[Joanna Huang]

Hi Foamers:
I am calculating the forces of a train.stl cases, it contains different patches like bogie, pantagraph, coach body, etc. I want to export the forces of different patches, so I write all the patches in the forces function file, but it does not work, the forces.dat file are alway the total forces, Can anyone help me with this, Thank you so much for that.

[Joanna Huang]

the OF version i used is v2.1.1

[tomf]

Hi Joanna,

You can get multiple versions of the forces by just making more forces entries in the controlDict. The example below gives you different folders, in this case:

Total, Body, pantagraph. Of course you have to put in the correct patch names for all the different parts.

    Total //name of output folder     
    {      type forces;
            functionObjectLibs ("libforces.so");
            patches //includes the contributions of these patches         
            (
               Patch1 Patch2 Patch3
            );         
            rhoName         rhoInf;
            pName             p;
            rhoInf          1.225;
            CofR            (0 0 0);         
            outputControl   timeStep;         
            outputInterval  1;
     }
    pantagraph //name of output folder     
    {      type forces;
            functionObjectLibs ("libforces.so");
            patches //includes the contributions of these patches         
            (
               pantagraph
            );         
            rhoName         rhoInf;
            pName             p;
            rhoInf          1.225;
            CofR            (0 0 0);         
            outputControl   timeStep;         
            outputInterval  1;
     }
    Body //name of output folder     
    {      type forces;
            functionObjectLibs ("libforces.so");
            patches //includes the contributions of these patches         
            (
               coachBody
            );         
            rhoName         rhoInf;
            pName             p;
            rhoInf          1.225;
            CofR            (0 0 0);         
            outputControl   timeStep;         
            outputInterval  1;
     }

Regards,
Tom

[Joanna Huang]

Hi Tom:

Thank you so much for that. I will try that.

[openfoam_user]

Hi Joanna,

can you upload some pictures (mesh, pressure contours, streamlines, ...) of your work about train aerodynamics ?

Best regards,
Stephane.