fvMatrix::setValues uses whichPatch to find patch

Functionality to add/problem to solve

E.g. wall functions apply fvMatrix constraints through fvMatrix::setValuesFromList. This uses polyBoundaryMesh::whichPatch to find the patch. For large numbers of patches this might get quite slow, especially since the wall-cells will have at least one face on a boundary.

Target audience

Turbulent flow with wall functions

Proposal

use polyBoundaryMesh::patchID(const label meshFacei) instead

(uses cached patch index per boundary face)