Study of Second-Moment Closure Models in Computations of Turbulent Shear Flows

1993 ◽  
pp. 53-62 ◽  
Author(s):  
A.O. Demuren ◽  
S. Sarkar
Keyword(s):  
Shear Flows ◽  
Moment Closure ◽  
Turbulent Shear ◽  
Second Moment ◽  
Closure Models ◽  
Turbulent Shear Flows ◽  
Second Moment Closure

A Comparison of Algebraic and Differential Second-Moment Closures for Axisymmetric Turbulent Shear Flows With and Without Swirl

1988 ◽  
Vol 110 (2) ◽  
pp. 216-221 ◽  
Author(s):  
S. Fu ◽  
P. G. Huang ◽  
B. E. Launder ◽  
M. A. Leschziner
Keyword(s):  
Shear Flows ◽  
Turbulent Jets ◽  
Moment Closure ◽  
Turbulent Shear ◽  
Turbulence Energy ◽  
Second Moment ◽  
Second Moment Closure ◽  
Transport Effects ◽  
Related Stress ◽  
Comparison Of The Results

Computations are reported for three axisymmetric turbulent jets, two of which are swirling and one containing swirl-induced recirculation, obtained with two models of turbulence: a differential second-moment (DSM) closure and an algebraic derivative thereof (ASM). The models are identical in respect of all turbulent processes except that, in the ASM scheme, stress transport is represented algebraically in terms of the transport of turbulence energy. The comparison of the results thus provides a direct test of how well the model of stress transport adopted in ASM schemes simulates that of the full second-moment closure. The comparison indicates that the ASM hypothesis seriously misrepresents the diffusive transport of the shear stress in nonswirling axisymmetric flows, while in the presence of swirl the defects extend to all stress components and are aggravated by a failure to account for influential (additive) swirl-related stress-transport terms in the algebraic modelling process. The principal conclusion thus drawn is that in free shear flows where transport effects are significant, it is advisable to adopt a full second-moment closure if turbulence modelling needs to proceed beyond the eddy-viscosity level.

A Comparison of Second-Moment Closure Models in the Prediction of Vortex Shedding From a Square Cylinder Near a Wall

2002 ◽  
Vol 124 (3) ◽  
pp. 728-736 ◽  
Author(s):  
Anthony G. Straatman ◽  
Robert J. Martinuzzi
Keyword(s):  
Computational Study ◽  
Moment Closure ◽  
Production Model ◽  
Square Cylinder ◽  
Trend Prediction ◽  
Second Moment ◽  
Closure Models ◽  
Second Moment Closure ◽  
The Difference ◽  
Gap Width

A computational study is presented that examines the capability of various second-moment closure models in the prediction of two-dimensional, nonstationary flow around a square cylinder in proximity to a wall. The linear return-to-isotropy/isotropization-of-production model RTI+IP and the nonlinear SSG pressure-strain models were combined with the DH and modified LUM diffusion models in the computations. In terms of global activity, the drag is well-predicted in terms of both magnitude and variation with cylinder-to-wall gap width S/D. The Strouhal number St was reasonably well-predicted in terms of magnitude, but the predicted trend with decreasing S/D was incorrect for all model combinations. The lift was not well-predicted in terms of magnitude or trend. Prediction of the detailed flow structure in the vicinity of the cylinder and in the wake was favourable, though the magnitudes of some velocity and Reynolds-stress components were over-predicted. It was argued that the large differences between the results at the intermediate gap width may be due to the difference between the measured and predicted critical gap widths. On the basis of the predicted global and detailed activity, the modified LUM model combined with the nonlinear SSG model was suggested as being the most viable combination for future studies.

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