[rajesh001]

Hi, Foamers, I am making some modifications on the icoFoam solver and needs some help in copying the boundary values of pressure field p and velocity field U to a new pressure field p1 and velocity field U1. I tried the following following code.

forAll(U.boundaryField(),patchI)        
{
          U1.boundaryField()[patchI] == U.boundaryField()[patchI] ;
 }
forAll(p.boundaryField(),patchI)
{
          p1.boundaryField()[patchI] == p.boundaryField()[patchI] ;
}

Surprisingly, the first part of the code (for Velocity) works without any problem. But for pressure, OpenFoam throws up an error

error: no match for ‘operator==’ (operand types are ‘const Foam::fvPatchField<double>’ and ‘const Foam::fvPatchField<double>’)   105 |           p1.boundaryField()[patchI] == p.boundaryField()[patchI] ; In file included from /home/proj/OpenFOAM/OpenFOAM-9/src/finiteVolume/lnInclude/volFields.H:40,                  from /home/proj/OpenFOAM/OpenFOAM-9/src/finiteVolume/lnInclude/surfaceInterpolationScheme.C:27,

I am a newbie in C++ and I am unable to understand the issue in this case. Is there any other method for this. I am using OpenFoam-9



Kindly help!
Thanks in advance.

[dlahaye]

How do you read the difference between = (one symbol) and == (two symbols)?

[olesen]

Originally Posted by dlahaye

How do you read the difference between = (one symbol) and == (two symbols)?

You can read the double equals as "forced assignment" (ie, copy in the values even if the BC is nominally not assignable).
Of course, this also implies that the left-hand-side is actually assignable. For example,

U1.boundaryFieldRef() == U.boundaryField();

Info: https://www.openfoam.com/documentati...ea65c28097d3f6