Divergence Properties of the Non-Standard Finite Difference for Rectangular Meshes

In this paper, the regular NSFD scheme minimized the dispersion error at a designed frequency. However, it does not satisfy the divergence-free nature for the rectangular meshes. On the contrary, the corrected NSFD scheme satisfies the divergence-free nature for the non-square mesh case. However, it sacrifices the dispersion performance. There is always a compromise depending on what kind of problem that needs to be solved