[NotOverUnderated]

Hello,

I have a small issue with the sign of the total force acting on an object. I have used OpenFOAM to compute the forces. I have also computed the wall Shear Stress field on that surface.

I am trying to compute the same total force but in paraview by integrating the following:

-rho*p*Normals + rho*wallShearStress

I get the exact same result compared to the one computed by OpenFOAM except the sign is the opposite.



so in order to get the same results as OpenFOAM I had to do:

rho*p*Normals - rho*wallShearStress

Could someone please clarify why the sign is inversed? because as far as I understand the minus should appear in the first term not the second.

I am grateful to your help

[NotOverUnderated]

Well done Paraview well done!

It turns out that Paraview inverses the surface normals! I had to flip them and use the "correct formula":

-rho*p*Normals + rho*wallShearStress

And then integrate that over the surface to get the exact same result compared to OpenFOAM results.

(See the attached image to see the flipped normals )