CFD Online Discussion Forums - Vector Center Face ---> Cells

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Vector Center Face ---> Cells

Hello to all,
i'm going to modify the equations at the boundary to run an adjoint simulation.
One of these equations includes a term r which is defined as the position vector starting from the center of the outlet surface.
I know the face center can be accessed by the function Cf() but i don't know how to set it for the entire outlet boundary and for the single cell.
Could someone help me defyning it?

Thanks for help,
Roberto

Sorry for Bump,
i have not resolved the problem yet

here my equation:

Code:

u_tw = 1/(v_n - nu/h)*(-nu/h*u_(tw-1) + 2*(n x r)/|| r x v_t ||^(3) )

and here what i implemented

Code:

void Foam::adjointOutletVelocityFvPatchVectorField::updateCoeffs()

{

    if (updated())

    {

        return;

    }



//    const fvsPatchField<scalar>& phiap =

//        patch().lookupPatchField<surfaceScalarField, scalar>("phia");



    const fvPatchField<vector>& Up =

        patch().lookupPatchField<volVectorField, vector>("U");



    const fvPatchField<vector>& Uap =

        patch().lookupPatchField<volVectorField, vector>("Ua");



    const scalarField& deltainv = patch().deltaCoeffs(); // Distance^(-1)



    vectorField Uaneigh   = Uap.patchInternalField();               // Vettore

    vectorField Uaneigh_n = (Uaneigh & patch().nf())*patch().nf();  // Normale

    vectorField Uaneigh_t = Uaneigh - Uaneigh_n;                    // Tangente 



    vectorField Up_n = (Up & patch().nf())*patch().nf();  // Normale

    vectorField Up_t = Up - Up_n;                         // Tangente



    scalarField U_t = mag(Up_t);

    scalarField U_n = mag(Up_n);



    vectorField n = patch().nf();



 

    scalar nu = readScalar(db().lookupObject<IOdictionary>("transportProperties").lookup  

    ("nu"));



    vectorField :: operator = (1 /(U_n - nu * deltainv) * (-nu * Uaneigh_t * deltainv + 2*(n^Uaneigh) / pow (mag(Uaneigh ^ Up_t),3)));



    fixedValueFvPatchVectorField::updateCoeffs();

}

I have only to define r

Hi again,

Can i use something like this? Is it right for my scope?

Code:

vectorField r = patch().Cf()-(10 15 30);

Where

Code:

patch().Cf()

is the face cell center (if i understood the command) coordinates and (10 15 30) the center coordinates of my boundary. Unfortunately it gives me an error i think it could derived from how i define the vector (10 15 30);

Regards,
Roberto

Hi,
To get the center of the patch try using a bounding box, then average the limits. it would be your center. For the code you have up there, change it to this:

Quote:

vectorField r = patch().Cf()-vector(10 15 30);

Hi Mahdi, thanks for your reply.
Your solution is almost perfect but it's necessary to insert a comma between the elements vectors.

Code:

vectorField r = patch().Cf()-vector(10,15,30);

Many thanks.

Best Regards,
Roberto