Application of Second Moment Closure Models to Complex Flows: Part I—Wall Bounded Flows

1992 ◽  
pp. 575-588
Author(s):  
A. O. Demuren ◽  
S. Sarkar
Keyword(s):  
Moment Closure ◽  
Complex Flows ◽  
Second Moment ◽  
Closure Models ◽  
Second Moment Closure ◽  
Wall Bounded Flows

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.

A note on Tennekes hypothesis and its impact on second moment closure models

2005 ◽  
Vol 9 (1) ◽  
pp. 23-29 ◽  
Author(s):  
L. Kantha ◽  
J.-W. Bao ◽  
S. Carniel
Keyword(s):  
Moment Closure ◽  
Second Moment ◽  
Closure Models ◽  
Second Moment Closure

Realizability of second-moment closure via stochastic analysis

1994 ◽  
Vol 280 ◽  
pp. 395-407 ◽  
Author(s):  
P. A. Durbin ◽  
C. G. Speziale
Keyword(s):  
Langevin Equation ◽  
Stochastic Analysis ◽  
Present Method ◽  
Necessary Conditions ◽  
Moment Closure ◽  
Second Moment ◽  
Homogeneous Shear ◽  
Closure Models ◽  
Second Moment Closure ◽  
Homogeneous Shear Flow

It is shown that realizability of second-moment turbulence closure models can be established by finding a Langevin equation for which they are exact. All closure models currently in use can be derived formally from the type of Langevin equation described herein. Under certain circumstances a coefficient in that formalism becomes imaginary. The regime in which models are realizable is, at least, that for which the coefficient is real. The present method does not imply unrealizable solutions when the coefficient is imaginary, but it does guarantee realizability when the coefficient is real; hence, this method provides sufficient, but not necessary, conditions for realizability. Illustrative computations of homogeneous shear flow are presented. It is explained how models can be modified to guarantee realizability in extreme non-equilibrium situations without altering their behaviour in the near-equilibrium regime for which they were formulated.

Sign in / Sign up

Export Citation Format

Share Document