[eRzBeNgEl]

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?

[eRzBeNgEl]

Ok, this is just a guess from my side:

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

[eRzBeNgEl]

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?

[kiddmax]

Hi,

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

Best regards,
Ye

[Hannes_Kiel]

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

Regards,
Hannes

[wouterremmerie]

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.