Spanwise Aspects of Unsteadiness in a Pressure-Induced Turbulent Separation Bubble

2018 ◽  
Author(s):  
Arnaud S. Le Floc'h ◽  
Abdelouahab T. Mohammed-Taifour ◽  
Louis Dufresne ◽  
Julien Weiss
Keyword(s):  
Separation Bubble ◽  
Turbulent Separation

Active Forcing of a Pressure-Induced Turbulent Separation Bubble

2020 ◽  
Author(s):  
Abdelouahab T. Mohammed-Taifour ◽  
Arnaud Le Floc'h ◽  
Julien Weiss
Keyword(s):  
Separation Bubble ◽  
Turbulent Separation

Mean‐velocity scaling in and around a mild, turbulent separation bubble

1995 ◽  
Vol 7 (8) ◽  
pp. 1956-1969 ◽  
Author(s):  
Amy E. Alving ◽  
H. H. Fernholz
Keyword(s):  
Separation Bubble ◽  
Mean Velocity ◽  
Turbulent Separation

Heat Transfer on a Flat Surface Under a Region of Turbulent Separation

1992 ◽  
Author(s):  
R. B. Rivir ◽  
J. P. Johnston ◽  
J. K. Eaton
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Separation Bubble ◽  
Adverse Pressure Gradient ◽  
Constant Heat Flux ◽  
Opposite Wall ◽  
Turbulent Separation ◽  
Full Separation

Fluid dynamics and heat transfer measurements were performed for a separation bubble formed on a smooth, flat, constant-heat-flux plate. The separation was induced by an adverse pressure gradient created by deflection of the opposite wall of the wind tunnel. The heat transfer rate was found to decline monotonically approaching the separation point and reach a broad minimum approximately 60% below zero-pressure-gradient levels. The heat transfer rate increased rapidly approaching reattachment with a peak occuring slightly downstream of the mean reattachment point. The opposite wall shape was varied to reduce the applied adverse pressure gradient. The heat transfer results were similar as long as the pressure gradient was sufficient to cause full separation of the boundary layer.

Numerical study of a turbulent separation bubble with sweep

2019 ◽  
Vol 880 ◽  
pp. 684-706
Author(s):  
G. N. Coleman ◽  
C. L. Rumsey ◽  
P. R. Spalart
Keyword(s):  
Pressure Gradient ◽  
Numerical Study ◽  
Separation Bubble ◽  
Laminar Flows ◽  
Swept Wing ◽  
Mean Velocity ◽  
Independence Principle ◽  
Velocity Magnitude ◽  
Turbulent Separation ◽  
Swept Wings

Direct numerical simulation (DNS) is used to study a separated and rapidly reattached turbulent boundary layer over an idealized $35^{\circ }$ infinite swept wing. The separation and reattachment are induced by a transpiration profile at fixed distance above the layer, with the pressure gradient applied to a well-defined, fully developed, zero-pressure-gradient (ZPG) collateral state. To isolate the influence of the sweep, results are compared with one of our earlier DNS of an unswept flow, with the same chordwise transpiration distribution and appropriate upstream momentum thickness. The independence principle (IP) traditionally proposed for swept wings, which is exact for laminar flows, is found to be close to valid in some regions (bridging the separation/reattachment zone) and to fail in others (in the ZPG layers upstream and downstream of the separation). This is assessed primarily through the skin friction and integral thicknesses. The regions in which the IP is approximately valid correspond to regions of diminished Reynolds-stress divergence, compared to the pressure-gradient magnitude. The mean-velocity profiles exhibit significant skewing as the flow develops, while the velocity magnitude departs only slightly from the ZPG logarithmic profile, even above the separation zone. Implications for Reynolds-averaged turbulence modelling are discussed.

Effect of leading-edge geometry on a turbulent separation bubble

AIAA Journal ◽  
1992 ◽  
Vol 30 (2) ◽  
pp. 559-561 ◽  
Author(s):  
N. Djilali ◽  
I. S. Gartshore
Keyword(s):  
Separation Bubble ◽  
Leading Edge ◽  
Edge Geometry ◽  
Turbulent Separation

Analysis of the Airfoil Stall With a Modification of Viscous-Inviscid Interaction Concept

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
E. L. Amromin
Keyword(s):  
Boundary Layers ◽  
Separation Bubble ◽  
Inviscid Flow ◽  
Reynolds Numbers ◽  
Laminar Separation ◽  
Laminar Boundary Layers ◽  
Integral Methods ◽  
Turbulent Transition ◽  
Turbulent Separation ◽  
Separation Zones

A modification of the viscous-inviscid interaction concept with the employment of coupled vortices around the airfoil wake is introduced for analyzing the airfoil stall. The analyzed flow includes the laminar boundary layers, laminar separation bubble, laminar-turbulent transition zone, turbulent boundary layers, turbulent separation zone, wake, and outer inviscid flow. Integral methods are employed for the boundary layers. The boundaries of separation zones are analyzed as free surfaces, however, their lengths and shapes depend on the Reynolds number. The described modification is validated by a comparison of the numerical results with the previously published experimental data for various airfoils and Reynolds numbers at low Mach numbers. This modification achieves a reasonably good agreement of the computed lift and moment coefficients with their measured values.

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