Left: surface density snapshot from the GRAMVAC simulation of a disc orbiting a a = 0.995 black hole. At this later stage the initial uniform disc has turned into a disc exhibiting an inner edge whose location coincides with the last stable orbit around the black hole. Right: evolution of the density fit parameters as a function of the spin of the black hole, namely δ_r as the thickness of the edge and r_edge as its position as defined in Eq. (5).