Transverse curvature effects in turbulent boundary layer

1999 ◽  
Vol 35 (7) ◽  
pp. 661-672 ◽  
Author(s):  
J. Piquet ◽  
V.C. Patel
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Curvature Effects ◽  
Transverse Curvature

Effect of Transverse Curvature on Turbulent-Boundary-Layer Characteristics

1958 ◽  
Vol 2 (04) ◽  
pp. 33-51
Author(s):  
Yun-Sheng Yu
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Turbulent Boundary Layer ◽  
Velocity Profile ◽  
Pressure Gradient ◽  
Boundary Layer Thickness ◽  
Axial Flow ◽  
Shearing Stress ◽  
Transverse Curvature ◽  
Similarity Laws

Tests made on the turbulent boundary layer on a circular cylinder in axial flow at zero pressure gradient are described. From the measurements, similarity laws of the velocity profile are formulated, and various boundary-layer characteristics are evaluated and compared with the flatplate results. It is found that the effect of transverse curvature is to increase the surface shearing stress and to decrease the boundary-layer thickness, and that the latter variation is more pronounced than the former.

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.

Effect of transverse curvature on turbulent boundary-layer mass transfer

AIChE Journal ◽  
1970 ◽  
Vol 16 (4) ◽  
pp. 694-695 ◽  
Author(s):  
S. S. Chen
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Turbulent Boundary Layer ◽  
Transverse Curvature

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.

Experiments on a turbulent cylindrical wall jet

1967 ◽  
Vol 29 (3) ◽  
pp. 495-512 ◽  
Author(s):  
J. B. Starr ◽  
E. M. Sparrow
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Mixing Layer ◽  
Velocity Profiles ◽  
Viscosity Data ◽  
Wall Jet ◽  
Cylindrical Wall ◽  
Law Of The Wall ◽  
Curvature Effects ◽  
Transverse Curvature

The investigation described here is an experimental study directed toward determining flow field and surface friction characteristics of a cylindrical wall jet. The flow configuration is obtained by placing a cylindrical rod along the axis of a converging nozzle. The flow field thus produced consists of a developing turbulent boundary layer co-existing with an outer fluid layer that mixes freely with quiescent surroundings. Direct measurements of fluid friction at the rod surface, performed with a hot-film element, revealed a significant effect of transverse surface curvature on the local friction factor. Velocity profiles at various axial stations exhibited similarity in the outer mixing layer, but not in the boundary layer adjacent to the surface. Representations of the velocity field in terms of law of the wall variables and defect-law variables revealed significant transverse curvature effects. The measured wall-jet velocity profiles could be satisfactorily represented in terms of a law of the wake, wherein the wake function depends on a transverse curvature parameter. In the outer mixing layer, the eddy viscosity data correspond closely to those of free jets.

Wall pressure and coherent structures in a turbulent boundary layer on a cylinder in axial flow

1995 ◽  
Vol 286 ◽  
pp. 137-171 ◽  
Author(s):  
Stephen R. Snarski ◽  
Richard M. Lueptow
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Large Scale ◽  
Streamwise Velocity ◽  
Wall Pressure ◽  
Small Scale ◽  
Fluctuating Pressure ◽  
Large Scale Structures ◽  
Transverse Curvature ◽  
Scale Structures

Measurements of wall pressure and streamwise velocity fluctuations in a turbulent boundary layer on a cylinder in an axial air flow (δ/a = 5.04, Reθ = 2870) have been used to investigate the turbulent flow structures in the cylindrical boundary layer that contribute to the fluctuating pressure at the wall in an effort to deduce the effect of transverse curvature on the structure of boundary layer turbulence. Wall pressure was measured at a single location with a subminiature electret condenser microphone, and the velocity was measured throughout a large volume of the boundary layer with a hotwire probe. Auto- and cross-spectral densities, cross-correlations, and conditional sampling of the pressure and streamwise velocity indicate that two primary groups of flow disturbances contribute to the fluctuating pressure at the wall: (i) low-frequency large-scale structures with dynamical significance across the entire boundary layer that are consistent with a pair of large-scale spanwise-oriented counter-rotating vortices and (ii) higher frequency small-scale disturbances concentrated close to the wall that are associated with the burst-sweep cycle and are responsible for the short-duration large-amplitude wall pressure fluctuations. A bidirectional relationship was found to exist between both positive and negative pressure peaks and the temporal derivative of u near the wall. Because the frequency of the large-scale disturbance observed across the boundary layer is consistent with the bursting frequency deduced from the average time between bursts, the burst-sweep cycle appears to be linked to the outer motion. A stretching of the large-scale structures very near the wall, as suggested by space-time correlation convection velocity results, may provide the coupling mechanism. Since the high-frequency disturbance observed near the wall is consistent with the characteristic frequency deduced from the average duration of bursting events, the bursting process provides the two characteristic time scales responsible for the bimodal distribution of energy near the wall. Because many of the observed structural features of the cylindrical boundary layer are similar to those observed in flat-plate turbulent boundary layers, transverse curvature appears to have little effect on the fundamental turbulent structure of the boundary layer for the moderate transverse curvature ratio used in this investigation. From differences that exist between the turbulence intensity, skewness, and spectra of the streamwise velocity, however, it appears that transverse curvature may enhance (i.e. energize) the large-scale motion owing to the reduced constraint imposed on the flow by the smaller cylindrical wall.

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