Fig. 5
a Dimensionless vorticity magnitude of the unperturbed flow, ωtad on the horizontal mid-plane, \(\hat{z}=0\). b Dimensionless time-averaged angular velocity, \({\bar{{{\Omega }}}}_{x}{t}_{{{{\rm{ad}}}}}\), of the particle revolving about the outlet axis for different initial positions. c Outlet view of particle trajectories for \({\hat{x}}_{0}=0.0033\). Zones A and B indicate regions with small flow velocity magnitude (cf. Fig. 1d)
