[THUCT]

Hello guys!
I am reading the code's of solver reactingFoam in Openfoam. There is some sentences in YEqn.H:

 
    1 tmp<fv::convectionScheme<scalar>> mvConvection
    2 (
    3     fv::convectionScheme<scalar>::New
    4     (
    5         mesh,
    6         fields,
    7         phi,
    8         mesh.divScheme("div(phi,Yi_h)")
    9     )
   10 );
   11 
   12 {
   13     reaction->correct();
   14     Qdot = reaction->Qdot();
   15     volScalarField Yt(0.0*Y[0]);
   16 
   17     forAll(Y, i)
   18     {
   19         if (i != inertIndex && composition.active(i))
   20         {
   21             volScalarField& Yi = Y[i];
   22 
   23             fvScalarMatrix YiEqn
   24             (
   25                 fvm::ddt(rho, Yi)
   26               + mvConvection->fvmDiv(phi, Yi)
   27               - fvm::laplacian(turbulence->muEff(), Yi)
   28              ==
   29                 reaction->R(Yi)
   30               + fvOptions(rho, Yi)
   31             );
   32 
   33             YiEqn.relax();
   34 
   35             fvOptions.constrain(YiEqn);
   36 
   37             YiEqn.solve(mesh.solver("Yi"));
   38 
   39
   40 
   41             Yi.max(0.0);
   42             Yt += Yi;
   43         }
   44     }
   45 
   46     Y[inertIndex] = scalar(1) - Yt;
   47     Y[inertIndex].max(0.0);
   48 }

I tracked the

 fvOptions.correct(Yi);

and

fvOptions.constrain(YiEqn);

It turned to be as following:

 void Foam::fv::option::correct(volScalarField& field)
{}

and

 void Foam::fv::option::constrain(fvMatrix<scalar>& eqn, const label fieldi){}

I think it does not make any change in the program.But I do not understand why the programmer put them there. Could anyone clear this confusion?
Best regards!