scholarly journals Isolating curvature effects in computing wall-bounded turbulent flows

2001 ◽  
Author(s):  
Christopher Rumsey ◽  
Thomas Gatski
Keyword(s):  
Turbulent Flows ◽  
Curvature Effects

scholarly journals Isolating curvature effects in computing wall-bounded turbulent flows

2001 ◽  
Vol 22 (6) ◽  
pp. 573-582 ◽  
Author(s):  
Christopher L. Rumsey ◽  
Thomas B. Gatski ◽  
W. Kyle Anderson ◽  
Eric J. Nielsen
Keyword(s):  
Turbulent Flows ◽  
Curvature Effects

Convex and concave surface curvature effects in wall-bounded turbulent flows

AIAA Journal ◽  
1991 ◽  
Vol 29 (6) ◽  
pp. 895-902 ◽  
Author(s):  
Marshall C. Richmond ◽  
Virendra C. Patel
Keyword(s):  
Turbulent Flows ◽  
Surface Curvature ◽  
Concave Surface ◽  
Curvature Effects

CFD Analysis of the Twin Inclined Injection Flows in an Axi-Symmetric Duct along with Main Turbulent Flow

2014 ◽  
Vol 592-594 ◽  
pp. 1897-1902
Author(s):  
Debajit Saha ◽  
Snehamoy Majumder
Keyword(s):  
Turbulent Flows ◽  
Velocity Variation ◽  
Angle Variation ◽  
Bulk Fluid ◽  
Circular Duct ◽  
Injection Angle ◽  
Curvature Effects ◽  
Mass Injection ◽  
Secondary Injection ◽  
The Impact

A numerical simulation has been carried out to study the effects of twin inclined side mass injection with cross flow through a circular duct using modified model, considering streamline curvature effects by modifying the model constants. 1/7th turbulent velocity profile has been taken at the inlet. The effects of side mass injection on the flow pattern of the main bulk fluid and the mixing of two mutually cross turbulent flows have been studied in details. The formation of recirculatory flow has been visualized by varying the primary as well as secondary injection angle. With the variation of the injection angle axial velocity profiles at various locations and the centerline velocity variation along the duct have been studied. It has been observed that the impact of primary injection angle variation on the recirculation size is more than the secondary injection angle variation.

On Turbulent Flows Dominated by Curvature Effects

1992 ◽  
Vol 114 (1) ◽  
pp. 52-57 ◽  
Author(s):  
G. C. Cheng ◽  
S. Farokhi
Keyword(s):  
Turbulent Flows ◽  
Turbulence Model ◽  
Dominant Role ◽  
Longitudinal Velocity ◽  
Turbulence Models ◽  
Separated Flows ◽  
Local Curvature ◽  
Streamline Curvature ◽  
Curvature Effects ◽  
Numerical Predictions

A technique for improving the numerical predictions of turbulent flows with the effect of streamline curvature is developed. Separated flows and the flow in a curved duct are examples of flow fields where streamline curvature plays a dominant role. New algebraic formulations for the eddy viscosity μt incorporating the k–ε turbulence model are proposed to account for various effects of streamline curvature. The loci of flow reversal (where axial velocities change signs) of the separated flows over various backward-facing steps are employed to test the capability of the proposed turbulence model in capturing the effect of local curvature. The inclusion of the effect of longitudinal curvature in the proposed turbulence model is validated by predicting the distributions of the longitudinal velocity and the static pressure in an S-bend duct and in 180 deg turn-around ducts. The numerical predictions of different curvature effects by the proposed turbulence models are also reported.

Analysis of Streamline Curvature Effects on Wall-Bounded Turbulent Flows

AIAA Journal ◽  
10.2514/2.241 ◽  
1997 ◽  
Vol 35 (8) ◽  
pp. 1273-1279 ◽  
Author(s):  
Jiang Luo ◽  
Budugur Lakshminarayana
Keyword(s):  
Turbulent Flows ◽  
Streamline Curvature ◽  
Curvature Effects

Analysis of Turbulent Flow in 180° Turning Ducts With and Without Guide Vanes

2007 ◽  
Author(s):  
Jiang Luo ◽  
Eli H. Razinsky
Keyword(s):  
Turbulent Flows ◽  
Cross Section ◽  
Flow Separation ◽  
Pressure Loss ◽  
Numerical Study ◽  
Guide Vane ◽  
Outer Wall ◽  
Loss Reduction ◽  
Guide Vanes ◽  
Curvature Effects

This paper presents a numerical study of the turbulent flows through a number of 2-D and 3-D 180° U-ducts, with and without guide vanes, using the Reynolds-averaged Navier-Stokes method. Computations have been first carried out for a 2-D U-duct flow (W/H = 1.0) with four turbulence models (V2F, k-ε, SST and Reynolds stress). The models’ capability for streamline curvature effects on turbulence and separation has been assessed, using flow and turbulence data. The effects of adding a guide vane inside the bend have been analyzed, to reduce/avoid flow separation. Three vanes with different radial locations have been studied, and the mechanism for pressure loss reduction has been examined. Analyses have been performed for turbulent flows in 3-D U-ducts with square cross-section and sharp 180° turning (W/D = 0.2), similar to the U-bends in typical turbine blade cooling passages. The predictions are compared with the data of outer wall pressure. The effects of the guide vane and outer-wall shape on the flow separation, secondary-flow vortices and pressure loss have been evaluated. The combined vane and uniform cross-section area provide a large benefit for the flow distribution and pressure loss reduction.

Prediction of streamline curvature effects on wall-bounded turbulent flows

2000 ◽  
Vol 21 (5) ◽  
pp. 614-619 ◽  
Author(s):  
Nobuyuki Shima ◽  
Takafumi Kawai ◽  
Masayoshi Okamoto ◽  
Ryuta Tsuchikura
Keyword(s):  
Turbulent Flows ◽  
Streamline Curvature ◽  
Curvature Effects

Modified partially averaged Navier–Stokes model for turbulent flow in passages with large curvature

2020 ◽  
Vol 34 (23) ◽  
pp. 2050239
Author(s):  
Weixiang Ye ◽  
Xianwu Luo ◽  
Ying Li
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Turbulence Model ◽  
Navier Stokes ◽  
Small Scale ◽  
Bounded Region ◽  
Rectangular Duct ◽  
Reynolds Stresses ◽  
Curvature Effects ◽  
Text Model

This study presents a partially averaged Navier–Stokes model, MSST PANS, based on a modified SST [Formula: see text] turbulence model to predict turbulent flows with large streamline curvature. The model was validated for turbulent flow in a [Formula: see text] curved rectangular duct (Re = 224,000) to assess the MSST PANS capabilities. The predictions are compared against flow simulations for the same curved rectangular duct using four turbulence models including the standard [Formula: see text] model, SST [Formula: see text] model, [Formula: see text] PANS model and SST [Formula: see text] PANS model. Comparisons among those numerical results and available experimental data show that the MSST PANS model more accurately predicts the velocity components in all three directions, especially in the wall-bounded region than the other models. The study also shows the advantages of the MSST PANS model for predicting the Reynolds stresses, vorticity, and smaller scale turbulent structures in the wall-bounded region not only qualitatively but quantitatively. Furthermore, the MSST PANS model requires fewer computations than the SST PANS model, indicating that this turbulence model, which takes large streamlines curvature effects into consideration, is an effective alternative for capturing the small-scale turbulence flow structures. This turbulence model is expected to be very useful for engineering applications, especially for flows in turbomachinery.

scholarly journals Free-Stream Turbulence and Concave Curvature Effects on Heated, Transitional Boundary Layers

1992 ◽  
Vol 114 (2) ◽  
pp. 338-347 ◽  
Author(s):  
J. Kim ◽  
T. W. Simon ◽  
S. G. Russ
Keyword(s):  
Boundary Layers ◽  
Turbulent Flows ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Dimensional Structure ◽  
Reynolds Analogy ◽  
Free Stream Turbulence ◽  
Curvature Effects ◽  
Concave Wall ◽  
Laminar And Turbulent Flows

An experimental investigation of transition in concave-curved boundary layers at two free-stream turbulence levels (0.6 and 8.6 percent) was performed. For the lower free-stream turbulence intensity case, Go¨rtler vortices were observed in both laminar and turbulent flows using liquid crystal visualization and spanwise velocity and temperature traverses. Transition is thought to occur via a vortex breakdown mode. The vortex locations were invariant with time but were nonuniform across the span in both the laminar and turbulent flows. The upwash regions between two vortices were more unstable than were the downwash regions, containing higher levels of u’ and u’ v’, and lower skin friction coefficients and shape factors. Turbulent Prandtl numbers, measured using a triple-wire probe, were near unity for all post-transitional profiles, indicating no gross violation of Reynolds analogy. No streamwise vortices were observed in the higher turbulence intensity case. This may be due to the high eddy viscosity, which reduces the turbulent Go¨rtler number to subcritical values, thus eliminating the vortices, or due to an unsteadiness of the vortex structure that could not be observed by the techniques used. Based upon these results, predictions that assume two-dimensional modeling of the flow over a concave wall with high free-stream turbulence levels, as on the pressure surface of a turbine blade, seem to be adequate—there is no time-average, three-dimensional structure to be resolved. High levels of free-stream turbulence superimposed on a free-stream velocity gradient (which occurs within curved channels) cause a cross-stream transport of momentum within the flow outside the boundary layer. The total pressure within this region can rise above the value measured at the inlet to the test section.

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