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Computation of an unsteady complex geometry flow using novel non‐linear turbulence models
Author(s) -
Tucker Paul G.,
Liu Yan,
Chung Yongmann M.,
Jouvray Alex
Publication year - 2003
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.518
Subject(s) - turbulence , reynolds stress , reynolds stress equation model , context (archaeology) , mathematics , reynolds number , convergence (economics) , k epsilon turbulence model , turbulence kinetic energy , smoothing , geometry , k omega turbulence model , mechanics , physics , geology , statistics , economics , paleontology , economic growth
Non‐linear zonal turbulence models are applied to an unsteady complex geometry flow. These are generally found to marginally improve predicted turbulence intensities. However, relative to linear models, convergence is mostly difficult to achieve. Clipping of some non‐linear Reynolds stress components is required along with velocity field smoothing or alternative measures. Smoothing is naturally achieved through multilevel convergence restriction operators. As a result of convergence difficulties, generally, non‐linear model computational costs detract from accuracy gains. For standard Reynolds stress model results, again computational costs are prohibitive. Also, mean velocity profile data accuracies are found worse than for a simple mixing length model. Of the non‐linear models considered, the explicit algebraic stress showed greatest promise with respect to accuracy and stability. However, even this shows around a 30% error in total (the sum of turbulence and unsteadiness) intensity. In strong contradiction to measurements the non‐linear and Reynolds models predict quasi‐steady flows. This is probably a key reason for the total intensity under‐predictions. Use of LES in a non‐linear model context might help remedy this modelling aspect. Copyright © 2003 John Wiley & Sons, Ltd.