Experimental investigations of laminar swirling jets had revealed a new form of vortex
breakdown, named conical vortex breakdown, in addition to the commonly observed bubble
form. The present study explores these breakdown states that develop for the Maxworthy
profile (a model of swirling jets) at inflow, from streamwise-invariant initial conditions, with
direct numerical simulations. For a constant Reynolds number based on jet radius and a
centreline velocity of 200, various flow states were observed as the inflow profile's swirl …

The present study focusses on vortex breakdown (VB), which occurs in axially convected
swirling flows and is characterized by the development of an internal stagnation point and
regions of reverse flow. VB has been observed or utilized in a variety of situations including
flow over delta wings, tornadoes, re whirls, turbomachinery, fuel injectors and combustors.
Flows where VB is observed include swirling round jets with non-swirling and negligible co
flow. The experimental study of Billant et al.,(1998) has shown VB characteristics unique to …