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RAPID AXISYMMETRIC CONTRACTION OF GRID-GENERATED TURBULENCE AND THE REYNOLDS-STRESS MODELS AT RAPID DISTORTION LIMIT

Ozgur Ertunc
LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-Universitat Erlangen-Nurnberg, Cauerstrasse 4, D-91058 Erlangen, Germany

Cagatay Koksoy
LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-Universitat Erlangen-Nurnberg, Cauerstrasse 4, D-91058 Erlangen, Germany

Subhashis Ray
Institute of Thermal Engineering, Technische Universitat Bergakademie Freiberg, Gustav-Zeuner-Strasse 7, D-09596 Freiberg, Germany

Franz Durst
FMP TECHNOLOGY GMBH, Am Weichselgarten 34, 91058 Erlangen, Germany

Abstrakt

Rapid distortion of mean-velocity in turbulent flows can be encountered in many technological applications, and hence, it is important to know the prediction performance of the available and widely used Reynolds-stress models under conditions where rapid distortion theory (RDT) is valid. Axisymmetric contraction of grid-generated turbulence is one class of homogeneous turbulent flows, which can approach to the RDT limit under highly strained condition and it is selected for the validation of various Reynolds-stress models in this study. For this purpose, available data on axisymmetric contraction are analyzed in terms of their accuracy and rapidity. The experimental data of Ertunc (2007) is found to be appropriate for this kind of validation at RDT limit. The Reynolds-stress models of Launder et al. (1975), Speziale et al. (1991), Sjogren and Johansson (2000), Jovanovic et al. (2003) are compared with the experimental data of Ertunc (2007) and the modified rapid distortion theory of Sreenivasan and Narasimha (1978). Since the rapid pressure strain term in the dynamic equation of Reynolds-stresses dominates the development of turbulence at the RDT limit, special emphasize is given to the differences in the models of this term and their consequences.