Calculations of heat transfer in stagnation flow regions by using second-moment closure models in conjunction with the new general wall treatment

2010 ◽  
Vol 10 (4) ◽  
pp. 246
Author(s):  
B. Basara
Keyword(s):  
Heat Transfer ◽  
Moment Closure ◽  
Stagnation Flow ◽  
Second Moment ◽  
Closure Models ◽  
Second Moment Closure

Computation of Flow and Heat Transfer in Two-Pass Channels With 60 deg Ribs

2001 ◽  
Vol 123 (3) ◽  
pp. 563-575 ◽  
Author(s):  
Yong-Jun Jang ◽  
Hamn-Ching Chen ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Moment Closure ◽  
Closure Model ◽  
Second Moment ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Sharp Turn ◽  
Second Moment Closure ◽  
Near Wall

Numerical predictions of three-dimensional flow and heat transfer are presented for a two-pass square channel with and without 60 deg angled parallel ribs. Square sectioned ribs were employed along one side surface. The rib height-to-hydraulic diameter ratio e/Dh is 0.125 and the rib pitch-to-height ratio (P/e) is 10. The computation results were compared with the experimental data of Ekkad and Han [1] at a Reynolds number (Re) of 30,000. A multi-block numerical method was used with a chimera domain decomposition technique. The finite analytic method solved the Reynolds-Averaged Navier Stokes equation in conjunction with a near-wall second-order Reynolds stress (second-moment) closure model, and a two-layer k-ε isotropic eddy viscosity model. Comparing the second-moment and two-layer calculations with the experimental data clearly demonstrated that the angled rib turbulators and the 180 deg sharp turn of the channel produced strong non-isotropic turbulence and heat fluxes, which significantly affected the flow fields and heat transfer coefficients. The near-wall second-moment closure model provides an improved heat transfer prediction in comparison with the k-ε model.

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
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