Calculated Drag Differences Paraview vs OpenFoam Output
 

Hi guys,

just want to ask for comments:


Drag Coefficient Output @ OpenFoam ControlDict -> 2.83 (like literature)
Paraview PostProcessing Calculation -> 2.49....


These are my paraviewsteps in short:


1)Extracted Surface
2)Generate Surface Normals
3)Calculated:
cp = normals*p; ->Pressure Drag
cf=normals*mu*wallGradU_y -> Friction Drag
4) Build Integral Drag=(cp_X+cf_X)*3.14156 (for Aref=1) equals in 2.49


Did I miss something?

Ok, this is just a guess from my side:

Could be the differences caused by derivation error while building dUdY of parafoam?

I am still not sure about this topic, has got anyone any idea? Is there something wrong in my workflow?

My reference Area Aref is set to 1 in controldict and my density rho to 1.2.
Is paraFoam normalizing the data in strange way?

Hi,

Did you find the solution? I also have some difference about drag calculations like you. I use the same workflow....

Best regards,
Ye

You might try to evaluate the sensitivity of forces to angle in surface normals.

Regards,
Hannes

friction drag
 

Hi all,

isn't the difference due to the friction drag (which you don't take into account when using only the pressure in paraview)?

Regards,

Wouter.