[ata]

Hi FOAMers
can any one tell me U.correctBoundaryConditions() in icoFoam code is for what?
Thanks a lot

[boger]

It is an explicit command to update the boundary conditions on U because U has been modified explicitly on the line before. In contrast, when U and p are updated by solving systems of equations, the boundary conditions are updated implicitly as part of the Matrix "solve".

[salman189]

Thank you very much
May be my question is a low level one. Why there is not P.correctBoundaryConditions(); in the icoFoam solver?
Thanks a lot

[ata]

Thanks a lot

[boger]

As I said, it is because p is updated by solving a system of equations, and the boundary conditions are updated implicitly as part of the Matrix "solve". If you look in finiteVolume/fvMatrices/fvMatrix/fvMatrixSolve.C, for example, you will see that correctBoundaryConditions() is called as the final instruction in Foam::fvMatrix<Type>::solve.

[ata]

Thank you very much again

[sharonyue]

Originally Posted by boger

It is an explicit command to update the boundary conditions on U because U has been modified explicitly on the line before. In contrast, when U and p are updated by solving systems of equations, the boundary conditions are updated implicitly as part of the Matrix "solve".

Hi David,

As U have said, so the velocity field after "U.correctBoundaryConditions()" should changes. but why there is no difference in my result? I rewmake the icoFoam's code:

           ......................................
            #include "continuityErrs.H"

            U = HbyA - rAU*fvc::grad(p);
Info << U << endl;
            U.correctBoundaryConditions();
Info << U << endl;
           ......................................

I make a testify in the cavity case.
Thanks in advance.

[mnajafi]

I guess because U is a volVectorField and it's not defined on boundaries (but on cell centers), you can't observer changes using Info. To see the difference check Info<<fvc::interpolate(U)<<endl; before and after U.correctBoundaryConditions(). As you would see, interpolate returns correct value for boundaries just after correctBoundaryConditions().