A numerical study of vortex breakdown in turbulent swirling flows

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