Outflow selection slice perpendicular to the disk in run  NOTURB, showing three of the eight steps to compute its opening angle. Displayed are the projection vector p_i associated to cell i (Eq. (3), left panel), the four subselections based on this projection (middle panel) and the geometric center vector u, and two of the outermost positions vectors r_2,± used to compute the opening angle (Eq. (4), right panel). The circle shows the sink position that we consider as the coordinates origin.