[laurenj95]

Originally Posted by rudolf.hellmuth

Paraboloid velocity profile on a circular patch:

    inlet
    {
        type            codedFixedValue;
        value           uniform (0 0 0);
        redirectType    Poiseuille;   
        code
        #{
            const fvPatch& boundaryPatch = patch(); 
            const vectorField& Cf = boundaryPatch.Cf(); 
            vectorField& U = *this;
        
            //gfunc calculates the function on decomposed patches for parallel runs.
            scalar patchArea = gSum(boundaryPatch.magSf());
            //Info << "Patch area: " << patchArea << endl;
            
            vector ctr = gSum(boundaryPatch.magSf()*Cf)/patchArea;
            //Info << "Patch center: " << ctr << endl;
            
            scalar R = sqrt(patchArea/constant::mathematical::pi);
            //Info << "Patch radius: " << R << endl;
            
            vector n = gSum(boundaryPatch.magSf()*boundaryPatch.nf())/patchArea;
            //Info << "Patch mean normal: " << normal << endl;
            
            scalar Umean = 1.0;
            
            forAll(Cf, i)
            {
                U[i] = -n*2.0*Umean*(1.0 - sqr(mag(Cf[i] - ctr)/R));
            }
            // operator==(vector(1.0, 0.0, 0.0));
        #};
    }

This codedFixedValue BC is working for me. You can use this code to compile a PoiseuilleBC.so if you want.

I hope it can help you,
Rudolf

Hi,

How may I modify this for flow in the y-direction with the inlet centre at coordinates [0 -0.010 0]

Thanks,

Lauren

[syedfaisalpasha]

My bad

I am not able to implement parabolic velocity condition though I followed the instructions.Can anyone please help me in solving this issue.
Thanks and Regards
syedfaisalpasha

[pardoa]

Hello everyone,

This is an old post that helped me a lot to code the paraboloid profile that I wished to define my velocity BC at the inlet from an input flowrate.

I post here the piece of code for anyone who wishes/needs to use it:

// Get range and orientation
boundBox bb(patch().patch().localPoints(), true);

//Parabola centre
vector paraCtr = vector(0.5*(bb.max() + bb.min()).x(),0.5*(bb.max() + bb.min()).y(),bb.max().z()); // For an open channel with paraCtr at the top centre

//Patch faces centres
const vectorField& cellCtr = patch().Cf();

//Patch face normal vectors
vectorField n(patch().nf());

// Patch mean normal: weighted mean of patch face normal vectors
vector n_vector = gSum(patch().magSf()*n)/gSum(patch().magSf());

//Depth direction
vector depthDir = (0 0 1);

//Transversal direction
vector transDir = n_vector ^ depthDir;

// Patch height and width 
scalar pHeight = ((bb.max() - bb.min()) & depthDir);
scalar pWidth = ((bb.max() - bb.min()) & transDir);

// Calculate local 1-D coordinate for the parabolic profile
scalarField verCoord = ((cellCtr - paraCtr) & depthDir_)/pHeight;
scalarField horCoord = ((cellCtr - paraCtr) & transDir)/(0.5*pWidth);	// Multiply by 0.5 to get the distance from the centre of the parabola to the patch end

//Mean velocity
scalar avgU = -flowRate/gSum(patch().magSf());

// Mean velocity multiplier to get the max velocity (centreline velocity)
scalar avgUmulti=2;

operator==(n*avgUmulti*avgU*(1.0 - sqr(verCoord))*(1.0 - sqr(horCoord)));

Hope this can help someone.

Álvaro