Demonstration of the APR boundaries used (16 levels in the figure). The spherical boundaries are centered on the MBH. The outermost boundary is at r = 2200R_g ≈ 3.25 × 10¹⁴ cm with Δr = 137.5R_g ≈ 2.03 × 10¹³ cm between each boundary, where R_g = R_s/2 = GM/c² is the gravitational radius of the MBH. r = 2200R_g is the same in all simulations, whereas Δr = 1100, 550, 275, and 183.3 for 2-, 4-, 8-, and 12-level simulations, respectively.