A Procedure for Computation of Fully Stalled Flows in Two-Dimensional Passages

1978 ◽  
Vol 100 (2) ◽  
pp. 180-186 ◽  
Author(s):  
R. L. Woolley ◽  
S. J. Kline
Keyword(s):  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Separated Flows ◽  
Two Dimensional ◽  
Design Problems ◽  
Zonal Model ◽  
Pressure Distributions ◽  
Insight Into ◽  
Critical Aspects ◽  
Two Dimensional Flows

A procedure is described for computation of incompressible, steady, two-dimensional flows in fully-stalled diffusers with plenum exit. The procedure is successful in predicting pressure distributions and patterns to the accuracy of the data. The procedure employs a zonal model; this maintains close connections between the modeling and the physics thereby providing insight into critical aspects of modeling separated flows. The procedure presented is also convenient for computing unstalled flows in passages with turbulent boundary layers for either direct or indirect design problems. Computing times are well within engineering feasibility. The concepts developed can be extended to other classes of separated flows; some of these extensions have already been completed and are referenced.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

Computational Fluid Dynamics Study for Improvement of Prediction of Various Thermally Stratified Turbulent Boundary Layers

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hirofumi Hattori ◽  
Tomoya Houra ◽  
Amane Kono ◽  
Shota Yoshikawa
Keyword(s):  
Boundary Layers ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Eddy Diffusivity ◽  
Turbulent Boundary Layers ◽  
Heat Fluxes ◽  
Shear Stresses ◽  
Turbulent Heat ◽  
Two Dimensional ◽  
Turbulent Statistics

The objectives of this study are to reconstruct a turbulence model of both the large Eddy simulation (LES) and the Reynolds-averaged Navier–Stokes simulation (RANS) which can predict wind synopsis in various thermally stratified turbulent boundary layers over any obstacles. Hence, the direct numerical simulation (DNS) of various thermally stratified turbulent boundary layers with/without forward-step, two-dimensional block, or two-dimensional hill is carried out in order to obtain detailed turbulent statistics for the construction of a database for the evaluation of a turbulence model. Also, DNS clearly reveals the characteristics of various thermally stratified turbulent boundary layers with/without forward-step, two-dimensional block, or two-dimensional hill. The turbulence models employed in LES and RANS are evaluated using the DNS database we obtained. In the LES, an evaluated turbulence model gives proper predictions, but the quantitative agreement of Reynolds shear stress with DNS results is difficult to predict. On the other hand, the nonlinear eddy diffusivity turbulence models for Reynolds stress and turbulent heat flux are also evaluated using DNS results of various thermally stratified turbulent boundary layers over a forward-step in which the turbulence models are evaluated using an a priori method. Although the evaluated models do not make it easy to properly predict the Reynolds shear stresses in all cases, the turbulent heat fluxes can be qualitatively predicted by the nonlinear eddy diffusivity for a heat turbulence model. Therefore, the turbulence models of LES and RANS should be improved in order to adequately predict various thermally stratified turbulent boundary layers over an obstacle.

New Skin Friction and Entrainment Correlations for Turbulent Boundary Layers

1982 ◽  
Vol 104 (4) ◽  
pp. 537-540 ◽  
Author(s):  
J. H. Ferziger ◽  
A. A. Lyrio ◽  
J. G. Bardina
Keyword(s):  
Skin Friction ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Separated Flows ◽  
Entrainment Rate ◽  
New Correlation ◽  
New Skin

A new correlation for the skin friction and two new correlations for the entrainment rate in turbulent boundary layers are presented. Relative to previous correlations, the new ones are at least as accurate, simpler to use, and applicable to separated flows.

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