[Saideep]

Hello Foamers;

I have a question regarding a library (interfaceProperties.C) used by the interFOAM solver.

There is a private member function names "correctContactAngle".

Can anyone throw some light on how the interface normal on the boundary is being corrected. I can follow up-to certain portion of the function which I commented and few transformations at the end of the function look confusing.

void Foam::interfaceProperties::correctContactAngle
(                           
  surfaceVectorField::GeometricBoundaryField& nHatb /*we pass the interface normal vector in patches*/
) const                       
   {                           
      const fvMesh& mesh = alpha1_.mesh();                           
      const volScalarField::GeometricBoundaryField& gbf = alpha1_.boundaryField();                        
      const fvBoundaryMesh& boundary = mesh.boundary();                        
                       
      forAll(boundary, patchi)
         {
                if (isA<alphaContactAngleFvPatchScalarField>(gbf[patchi]))                               
                   {                                   
                     const alphaContactAngleFvPatchScalarField& gcap =  refCast<const alphaContactAngleFvPatchScalarField> (gbf[patchi]);                       
                     fvsPatchVectorField& nHatp = nHatb[patchi];                                   
                     scalarField theta = convertToRad*gcap.theta(U_.boundaryField()[patchi], nHatp);                        
                     vectorField nf = boundary[patchi].nf(); /*is the face normal vector on a patch*/
                       
                     // Reset nHatp to correspond to the contact angle                        
                      scalarField a12 = nHatp & nf; /*should be a surface scalar field*/
                       
                      scalarField b1 = cos(theta);                        
                      scalarField b2(nHatp.size());                        

                      /* how does the following part correct the interface normal vector on the patches?*/
                      forAll(b2, facei)    
                        {                                       
                           b2[facei] = cos(acos(a12[facei]) - theta[facei]);   
                         }                        
                      scalarField det = 1.0 - a12*a12;                        
                      scalarField a = (b1 - a12*b2)/det;                                   
                      scalarField b = (b2 - a12*b1)/det;                        
                      nHatp = a*nf + b*nHatp;                        
                        nHatp /= (mag(nHatp) + deltaN_.value());
                  }
                }
             }

[Cyp]

Hi Saideep!

Look at page 49 and 50 of the PDF https://pangea.stanford.edu/ERE/pdf/...veleau2016.pdf

Cheers,

[Saideep]

Hi Cyprien and Foamers;

In the void correctContactAngle function of interfaceProperties, what does the acap.gradient() do?

             acap.gradient() = (nf & nHatp)*mag(gradAlphaf[patchi]);     
                      acap.evaluate();

This function call is omitted in the foam-extend part of the correctContantAngle whereas present in the OpenFoam versions?

I am not sure how, but it looks like it re-orient the interface normal on the contact angle boundaries further after correcting the interface normal vector.

SaiD

[ashish.vinayak]

Hi Saideep,

Were you able to figure this out?

Best regards

Originally Posted by Saideep

Hi Cyprien and Foamers;

In the void correctContactAngle function of interfaceProperties, what does the acap.gradient() do?

             acap.gradient() = (nf & nHatp)*mag(gradAlphaf[patchi]);     
                      acap.evaluate();

This function call is omitted in the foam-extend part of the correctContantAngle whereas present in the OpenFoam versions?

I am not sure how, but it looks like it re-orient the interface normal on the contact angle boundaries further after correcting the interface normal vector.

SaiD