[Junyu]

Hi, everyone. I'm about to write a dynamic boundary with codedFixedValue.
I want to use the pressure to force the boundary deform and move, so I need the pressure value on the boundary points.

Now I can successfully obtain the pressure on the volume center on the boundary by the following code:

PHP Code:

label cylinderID = patch.boundaryMesh().findPatchID("cylinder");
const volScalarField& tempP = this->db().objectRegistry::lookupObject<volScalarField>("p");
const fvPatchField<scalar>& cylinderP = tempP.boundaryField()[cylinderID]; 


The question is how to interpolate this to a pointField on the boundary?
Maybe there are also some other ways to get boundary points infomation that I don't know, so any suggestions or discussions would be helpful. Thanks in advance!

[Junyu]

OK, I found a way: use primitivePatchInterpolation. It returns the field on the boundary point. Here is the corresponding code and "primitivePatchInterpolation.H" should be included.

const volScalarField& tempP = this->db().objectRegistry::lookupObject<volScalarField>("p");
const scalarField& cylinderFaceP = tempP.boundaryField()[cylinderID];
primitivePatchInterpolation facePointInterpP(tempP.mesh().boundaryMesh()[cylinderID]);   
auto cylinderP = facePointInterpP.faceToPointInterpolate(cylinderFaceP)();

Then cylinderP elements can be accessed with the form "cylinderP[x]".
By the way, I found that openFoam8 has both "primitivePatchInterpolation" and "PrimitivePatchInterpolation" class. When the upper letter case is selected, the errors will be reported.
And also, it is valid to declare cylinderFaceP either as "scalarField&" type or "fvPatchField<scalar>" type, but the latter one cannot match the argument of the interpolation function.