RT Journal Article ID 1e55f2f83517c2a5 A1 Dinesh, K. K. J. Ranga A1 Savill, A. M. A1 Garry, K. P. A1 Holt, J. C. A1 Poll, D. I. A. A1 Kirkpatrick, Michael P. T1 Modelling of Coaxial Jet Efflux Mixing using LES JF International Journal of Fluid Mechanics Research JO FMR YR 2012 FD 2012-02-03 VO 39 IS 1 SP 20 OP 39 AB A detailed study has been performed to investigate passive scalar mixing of turbulent co-flowing jets in their initial exhaust development region, as a complement to separate experimental studies, to provide better defined initial conditions for subsequent simpler model predictions of the effect of aircraft engine plume/vortex interactions on air quality. Accordingly a well-established Large Eddy Simulation (LES) technique has first been validated against experimental data for a low-speed turbulent round jet and then used to perform a parametric series of simulations, numerical experiments, for a coaxial jet representative of a modern, large by-pass ratio jet engine exhaust under a variety of conditions with passive scalar introduced into either the core or bypass flow. Effects of free-stream velocity, swirl, and boundary proximity have all been considered and conclusions drawn. The comparisons between LES data and experiment measurements were in good agreement for low-velocity round jet. For a higher-velocity coaxial jet, initial instabilities on the shear boundary between the core and by-pass flows were seen to quickly develop into large scale coherent (vortex) motions which grew in scale and lost energy to a broader range of motions at downstream. The numerical databases generated for this series of coaxial jet configurations provide a valuable source of information for more accurately initialising lower order modelling of subsequent jet efflux development and vortex interaction. PB Begell House LK https://www.dl.begellhouse.com/journals/71cb29ca5b40f8f8,0654707d1b843844,1e55f2f83517c2a5.html