The relaxation of a turbulent boundary layer far downstream of a short region of convex curvature

1987 ◽  
Author(s):  
AMY ALVING ◽  
JONATHAN WATMUFF ◽  
ALEXANDER SMITS
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Short Region ◽  
Convex Curvature

The impact of streamwise convex curvature on the supersonic turbulent boundary layer

2017 ◽  
Vol 29 (11) ◽  
pp. 116106 ◽  
Author(s):  
Qian-cheng Wang ◽  
Zhen-guo Wang ◽  
Yu-xin Zhao
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Convex Curvature ◽  
The Impact

Turbulent boundary layer relaxation from convex curvature

1990 ◽  
Vol 211 ◽  
pp. 529-556 ◽  
Author(s):  
Amy E. Alving ◽  
Alexander J. Smits ◽  
Jonathan H. Watmuff
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Large Scale ◽  
Stable State ◽  
Relaxation Behaviour ◽  
Mean Flow ◽  
Mean Velocity ◽  
Measuring Station ◽  
The Mean ◽  
Convex Curvature

A study was undertaken to examine the flat plate relaxation behaviour of a turbulent boundary layer recovering from 90° of strong convex curvature (δ0/R = 0.08), for a length of ≈ 90δ0 after the end of curvature, where δ0 is the boundary layer thickness at the start of the curvature. The results show that the relaxation behaviour of the mean flow and the turbulence are quite different. The mean velocity profile and skin friction coefficient asymptotically approach the unperturbed state and at the last measuring station appear to be fully recovered. The turbulence relaxation, however, occurs in several stages over a much longer distance. In the first stage, a stress ‘bore’ (a region of elevated stress) is generated near the wall, and the bore thickens with distance downstream. Eventually it fills the whole boundary layer, but the stress levels continue to rise beyond their self-preserving values. Finally the stresses begin a gradual decline, but at the last measuring station they are still well above the unperturbed levels, and the ratios of the Reynolds stresses are distorted. These results imply a reorganization of the large-scale structure into a new quasi-stable state. The long-lasting effects of curvature highlight the sensitivity of a boundary layer to its condition of formation.

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