Profiles of the disc half-thickness to radius ratio (H/r) at the last moment for all cases. The curve from 10r_s to 50r_s derives from our simulation, while the curve from 3r_s to 10r_s comes from the linear extrapolation. The starting points of extrapolated lines on the H/r curves are marked with solid coloured circles. The dashed black line represents H/r = 0.015, which is the criterion for determining the truncation radius.