Properties of the Scheme

1. It is a cell-centered discretization for arbitrary hexahedral meshes but has both cell-center and face-center intensities.

2. It gives second-order convergence of the intensity on both smooth and non-smooth meshes both with and without material discontinuities.

3. It generates a sparse SPD coefficient matrix.

4. It is equivalent to the standard 7-point cell-center diffusion discretization scheme when the mesh is orthogonal.