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Buoyancy‐corrected k –ε models and large eddy simulation applied to a large axisymmetric helium plume
Author(s) -
Chung W.,
Devaud C. B.
Publication year - 2008
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.1720
Subject(s) - reynolds averaged navier–stokes equations , buoyancy , plume , large eddy simulation , mechanics , turbulence , rotational symmetry , computational fluid dynamics , reynolds number , meteorology , physics
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 k –ε models are applied in Reynolds‐averaged Navier–Stokes (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, C 3ε , 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. Copyright © 2008 John Wiley & Sons, Ltd.