Meaning of int bcfcomp in FillPatchSingleLevel() and int cbccomp, int fbccomp, and int bcscomp in FillPatchTwoLevels()

[ZiyangHuang]

Hi!

I am trying to call FillPatchSingleLevel() and FillPatchTwoLevels() to fill a Multifab mf using data Vector<MultiFab> dof_new and Vector<Multifab> dof_old. Both dof_new and dof_old have Ncomp components. I also defined Vector<BCRec> bcs(Ncomp) storing the boundary conditions for individual components.

Right now, I am passing int scomp to int bcfcomp in FillPatchSingleLevel() and int cbccomp, int fbccomp, and int bcscomp in FillPatchTwoLevels(), but I am not sure if it is correct.

Thanks!

[cgilet]

It depends on what you're using for cbc and fbc. cbccomp will be the first component used within cbc, and fbccomp will be the first component used within fbc. You need to make sure all these components point to the same "thing", eg. x-velocity.

[WeiqunZhang]

Adding to what @cgilet said, bcfcomp will be passed to the physbcf argument. If your physbcf is amrex::PhysBCFunct and you have used Vector<BCRec> bcs(Ncomp) to create it, then amrex will assume that bcs[bcfcomp+icomp] is the boundary type for component dcomp+icomp of the destination multifab (i.e., mf) and component scomp+icomp of the source multifab (i.e., smf), where icomp is in [0,ncomp).

[ZiyangHuang]

Thanks for your replies. It is clear for me now.