with density.After multiplying the pressure with density, I got the expected values. Hope it helps future readers. If anyone find this wrong please let me know.

Krao

[Carlo_P]

Hey Krao, if you want take a look into this tutorial:
https://www.youtube.com/watch?v=J944HOj_4b0


on how calculate drag and torque with paraview.


Another suggestion (but I'm not 100% sure).
If you want to have the pressure multyply by the density, you can add #includeFunc staticPressure or #includeFunc static(p) in the end of the controlDict.


You will recevide the value of pressure*density, you can use directly on parafoam.
Try this, I'm not 100% sure.