Publication: Buoyancy-corrected k-epsilon models and Large Eddy Simulation applied to a large axisymmetric helium plume

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Title	Buoyancy-corrected k-epsilon models and Large Eddy Simulation applied to a large axisymmetric helium plume
Authors/Editors*	W. Chung and C.B. Devaud
Where published*	International Journal for Numerical Methods in Fluids
How published*	Journal
Year*	2008
Volume	58
Number
Pages	57-89
Publisher
Keywords
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Abstract	The present numerical study is focused on testing two different modeling approaches to simulate a large turbulent buoyant helium plume, in particular the near-field region. First, buoyancy-corrected kâ models are applied in Reynolds-averaged NavierâStokes (RANS) calculations, then large eddy simulation (LES) using a standard Smagorinsky model is examined. Good results are produced using the buoyancy-corrected models, in particular, excellent agreement is achieved for the radial profiles of the streamwise velocity. However, the predictions are very sensitive to the choice of the buoyancy constant, C3, in the models. The present LES calculations show that the puffing frequency is accurately predicted. Predictions for the time-averaged velocities are within experimental uncertainty at all locations. The predicted plume concentrations are in good agreement at the base of the plume, but the centerline values are overpredicted farther downstream. The higher-order statistics are best predicted with the finest mesh. A sensitivity analysis on grid refinement, values of the Smagorinsky constant and the Schmidt number are included.