The laminar wall-jet over a curved surface

1968 ◽  
Vol 31 (3) ◽  
pp. 459-465 ◽  
Author(s):  
I. J. Wygnanski ◽  
F. H. Champagne
Keyword(s):  
Laminar Flow ◽  
Velocity Profile ◽  
Skin Friction ◽  
Surface Pressure ◽  
Similarity Solution ◽  
Plane Surface ◽  
Curved Surface ◽  
Radius Of Curvature ◽  
Wall Jet ◽  
The One

The laminar flow of a wall jet over a curved surface is considered. A unique similarity solution is obtained for both concave and convex surfaces when the local radius of curvature is proportional to x3/4. This solution satisfies a similar invariant condition to the one derived by Glauert for the wall jet over a plane surface. The variation of the shape of the velocity profile, the skin friction, and the surface pressure as a function of curvature is given.

Laminar Wall Jet of a Non-Newtonian Fluid Over a Curved Surface

1984 ◽  
Vol 51 (2) ◽  
pp. 440-443 ◽  
Author(s):  
Rama Subba Reddy Gorla
Keyword(s):  
Friction Coefficient ◽  
Velocity Field ◽  
Newtonian Fluid ◽  
Similarity Solution ◽  
Skin Friction Coefficient ◽  
Curved Surface ◽  
Wall Jet ◽  
Two Dimensional ◽  
Special Shape ◽  
Curvature Parameter

An analysis is presented for the flow of a laminar, two-dimensional, incompressible, non-Newtonian fluid jet flowing over a curved surface. A unique similarity solution is obtained for both concave and convex surfaces. The similarity solution requires a special shape of the curved surface which is also determined. Numerical results are presented for the details of the velocity field and skin friction coefficient as a function of the curvature parameter.

On a turbulent wall jet flowing over a circular cylinder

1999 ◽  
Vol 381 ◽  
pp. 1-25 ◽  
Author(s):  
R. NEUENDORF ◽  
I. WYGNANSKI
Keyword(s):  
Circular Cylinder ◽  
Surface Pressure ◽  
Angular Position ◽  
Adverse Pressure Gradient ◽  
Radius Of Curvature ◽  
Wall Jet ◽  
Mean Flow ◽  
Potential Core ◽  
Rate Of Spread ◽  
Turbulent Wall

The effect of surface curvature on the development of a two-dimensional wall jet was investigated experimentally. A comparison was made between a wall jet flowing around a circular cylinder and its plane equivalent. Velocity surveys and surface pressure measurements in the curved wall jet suggest the existence of two primary regions of interest. The first region, ranging from the end of the potential core to an approximate angular position of θ=120°, is characterized by a constant surface pressure and a self similarity of the mean flow. The second region is marked by an adverse pressure gradient leading to separation around θ=230°. The rate of spread of this flow, even in the initial region, is much higher than in the plane wall jet and so are the levels of turbulence and Reynolds stress. The dominant lengthscale in this flow is the radius of curvature R and the dominant velocity scale is the square root of the kinematic jet momentum divided by the radius of curvature. Entrainment of ambient fluid which causes the jet to adhere to the curved surface is also the main reason for its separation which is preceded by a rapid rate of spread of the flow leading to the failure of the boundary-layer approximation.

Complete Velocity Profile and “Optimum” Skin Friction Formulas for the Plane Wall-Jet

1982 ◽  
Vol 104 (1) ◽  
pp. 59-65 ◽  
Author(s):  
G. P. Hammond
Keyword(s):  
Velocity Profile ◽  
Skin Friction ◽  
Initial Conditions ◽  
Jet Flows ◽  
Wall Jet ◽  
Wall Region ◽  
Law Of The Wall ◽  
Single Formula ◽  
Turbulent Wall ◽  
Good Agreement

An analytic expression for the complete velocity profile of a plane, turbulent wall-jet in “stagnant” surroundings is obtained by coupling Spalding’s single formula for the inner layer with a sine function for the “wake component.” This expression is transformed at the velocity maxima to yield an “optimum log-law” for skin friction. An approximate skin friction formula based on the “initial conditions” of the wall-jet is also presented. The formulas are generally in good agreement with experimental data. The complete velocity profile does not exhibit the conventional “law of the wall” behavior and modifications are consequently recommended to the usual treatment of the near-wall region in numerical calculation procedures for wall-jet flows. The use of the “Clauser plot” method of skin friction measurement is similarly shown to be in error when applied to wall-jets.

Convective diffusion toward the sphere in laminar flow around the sphere

1979 ◽  
Vol 44 (4) ◽  
pp. 1218-1238
Author(s):  
Arnošt Kimla ◽  
Jiří Míčka
Keyword(s):  
Laminar Flow ◽  
Velocity Profile ◽  
Peclet Number ◽  
Convective Diffusion ◽  
Péclet Number ◽  
Stability Of The Solution

The problem of convective diffusion toward the sphere in laminar flow around the sphere is solved by combination of the analytical and net methods for the region of Peclet number λ ≥ 1. The problem was also studied for very small values λ. Stability of the solution has been proved in relation to changes of the velocity profile.

scholarly journals Effect of Differential Speed Rotation Technology on the Forming Uniformity in Flexible Rolling Process

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1906 ◽  
Author(s):  
Yi Li ◽  
Mingzhe Li ◽  
Kai Liu ◽  
Zhuo Li
Keyword(s):  
Element Model ◽  
Rolling Process ◽  
Metal Plate ◽  
Curved Surface ◽  
Forming Process ◽  
Surface Part ◽  
Flexible Rolling ◽  
Speed Rotation ◽  
The One ◽  
Differential Speed

As the local forming non-uniform of the formed curved surface part with larger bending deformation is the one of common defects, the utilization ratio of metal plate greatly reduces due to this defect, and cost of production is also increasing. In this paper, the differential speed rotation technology of flexible rolling process was proposed firstly to solve this forming defect. The finite element model was established, the reason of the local forming non-uniform was discussed; the effect of differential speed rotation technology on the forming uniform was studied. The results show that: Flexible rolling is a process based on thickness reduction, in this forming process, the thickness reduces sharply near the back end of metal plate, the local forming non-uniform of formed curved surface part is caused during this process; the differential speed rotation technology is applied in flexible rolling, with increasing rotation speed difference between upper and lower roll set, the forming uniformity of the formed curved surface part is greatly improved. The results of numerical simulation are in agreement with the result of forming experiments.

Laminar flow in symmetrical channels with slightly curved walls II. An asymptotic series for the stream function

1963 ◽  
Vol 272 (1350) ◽  
pp. 406-428 ◽  
Keyword(s):  
Laminar Flow ◽  
Asymptotic Series ◽  
Radius Of Curvature ◽  
Two Dimensional ◽  
The Third ◽  
Higher Order Terms ◽  
Curvature Parameter ◽  
Leading Term ◽  
Flow Through ◽  
Curved Walls

A class of two-dimensional channels, with walls whose radius of curvature is uniformly large relative to local channel width, is described, and the velocity field of laminar flow through these channels is obtained as a power series in the small curvature parameter. The leading term is the Jeffery-Hamel solution considered in part I, and it is shown here how the higher-order terms are found. Terms of the third approximation have been computed. The theory is applied to two examples, for one of which experimental results are available and confirm the theoretical values with fair accuracy.

scholarly journals An Invariant Three-polar Representation for R3 Surfaces: Robustness and Accuracy for 3D Faces Description

2021 ◽  
Vol 15 ◽  
pp. 56-61
Author(s):  
Majdi Jribi ◽  
Faouzi Ghorbel
Keyword(s):  
Hausdorff Distance ◽  
Reference Points ◽  
Curved Surface ◽  
Surface Representation ◽  
Level Curves ◽  
Polar Representation ◽  
The Mean ◽  
Invariant Points ◽  
The One ◽  
Human Faces

In this paper, we intend to introduce a new curved surface representation that we qualify by three-polar. It is constructed by the superposition of the three geodesic potentials generated from three reference points of the surface. By considering a pre-selected levels set of this superposition, invariant points are obtained. The accuracy of the three-polar representation for 3D human faces description is performed in the mean of the Hausdorff distance. A comparison between this representation and the one based on the level curves around the nose tip is established in the sense of the robustness under errors on the nose tip positions.

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