A Numerical Study of Vortex Breakdown in Turbulent Swirling Flows

Abstract

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 the differential Reynolds stress model. However, the standard K-ε 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-ε model were unsatisfactory. [S0098-2202(00)01601-1]

Simulations of confined turbulent vortex flow

“…Besides e.g. the work by Spall and co-workers [31,32], this is one of the first reports of three-dimensional simulation of turbulent vortex breakdown in conjunction with experimental validation.…”

Separation performance predictions of a Stairmand high‐efficiency cyclone

“…or more generally strongly swirling flow have learned that Reynolds stress models need to be applied to capture the Ž most important aspects of the average flow field Hoekstra et . al., 1999;Spall and Ashby, 2000 . Accurate predictions with respect to the flow's fluctuations are very difficult to get and most likely require very fine grids.…”

Prediction of strongly swirling flow within an axial hydrocyclone using two commercial CFD codes

“…Two equation Eddy Viscosity Models (EVM), such as the popular k-ε model (KEM), which can successfully predict many engineering flows, are unable to account for the extra strains caused by the streamline curvature, recirculation, and swirl (Hanjalić, 1999;Leschziner, 1990Leschziner, , 2000. This has been confirmed by the poor performance achieved when the KEM was used to model the swirling flow within geometries such as combustion chambers and pipes (Chang and Chen, 1993;Chen, 1986;Chen and Chang, 1995;Chen and Lin, 1999;Hogg and Leschziner, 1989;Jones and Pascau, 1989;Kobayashi and Yoda, 1987;Lu and Semião, 2003;Sharif and Wong, 1995;Sloan et al, 1986;Spall and Ashby, 2000;Tsai et al, 1995;Wennerberg and Obi, 1993;Xia et al, 1997;Yeh and Lin, 2000). Typical problems encountered when applying the KEM to (strongly) swirling flow include the inability to predict the correct tangential velocity profile due to strong radial diffusion of momentum and the overprediction of the shear stresses.…”

“…Examples in the literature of the DRSM applied to the prediction of the turbulent swirling flow without core recirculation include: Chen and Lin (1999), Hogg and Leschziner (1989), Jones and Pascau (1989), Sharif and Wong (1995), Spall and Ashby (2000), Tsai et al (1995), Yeh and Lin (2000), Yuan and So (1998). These flows are easier to model numerically because the equations of motion are parabolic and as a result some simplifications can be made.…”