This example works both for a Schwarzschild and Kerr black holes.
Ready to plot:
The the Keplerian Orbits around a Schwarzschild (M=1) Black Hole (equatorial plane).
The effective potential for an accretion disk with l=3.75 (hand-picked to have an accretion disk with a cusp)
The accretion disk in 2D.
Changing l requires also to change the limits of second and third plot (vmax and vmin)