A 'similarity' solution for laminar swirling core flows

The far downstream region of laminar core flows with weak, strong, or very strong swirl embedded in a uniform parallel following stream is investigated analytically. Linearized similarity solutions based on the small-axial-disturbance-velocity assumption of Oseen are obtained using methods similar to those employed by Batchelor (1964) for strong trailing vortices. Strong swirl is shown to reduce axial velocity on and near the core axis, with two reversals as distance from the axis increases. Very strong swirl (a momentumless jet) is associated with an axial velocity profile having its maximum off the center line.