CONVEX CURVATURE EFFECTS ON THE HEATED TURBULENT BOUNDARY LAYER

1982 ◽  
Author(s):  
Terrence W. Simon ◽  
Robert J. Moffat
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Curvature Effects ◽  
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

Large-eddy simulation of a three-dimensional shear-driven turbulent boundary layer

2000 ◽  
Vol 423 ◽  
pp. 175-203 ◽  
Author(s):  
CHANDRASEKHAR KANNEPALLI ◽  
UGO PIOMELLI
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Turbulent Boundary Layer ◽  
Turbulent Kinetic Energy ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Quasi Equilibrium ◽  
Mean Flow ◽  
Curvature Effects ◽  
Large Eddy

A three-dimensional shear-driven turbulent boundary layer over a flat plate generated by moving a section of the wall in the transverse direction is studied using large-eddy simulations. The configuration is analogous to shear-driven boundary layer experiments on spinning cylinders, except for the absence of curvature effects. The data presented include the time-averaged mean flow, the Reynolds stresses and their budgets, and instantaneous flow visualizations. The near-wall behaviour of the flow, which was not accessible to previous experimental studies, is investigated in detail. The transverse mean velocity profile develops like a Stokes layer, only weakly coupled to the streamwise flow, and is self-similar when scaled with the transverse wall velocity, Ws. The axial skin friction and the turbulent kinetic energy, K, are significantly reduced after the imposition of the transverse shear, due to the disruption of the streaky structures and of the outer-layer vortical structures. The turbulent kinetic energy budget reveals that the decrease in production is responsible for the reduction of K. The flow then adjusts to the perturbation, reaching a quasi-equilibrium three-dimensional collateral state. Following the cessation of the transverse motion, similar phenomena take place again. The flow eventually relaxes back to a two-dimensional equilibrium boundary layer.

Free-Stream Turbulence Effects on Convex-Curved Turbulent Boundary Layers

1989 ◽  
Vol 111 (1) ◽  
pp. 66-72 ◽  
Author(s):  
S. M. You ◽  
T. W. Simon ◽  
J. Kim
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Skin Friction Coefficient ◽  
Radius Of Curvature ◽  
Free Stream Turbulence ◽  
Curvature Effects ◽  
Asymptotic Shape ◽  
Turbulence Effects

Free-stream turbulence intensity effects on a convex-curved turbulent boundary layer are investigated. An attached fully turbulent boundary layer is grown on a flat plate and is then introduced to a downstream section where the test wall is convexly curved, having a constant radius of curvature. Two cases, with free-stream turbulence intensities of 1.85 and 0.65 percent, are discussed. They were taken in the same facility and with the same strength of curvature, δ/R = 0.03−0.045. The two cases have similar flow conditions upon entry to the curve, thus separating the free-stream turbulence effects under study from other effects. The higher turbulence case displayed stronger curvature effects on the skin friction coefficient Cf, and on streamwise-normal and shear stress profiles, than observed in the lower turbulence case. Observations of this are: (1) As expected, the higher turbulence case has a higher Cf value ( ∼ 5 percent) upstream of the curve than does the lower turbulence case, but this difference diminishes by the end of the curve. (2) Streamwise turbulence intensity profiles, differing upstream of the curve for the two cases, are found to be similar near the end of the curve, thus indicating that the effect of curvature is dominating over the effect of free-stream turbulence intensity. Many effects of curvature observed in the lower turbulence intensity case, and reported previously, e.g., a dramatic response to the introduction of curvature and the rapid assumption of an asymptotic shape within the curve, are also seen in the higher turbulence case.

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.

Sign in / Sign up

Export Citation Format

Share Document