Investigation of 3D Coherent Structures in Turbulent Boundary Layers at High Reynolds Numbers Using MultiPulse-STB

An experimental study was undertaken to investigate the characteristics of turbulent boundary layers developing on smooth flat plate in an open channel flow at moderately high Froude numbers (0.25<Fr<1.1) and low momentum thickness Reynolds numbers 800<Reθ<2900. The low range of Reynolds numbers and the high Froude number range make the study important, as most other studies of this type have been conducted at high Reynolds numbers and lower Froude numbers (∼0.1). Velocity measurements were carried out using a laser-Doppler anemometer equipped with a beam expansion device to enable measurements close to the wall region. The shear velocities were computed using the near-wall measurements in the viscous subregion. The variables of interest include the longitudinal mean velocity, the turbulence intensity, and the velocity skewness and flatness distributions across the boundary layer. The applicability of a constant Coles’ wake parameter (Π=0.55) to open channel flows has been discounted. The effect of the Froude number on the above parameters was also examined.

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Investigations of the Flow in Curved Ducts at Large Reynolds Numbers

Journal of Applied Mechanics ◽

10.1115/1.4009857 ◽

1948 ◽

Vol 15 (4) ◽

pp. 344-348

Author(s):

J. R. Weske

Keyword(s):

Reynolds Number ◽

Pressure Drop ◽

Boundary Layers ◽

Reynolds Numbers ◽

Equation Of Motion ◽

Radius Ratio ◽

High Reynolds Numbers ◽

Net Pressure ◽

High Reynolds ◽

Curved Ducts

Abstract It is found that the flow in curved ducts at high Reynolds numbers may be analyzed by methods adapted from the theory of boundary layers. Integration of the equation of motion of the “shedding layer” led to relations for the net pressure drop of curved ducts as a function of radius ratio and of Reynolds number.

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Rough-Wall Turbulent Boundary Layers

Applied Mechanics Reviews ◽

10.1115/1.3119492 ◽

1991 ◽

Vol 44 (1) ◽

pp. 1-25 ◽

Cited By ~ 794

Author(s):

M. R. Raupach ◽

R. A. Antonia ◽

S. Rajagopalan

Keyword(s):

Boundary Layers ◽

Strong Support ◽

Reynolds Numbers ◽

Viscous Sublayer ◽

Turbulent Boundary Layers ◽

Rough Wall ◽

Roughness Sublayer ◽

Turbulence Structure ◽

Wall Boundary ◽

High Reynolds

This review considers theoretical and experimental knowledge of rough-wall turbulent boundary layers, drawing from both laboratory and atmospheric data. The former apply mainly to the region above the roughness sublayer (in which the roughness has a direct dynamical influence) whereas the latter resolve the structure of the roughness sublayer in some detail. Topics considered include the drag properties of rough surfaces as functions of the roughness geometry, the mean and turbulent velocity fields above the roughness sublayer, the properties of the flow close to and within the roughness canopy, and the nature of the organized motion in rough-wall boundary layers. Overall, there is strong support for the hypothesis of wall similarity: At sufficiently high Reynolds numbers, rough-wall and smooth-wall boundary layers have the same turbulence structure above the roughness (or viscous) sublayer, scaling with height, boundary-layer thickness, and friction velocity.

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High Reynolds number flow between torsionally oscillating disks

Bulletin of the Australian Mathematical Society ◽

10.1017/s0004972700041605 ◽

1970 ◽

Vol 2 (1) ◽

pp. 55-79

Author(s):

K.G. Smith ◽

A.F. Pillow

Keyword(s):

Boundary Layers ◽

Viscous Incompressible Fluid ◽

Reynolds Numbers ◽

Main Body ◽

Low Reynolds Numbers ◽

Reynolds Number Flow ◽

High Reynolds Numbers ◽

Number Flow ◽

High Reynolds ◽

Steady Convection

In this paper the problem solved is that of unsteady flow of a viscous incompressible fluid between two parallel infinite disks, which are performing torsional oscillations about a common axis. The solution is restricted to high Reynolds numbers, and thus extends an earlier solution by Rosenblat for low Reynolds numbers.The solution is obtained by the method of matched asymptotic expansions. In the main body of the fluid the flow is inviscid, but may be rotational, and in the boundary layers adjacent to the disks the non-linear convection terms are small. These two regions do not overlap, and it is found that in order to match the solutions a third region is required in which viscous diffusion is balanced by steady convection. The angular velocity is found to be non-zero only in the boundary layers adjacent to the disks.

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