Width of the horseshoe flow and the x-coordinate of the critical recycling streamline at the edge of the computational domain of hydrodynamical simulations. The solid, dotted, and dashed gray lines are given by the analytic formulae for the width of the horseshoe region (Eqs. (14) and (15)). The numerically calculated width of the outflow region (x_rec,num, the circle symbols) is in better agreement with the analytic estimate based on Eq. (15) (, the solid lines) than Eq. (14) (the dashed line). The numerically calculated width of the horseshoe region (w_HS,num, the squares symbols) is in good agreement with Eq. (14) (, the dotted lines).