A study of swirling flows in long straight pipes

The paper presents results of a study of the decay process of sw.irl in turbulent pipe flows. The experimental results, obtained using Laser-Doppler techniques, draw attention to a few flow effects not yet described thoroughly in the literature. A numerical analysis fails to predict some of these observed effects. Nevertheless, when a standard k-e : model is used, the rate of decay of the swirl is predicted to a fair degree of accuracy. The performance of second-order turbulence closures is less satisfying