A numerical study of vortex breakdown in turbulent swirling flows

Solutions to the incompressible Reynolds-averaged Navier-Stokes equations h ave been obtained for turbulent vortex breakdown within a slightly divergin g tube. Inlet boundary conditions were derived from available experimental data for the mean flow and turbulence kinetic energy The performance of bot h two-equation and full differential Reynolds stress models was evaluated. Axisymmetric results revealed that the initiation of vortex breakdown was r easonably well predicted by thr differential Reynolds stress model. However , the standard K-epsilon model failed to predict the occurrence of breakdow n. The differential Reynolds stress,model also predicted satisfactorily the mean azimuthal and axial velocity profiles downstream of the breakdown, wh ereas results using the K-epsilon model were Insatisfactory. [S0098-2202(00 )01601-1].