[ousoweak]

hi all

I am new to OpenFOAM programming and I want to get the distance between a specific point on the wall and the boundary-line of the wall. Related operations should be conducted in nutUspalding Wall Function file.

To achieve this, it is obviously that (1) I should get the point coordinate (x,y,z) and in .C file (2) get the 3D coordinate of the boundary-line. But I don’t know how to access them in openfoam?

Can anyone help me ? thanks.

Attached file is the sketch of the problem.

Yiming


The nutUspalding Wall Function file are list as fellow:

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// * * * * * * * * * * * * Protected Member Functions * * * * * * * * * * * //

tmp<scalarField> nutUSpaldingWallFunctionFvPatchScalarField::calcNu t() const
{
const label patchi = patch().index();

const turbulenceModel& turbModel = db().lookupObject<turbulenceModel>
(
IOobject::groupName
(
turbulenceModel:ropertiesName,
internalField().group()
)
);
const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];
const scalarField magGradU(mag(Uw.snGrad()));
const tmp<scalarField> tnuw = turbModel.nu(patchi);
const scalarField& nuw = tnuw();

return max
(
scalar(0),
sqr(calcUTau(magGradU))/(magGradU + ROOTVSMALL) - nuw
);
}


tmp<scalarField> nutUSpaldingWallFunctionFvPatchScalarField::calcUT au
(
const scalarField& magGradU
) const
{
const label patchi = patch().index();

const turbulenceModel& turbModel = db().lookupObject<turbulenceModel>
(
IOobject::groupName
(
turbulenceModel:ropertiesName,
internalField().group()
)
);
const scalarField& y = turbModel.y()[patchi];

const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];
const scalarField magUp(mag(Uw.patchInternalField() - Uw));

const tmp<scalarField> tnuw = turbModel.nu(patchi);
const scalarField& nuw = tnuw();

const scalarField& nutw = *this;

tmp<scalarField> tuTau(new scalarField(patch().size(), 0.0));
scalarField& uTau = tuTau.ref();

forAll(uTau, facei)
{
scalar ut = sqrt((nutw[facei] + nuw[facei])*magGradU[facei]);

if (ut > ROOTVSMALL)
{
int iter = 0;
scalar err = GREAT;

do
{
scalar kUu = min(kappa_*magUp[facei]/ut, 50);
scalar fkUu = exp(kUu) - 1 - kUu*(1 + 0.5*kUu);

scalar f =
- ut*y[facei]/nuw[facei]
+ magUp[facei]/ut
+ 1/(E_*exp(kappa_*0))*(fkUu - 1.0/6.0*kUu*sqr(kUu));

scalar df =
y[facei]/nuw[facei]
+ magUp[facei]/sqr(ut)
+ 1/(E_*exp(kappa_*0))*kUu*fkUu/ut;

scalar uTauNew = ut + f/df;
err = mag((ut - uTauNew)/ut);
ut = uTauNew;

} while (ut > ROOTVSMALL && err > 0.01 && ++iter < 10);

uTau[facei] = max(0.0, ut);
}
}

return tuTau;
}

[Jibran]

Originally Posted by ousoweak

hi all

I am new to OpenFOAM programming and I want to get the distance between a specific point on the wall and the boundary-line of the wall. Related operations should be conducted in nutUspalding Wall Function file.

To achieve this, it is obviously that (1) I should get the point coordinate (x,y,z) and in .C file (2) get the 3D coordinate of the boundary-line. But I don’t know how to access them in openfoam?

Can anyone help me ? thanks.

Attached file is the sketch of the problem.

Yiming


The nutUspalding Wall Function file are list as fellow:

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// * * * * * * * * * * * * Protected Member Functions * * * * * * * * * * * //

tmp<scalarField> nutUSpaldingWallFunctionFvPatchScalarField::calcNu t() const
{
const label patchi = patch().index();

const turbulenceModel& turbModel = db().lookupObject<turbulenceModel>
(
IOobject::groupName
(
turbulenceModel:ropertiesName,
internalField().group()
)
);
const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];
const scalarField magGradU(mag(Uw.snGrad()));
const tmp<scalarField> tnuw = turbModel.nu(patchi);
const scalarField& nuw = tnuw();

return max
(
scalar(0),
sqr(calcUTau(magGradU))/(magGradU + ROOTVSMALL) - nuw
);
}


tmp<scalarField> nutUSpaldingWallFunctionFvPatchScalarField::calcUT au
(
const scalarField& magGradU
) const
{
const label patchi = patch().index();

const turbulenceModel& turbModel = db().lookupObject<turbulenceModel>
(
IOobject::groupName
(
turbulenceModel:ropertiesName,
internalField().group()
)
);
const scalarField& y = turbModel.y()[patchi];

const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];
const scalarField magUp(mag(Uw.patchInternalField() - Uw));

const tmp<scalarField> tnuw = turbModel.nu(patchi);
const scalarField& nuw = tnuw();

const scalarField& nutw = *this;

tmp<scalarField> tuTau(new scalarField(patch().size(), 0.0));
scalarField& uTau = tuTau.ref();

forAll(uTau, facei)
{
scalar ut = sqrt((nutw[facei] + nuw[facei])*magGradU[facei]);

if (ut > ROOTVSMALL)
{
int iter = 0;
scalar err = GREAT;

do
{
scalar kUu = min(kappa_*magUp[facei]/ut, 50);
scalar fkUu = exp(kUu) - 1 - kUu*(1 + 0.5*kUu);

scalar f =
- ut*y[facei]/nuw[facei]
+ magUp[facei]/ut
+ 1/(E_*exp(kappa_*0))*(fkUu - 1.0/6.0*kUu*sqr(kUu));

scalar df =
y[facei]/nuw[facei]
+ magUp[facei]/sqr(ut)
+ 1/(E_*exp(kappa_*0))*kUu*fkUu/ut;

scalar uTauNew = ut + f/df;
err = mag((ut - uTauNew)/ut);
ut = uTauNew;

} while (ut > ROOTVSMALL && err > 0.01 && ++iter < 10);

uTau[facei] = max(0.0, ut);
}
}

return tuTau;
}

Hi,

The nodal coordinates can be obtained as

mesh.points()[nodeID]

and boundary face coordinates as

Cf.boundaryField()[patchID][facei]

Here the 'patchID' is the ID associated to a particular boundary and 'facei' is the local face numbering within that boundary.

[ousoweak]

Originally Posted by Jibran

Hi,

The nodal coordinates can be obtained as

mesh.points()[nodeID]

and boundary face coordinates as

Cf.boundaryField()[patchID][facei]

Here the 'patchID' is the ID associated to a particular boundary and 'facei' is the local face numbering within that boundary.

Thanks so much for your reply.
With your help,I can get the nodal coordinates by using the code "turbModel.mesh().points()[nodeID]" successfully.

But I still don't know how to get the "nodeID" of the current calculation grid point in the USpalding wall function.Can you help me?

Thank you again.

Yiming

[Jibran]

Originally Posted by ousoweak

Thanks so much for your reply.
With your help,I can get the nodal coordinates by using the code "turbModel.mesh().points()[nodeID]" successfully.

But I still don't know how to get the "nodeID" of the current calculation grid point in the USpalding wall function.Can you help me?

Thank you again.

Yiming

You are welcome. A solution could be to have nested loops on boundary patches, patch faces and then the nodes attached to the faces. I haven't tested this but something like this should work!

forAll(mesh.boundary(), patchID) 
{
    const word& patchName = mesh.boundary()[patchID].name(); 
 
    forAll (mesh.boundary()[patchID],facei) 
    {
         const label& faceID = mesh.boundaryMesh()[patchID].start() + facei;
         forAll (mesh.faces()[faceID], nodei)
         {
               const label& nodeID = mesh.faces()[faceID][nodei];
         }
    }
}

[ousoweak]

Originally Posted by Jibran

You are welcome. A solution could be to have nested loops on boundary patches, patch faces and then the nodes attached to the faces. I haven't tested this but something like this should work!

forAll(mesh.boundary(), patchID) 
{
    const word& patchName = mesh.boundary()[patchID].name(); 
 
    forAll (mesh.boundary()[patchID],facei) 
    {
         const label& faceID = mesh.boundaryMesh()[patchID].start() + facei;
         forAll (mesh.faces()[faceID], nodei)
         {
               const label& nodeID = mesh.faces()[faceID][nodei];
         }
    }
}

Thank you so much!!!
The code what you have written was exactly the right solution!

the code I used to get point coordinate in the wall function is:

vector pointX(0,0,0);
const label& faceID = patch().boundaryMesh()[patchi].start() + facei;
 forAll (turbModel.mesh().faces()[faceID], nodei)
         {
               const label& nodeID = turbModel.mesh().faces()[faceID][nodei];
        }
pointX=turbModel.mesh().points()[nodeID];

Thank you again~

Yiming

[Jibran]

Originally Posted by ousoweak

Thank you so much!!!
The code what you have written was exactly the right solution!

the code I used to get point coordinate in the wall function is:

vector pointX(0,0,0);
const label& faceID = patch().boundaryMesh()[patchi].start() + facei;
 forAll (turbModel.mesh().faces()[faceID], nodei)
         {
               const label& nodeID = turbModel.mesh().faces()[faceID][nodei];
        }
pointX=turbModel.mesh().points()[nodeID];

Thank you again~

Yiming

You are most welcome. I am glad that I could be of help. Enjoy!