Figure 2
From: Understanding turbulent free-surface vortex flows using a Taylor-Couette flow analogy
The planar laser induced fluorescence (PLIF) technique was used to provide a visualisation of the secondary flow field patterns. Rhodamine B dye was injected at (a) the vessel base and (b) the free-surface close to the inlet channel and (c) at the chamber perimeter which r o (θ). The presented images had a vortex Reynolds number of approximately ReΓ = 1.7 × 105 and M = 6.4 × 105. The dye was observed to be confined to bands along the tank base and at the free-surface in an inward positive direction which were in line with the observations of Anwar10 and Daggett and Keulegan9. A new flow process was also observed where the dye travelled upwards along the tank perimeter to convey a secondary flow to the free-surface and downwards at the near the vortex core at radius r a . This supplementary process outlined that some separation zone, possibly transient in nature, must occur at the tank base or walls. The flow processes outlined that the flow in global secondary field was quasi-toroidal. Figure 2c also highlights that the flow field exhibited some evidence of rotation.
