Direct numerical simulations of vortex breakdown in swirling jets

Vortex breakdown in swirling free jets exhibits a rich variety of flow structures in a compact subdomain of the flow field. Model equations assuming steady and rotationally symmetric motion above a conical stream surface show bi- and multi-stability (Shtern and Hussain 1996 J. Fluid Mech. 309 1-44) of several flow forms, hysteresis and negative thrust phenomena. Direct numerical simulations are used to investigate the development of the conical jet layer and its break up into three-dimensional vortex structures for moderate Reynolds numbers. Three-dimensional flows for swirl numbers at and above the threshold value observed experimentally (Billant et al 1999 J. Fluid Mech. 376 183-219) are considered. This article was chosen from selected Proceedings of the Eighth European Turbulence Conference (Advances in Turbulence VIII (Barcelona, 27-30 June 2000) (Barcelona: CIMNE) ed C Dopazo. ISBN: 84-89925-65-8).

[1]  New features of swirling jets , 2000 .

[2]  Steven A. Orszag,et al.  Dynamical aspects of vortex reconnection of perturbed anti-parallel vortex tubes , 1993 .

[3]  F. Hussain,et al.  Hysteresis in swirling jets , 1996, Journal of Fluid Mechanics.

[4]  W. Heinrichs,et al.  Spectral collocation methods and polar coordinate singularities , 1991 .

[5]  Symmetry breaking of the flow in a cylinder driven by a rotating end wall , 2000 .

[6]  Ashurst,et al.  Numerical study of vortex reconnection. , 1987, Physical review letters.

[7]  J. Lopez.  Characteristics of endwall and sidewall boundary layers in a rotating cylinder with a differentially rotating endwall , 1998, Journal of Fluid Mechanics.

[8]  H. K. Moffatt,et al.  The degree of knottedness of tangled vortex lines , 1969, Journal of Fluid Mechanics.

[9]  M. Carpenter,et al.  Several new numerical methods for compressible shear-layer simulations , 1994 .

[10]  Yuguo Li.  Wavenumber-Extended High-Order Upwind-Biased Finite-Difference Schemes for Convective Scalar Transport , 1997 .

[11]  F. Hussain,et al.  Instabilities of conical flows causing steady bifurcations , 1998, Journal of Fluid Mechanics.

[12]  Fazle Hussain,et al.  COLLAPSE, SYMMETRY BREAKING, AND HYSTERESIS IN SWIRLING FLOWS , 1999 .

[13]  Juan Lopez,et al.  On the bifurcation structure of axisymmetric vortex breakdown in a constricted pipe , 1994 .

[14]  A. Barrero,et al.  Solution breakdown in a family of self-similar nearly inviscid axisymmetric vortices , 1995, Journal of Fluid Mechanics.

[15]  M. S. Chong,et al.  A general classification of three-dimensional flow fields , 1990 .

[16]  Juan Lopez,et al.  Axisymmetric vortex breakdown Part 1. Confined swirling flow , 1990, Journal of Fluid Mechanics.

[17]  J. Chomaz,et al.  Experimental study of vortex breakdown in swirling jets , 1998, Journal of Fluid Mechanics.

[18]  Paul Bellan,et al.  Physical constraints on the coefficients of Fourier expansions in cylindrical coordinates , 1990 .

[19]  Juan Lopez,et al.  Axisymmetric vortex breakdown Part 2. Physical mechanisms , 1990, Journal of Fluid Mechanics.

[20]  J. Lopez,et al.  Axisymmetric vortex breakdown. Part 3 Onset of periodic flow and chaotic advection , 1992, Journal of Fluid Mechanics.