Optimal 25-Point Finite-Difference Subgridding Techniques for the 2D Helmholtz Equation

Figure 1

(a) Subgridding method for a two-layered model, (b) the first kind node, (c) the second kind node, (d) the third kind node, and (e) the fifth kind node.

(a)

(b)

(c)

(d)

(e)