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Openfoam Post Processing Cumulative Drag

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Old   January 14, 2024, 08:05
Default Openfoam Post Processing Cumulative Drag
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Hello, I am doing a project about drag reduction devices for US Trucks. I am trying to add some cumulative drag plots too. But in my graphs it seems like the Cd is decreasing between the truck and the trailer. All the paper that i read says that it should increase due to the pressure difference. I also tested it with vortex traps set in front of the trailer. I am attaching my forceCoeffs file and my graphs. Can you give me feedback about what could went wrong or did i get wrong results.

Thank you all

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2306                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/

forceCoeffs1
{
    type            forceCoeffs;

    libs            (forces);

    writeControl    timeStep;
    timeInterval    1;

    log             yes;
    
    writeFields     yes;	// Store and write volume field representations of forces and moments
    
    patches (truckbase symmetry);

    rho             rhoInf;      // Indicates incompressible
    rhoInf          1;           // Required when rho = rhoInf
    liftDir         (0 0 1);
    dragDir         (1 0 0);
    CofR            (0 0 0); 	//The point around which your torque will be calculated. 
    pitchAxis       (0 1 0);
    magUInf         24.5872;		 // INPUT SPEED INITIAL
    lRef            20.315;        // Wheelbase length	the longest line in the x direction will be the lRef. 
    Aref            5.196;  //10.392;    
    
   /* binData
    {
        nBin        50;          // output data into 20 bins
        direction   (1 0 0);     // bin direction
        cumulative  yes;
    }*/   
}


binField1
{
    type                    binField;
    libs                    (fieldFunctionObjects);
    binModel                singleDirectionUniformBin;
    fields                  (forceCoeff);
    patches                 (truckbase);
    decomposePatchValues    true;
    CofR                    ${../forceCoeffs1/CofR};

    binData
    {
        nBin        50;          // 
        direction   (1 0 0);     // bin direction
        cumulative  yes;
    }
    writeControl            timeStep;
}
Attached Images
File Type: png base_vortex_graph.png (26.6 KB, 13 views)
File Type: png base_cum_drag (1)-overlay.png (46.6 KB, 15 views)
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drag coefficient, force coefficients, opeanfoam, post processing

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