snappyHexMesh interfaceRefine does not work as expected

Summary

snappyHexMesh interfaceRefine should 'fill in' refinement such that islands of coarse cells surrounded by fine cells get refined. This avoid excessive changes in refinement level. In the picture below the cells-to-be-refined are in red

Steps to reproduce

Example case

E.g. https://exchange.openfoam.com/node/2248 (cylinder with some refinement)

What is the current bug behaviour?

It picks too many cells since it did not check for neighbouring refinement level, only for 'oppositeness'.

What is the expected correct behavior?

In picture above correctly identify the red cells and refine them

Relevant logs and/or images

Environment information

• OpenFOAM version : v2306

Possible fixes

in snappyRefineDriver::refinementInterfaceRefine make sure to test the neighbouring refinement level.