Ruith, Michael R.; Meiburg, Eckart Direct numerical simulation of spatially developing, three-dimensional swirling jets. (English) Zbl 1083.76543 J. Turbul. 3, Paper No. 65, 8 p. (2002). Summary: Vortex breakdown of nominally axisymmetric, swirling incompressible jets and wakes issuing into a semi-infinite domain is studied by means of direct numerical simulations, as well as by local and global linear stability analyses. A two-parameter low entrainment velocity profile, for which the steady axisymmetric breakdown is well studied [W. J. Grabowski and S. A. Berger, J. Fluid Mech. 75, 525-544 (1976; Zbl 0336.76007)], is selected to discuss the role of the applied swirl in the existence and mode selection of vortex breakdown. As the swirl parameter is increased, bubble, helical and double-helical breakdown modes are observed for the moderate Reynolds number applied. It is shown that a local transition from supercritical to subcritical flow, as defined by T. B. Benjamin [J. Fluid Mech. 14, 593-629 (1962)], accurately predicts the swirl parameter yielding breakdown. Thus the basic form of breakdown is axisymmetric. A transition to helical breakdown modes is shown to be caused by a sufficiently large pocket of absolute instability in the wake of the bubble, giving rise to a self-excited global mode. Preliminary axisymmetric results of a global linear instability analysis agree favourably with the direct numerical simulation and thus encourage extension of the global analysis to helical modes. Cited in 2 Documents MSC: 76F65 Direct numerical and large eddy simulation of turbulence 76D25 Wakes and jets 76E99 Hydrodynamic stability Keywords:vortex breakdown; absolute instability; linear instability analysis Citations:Zbl 0336.76007 PDFBibTeX XMLCite \textit{M. R. Ruith} and \textit{E. Meiburg}, J. Turbul. 3, Paper No. 65, 8 p. (2002; Zbl 1083.76543) Full Text: DOI Link References: [1] DOI: 10.1017/S0022112076000360 · Zbl 0336.76007 · doi:10.1017/S0022112076000360 [2] DOI: 10.1017/S0022112062001482 · Zbl 0112.40705 · doi:10.1017/S0022112062001482 [3] Maxworthy T 2001 Private communication [4] Ruith M R, Comput. Fluids (2002) [5] DOI: 10.1016/0045-7930(88)90012-6 · Zbl 0662.76034 · doi:10.1016/0045-7930(88)90012-6 [6] DOI: 10.1017/S0022112072002046 · Zbl 0252.76033 · doi:10.1017/S0022112072002046 [7] DOI: 10.1098/rspa.1982.0105 · doi:10.1098/rspa.1982.0105 [8] Ruith M R, Phys. Fluids 14 pp S11– (2002) [9] DOI: 10.1017/S0022112097007787 · Zbl 0905.76030 · doi:10.1017/S0022112097007787 [10] Olendraru C, C. R. Acad. Sci. Paris II 323 pp 153– (1996) [11] DOI: 10.1063/1.870045 · Zbl 1147.76469 · doi:10.1063/1.870045 [12] Chen P, PhD Thesis (2000) This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.