I would like to thank the reviewer for very important comment.
As requested by reviewer mentioned sentence was changed to "One of the possible approaches applied in the FD-BPM is to use the square grid ...". Moreover, it was added that the Crank-Nicolson scheme was applied for numerical simulations. Unforrtunatelly, because of space limitations additional information about numerical method, Laplacian discretization in different meshes, etc, could not be included.