Once you choose the RNG model, the swirl modification takes effect, by default,
for all three-dimensional flows and axisymmetric flows with swirl. The default
swirl constant (
12.4-8) is set to 0.07, which
works well for weakly to moderately swirling flows. However, for strongly
swirling flows, you may need to use a larger swirl constant.
To change the value of the swirl constant, you must first turn on the Swirl Dominated Flow option under RNG Options in the Viscous Model panel. (This option will not appear unless you have activated the RNG - model.)