scholarly journals Unsteady Boundary Layers : 3rd Report, Boundary Layer on a Circular Cylinder in Rotational Oscillation

1962 ◽  
Vol 5 (17) ◽  
pp. 64-72 ◽  
Author(s):  
Eiichi HORI
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Boundary Layers ◽  
Rotational Oscillation ◽  
Unsteady Boundary Layers

An experimental and computational study of the post-collisional flow induced by an impulsively rotated sphere

2019 ◽  
Vol 881 ◽  
pp. 772-793 ◽  
Author(s):  
Sophie A. W. Calabretto ◽  
James P. Denier ◽  
Benjamin Levy
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Boundary Layers ◽  
Recirculation Zone ◽  
Particle Image ◽  
Computational Study ◽  
Collision Process ◽  
Image Velocimetry ◽  
Unsteady Boundary Layers ◽  
Quiescent Fluid

The unsteady flow due to a sphere, immersed in a quiescent fluid, and suddenly rotated, is a paradigm for the development of unsteady boundary layers and their collision. Such a collision arises when the boundary layers on the surface of the sphere are advected towards the equator, where they collide, serving to generate a radial jet. We present the first particle image velocimetry measurements of this collision process, the resulting starting vortex and development of the radial jet. Coupled with new computations, we demonstrate that the post-collision steady flow detaches smoothly from the sphere’s surface, in qualitative agreement with the analysis of Stewartson (Grenzschichtforschung/Boundary Layer Research (ed. H. Görtler), Springer, 1958, pp. 60–70), with no evidence of a recirculation zone, contrary to the conjectured structure of Smith & Duck (Q. J. Mech. Appl. Maths, vol. 20, 1977, pp. 143–156).

Approximate Methods of Solving the Laminar Boundary-Layer Equations

1962 ◽  
Vol 13 (3) ◽  
pp. 285-290 ◽  
Author(s):  
R. M. Terrill
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Skin Friction ◽  
Boundary Layers ◽  
Laminar Boundary Layer ◽  
Numerical Solutions ◽  
Approximate Methods ◽  
Boundary Layer Equations ◽  
Laminar Boundary Layers ◽  
Remarkable Agreement

SummaryCurie and Skan have modified the approximate methods of Thwaites and Stratford to predict separation properties of laminar boundary layers for flow over an impermeable surface. The work of Curie and Skan has been extended by Curle to include the estimation of laminar skin friction for the whole flow. The purpose of the following note is to compare the approximate methods of Curie and Skan and Curle with the numerical results given by the author for flow past a circular cylinder. It is found that there is remarkable agreement between these approximate methods and the exact numerical solutions. This indicates that these methods can be used widely, both on account of their simplicity and their accuracy.

Unsteady Boundary Layers on a Flat Plate Disturbed by Periodic Wakes: Part II—Measurements of Unsteady Boundary Layers and Discussion

1996 ◽  
Vol 118 (2) ◽  
pp. 337-344 ◽  
Author(s):  
K. Funazaki
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Boundary Layers ◽  
Time Domain ◽  
Indirect Effect ◽  
Transition Model ◽  
Hot Wire ◽  
Turbulent Spot ◽  
Boundary Layer Interaction ◽  
Unsteady Boundary Layers

As the second part of the study, detailed hot-wire anemometry measurements of wake-affected boundary layers on the flat plate are made. These measurements are organized in order, first, to check the standpoint of the modeling of the wake-induced transition proposed in Part I, and second, to observe wake–boundary layer interaction in detail from a viewpoint of direct and indirect effect of the wake passage upon turbulent spot generation within the boundary layer, as described by Walker (1993). The validity of the presumed state of the wake-affected boundary layer in the distance–time domain, which constitutes the basis of the transition model, is confirmed to great extent. However, it is also found that the criterion for the onset of the wake-induced transition adopted in Part I should be reconsidered. Some successful attempts are therefore made to specify the transition onset.

Unsteady boundary layers with an intelligent numerical scheme

1986 ◽  
Vol 163 ◽  
pp. 129-140 ◽  
Author(s):  
Tuncer Cebeci
Keyword(s):  
Circular Cylinder ◽  
Boundary Layers ◽  
Numerical Scheme ◽  
Local Velocity ◽  
Time Step ◽  
Box Scheme ◽  
Unsteady Boundary Layers ◽  
Eulerian Methods ◽  
Large Flow ◽  
Method Show

A numerical method has been developed to represent unsteady boundary layers with large flow reversal. It makes use of the characteristic box scheme which examines the finite-difference grid in relation to the magnitude and direction of local velocity and reaches and implements a decision to ensure that the Courant, Friedricks & Lewey stability criterion is not violated. The method has been applied to the problem of an impulsively started circular cylinder and the results, though generally consistent with those of van Dommelen & Shen obtained with a Lagrangian method, show some differences. The time step is identified as very important and, with the present intelligent numerical scheme, the results were readily extended to times far beyond those previously achieved with Eulerian methods. Extrapolation of the results suggests that the much-discussed singularity for this unsteady flow is the same as that of the corresponding steady flow.

The Form Drag of Three-Dimensional Bluff Bodies Immersed in Turbulent Boundary Layers

1982 ◽  
Vol 104 (3) ◽  
pp. 326-333 ◽  
Author(s):  
H. Sakamoto ◽  
M. Moriya ◽  
S. Taniguchi ◽  
M. Arie
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Boundary Layers ◽  
Bluff Body ◽  
Three Dimensional ◽  
Turbulent Boundary Layers ◽  
Bluff Bodies ◽  
Smooth Wall ◽  
Form Drag ◽  
Pressure Distributions

Measurements of the pressure distributions on the three-dimensional bluff bodies are correlated with the characteristics of the smooth-wall turbulent boundary layers in which the bodies are immersed. The bluff bodies selected for measurement were a cube and a vertical circular cylinder which can be considered as typical examples of three-dimensional bluff bodies. Experimental data were collected to investigate the effects of (1) the variation of the height of bluff bodies h, (2) the characteristics of the smooth-wall boundary layers in which they are immersed, on the form drag acting on the three-dimensional bluff bodies. For flow with zero-pressure gradient, the form drag coefficients of the cube and the vertical circular cylinder defined by CDτ=D/(1/2ρuτ2h2) are found to be expressed as a power-law function of huτ/ν in the range of h/δ less than about 1.0, where D is the form drag, uτ the shear velocity, ν the kinematic viscosity and δ the thickness of the undisturbed boundary layer at the location of the bluff bodies. For h/δ>1.0, the drag coefficients are independent of the parameter uτ/U0, being uniquely related to h/δ. Further, the pressure distributions along the front centerline of each bluff body can be expressed by a single curve irrespective of both the height of the bluff body and the boundary layer characteristics and show a good agreement with the dynamic pressure in an undisturbed boundary layer at the location of the bluff bodies in the range of about 0.2<y/h<0.7, where y is the distance from the wall.

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