[Claudio]

Hi,

I want to compute the total forces across multiple patches. I am running a rectangular sloshing tank where each of the 4 walls is its own patch (LeftWall, RightWall, TopWall, BottomWall).
I tried to use the same script in controlDict that I use when the 4 walls form one single patch, but I am not sure that I get the right results.

Here's my controlDict:

    forces
    {
        type forces;
        functionObjectLibs ("libforces.so"); //Lib to load
        patches (TopWall, BottomWall, LeftWall, RightWall); // change to your patch name
        rhoInf 1000.; //Reference density for fluid
//        rhoName rhoInf;
        rhoName rho;
        pName p;
        UName U;
        CofR (0 0 0); //Origin for moment calculations
        outputControl  outputTime;
        outputInterval 0.108;
    }

Any suggestion on what might be wrong?

Thanks.

[Claudio]

Found the answer in a pre-processing thread:

    forces     
{         type forces;
         functionObjectLibs ("libforces.so"); //Lib to load
         patches (TopWall BottomWall LeftWall RightWall); // change to your patch name
         rhoInf 1000.; //Reference density for fluid
         rhoName rho;
         pName p;
         UName U;
         CofR (0 0 0); //Origin for moment calculations
         outputControl  outputTime;
         outputInterval 0.108;     }

No commas in the list of the patches names.

[pechwang]

Hi Claudio,

I'm new to OpenFOAM. And my research is about flow between two plates, one is stationary and one is rotating. I want to know the torques both on the topwall and the bottomwall. However, when I added two patch names, OpenFOAM only gives me the difference between these two torques. Can you help me with this? Thank you.

Originally Posted by Claudio

Found the answer in a pre-processing thread:

    forces     
{         type forces;
         functionObjectLibs ("libforces.so"); //Lib to load
         patches (TopWall BottomWall LeftWall RightWall); // change to your patch name
         rhoInf 1000.; //Reference density for fluid
         rhoName rho;
         pName p;
         UName U;
         CofR (0 0 0); //Origin for moment calculations
         outputControl  outputTime;
         outputInterval 0.108;     }

No commas in the list of the patches names.

[Bashar]

Originally Posted by pechwang

Hi Claudio,

I'm new to OpenFOAM. And my research is about flow between two plates, one is stationary and one is rotating. I want to know the torques both on the topwall and the bottomwall. However, when I added two patch names, OpenFOAM only gives me the difference between these two torques. Can you help me with this? Thank you.

Hi , did you manage to solve this isuues?

[pechwang]

Hi Hassan,

Yes, the right way is that you need to calculate the torque on each plate separately. So the right format should be:

functions
(
force1
{
type forces;
functionObJectLibs ("libfroces.so")
outputControl timeStep;
outputInterval 10;
patches (patch_name)
pname p;
uname U;
rhoName rhoInf;
log true;
rhoInf XXX;
CofR (0 0 0);
}
forces2
{
same information as above, the only difference should be the patch name
}
)

[Bashar]

Thanks a lot for your help