scholarly journals Numerical simulation of a three-dimensional non-stationary flow over a blunted cone with a single roughness element with segregation of the boundary layer region

2018 ◽  
Author(s):  
S. V. Kirilovskiy ◽  
T. V. Poplavskaya
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Roughness Element ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Boundary Layer Region ◽  
Layer Region

Some Measurements of a Wake Boundary-Layer Interaction

1962 ◽  
Vol 29 (1) ◽  
pp. 177-180 ◽  
Author(s):  
R. Eichhorn ◽  
T. L. Eddy
Keyword(s):  
Boundary Layer ◽  
Total Pressure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Fluid Flows ◽  
Wake Region ◽  
Boundary Layer Region ◽  
Boundary Layer Interaction ◽  
Layer Flow ◽  
Layer Region

When a strut or other object is attached to a surface along which a fluid flows, the strut disturbs the boundary-layer flow and the wake region of the strut interacts with the boundary layer along the surface giving rise to complicated three-dimensional effects. In the present paper these effects were investigated for a geometry consisting of a 2-in-diam cylinder in uniform axial flow to which was attached normally a 3/16-in-diam dowel forming a strut. The measurements reported include both static and total-pressure surveys in the wake-boundary layer region behind the strut. The resulting wake velocity profiles far from the interaction region behave normally but those within this region do not. The existence of vortexes is in some cases clearly seen.

Three-dimensional boundary layer near the plane of symmetry of a spheroid at incidence

1970 ◽  
Vol 43 (1) ◽  
pp. 187-209 ◽  
Author(s):  
K. C. Wang
Keyword(s):  
Boundary Layer ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Prolate Spheroid ◽  
Boundary Layer Region ◽  
Dimensional Boundary ◽  
The Common ◽  
Implicit Finite Difference ◽  
Layer Region

This paper presents incompressible laminar boundary-layer results on both the leeside and windside of a prolate spheroid. The results are obtained by an implicit finite difference method of the Crank–Nicolson type. Particular attention has been given to the determination of separation and of embedded streamwise vortices. No restriction on the angle of attack or the thickness ratio is imposed, nor are there invoked any of the common assumptions such as similarity, conical flow and others. The results suggest an embedded vortex region existing between the regular boundary-layer region and the separated region. At higher angle of attack, the vortex region becomes so thick that it itself may be more appropriately called ‘separated’ also. The latter possibility leads to questions of applicability for existing theories on three-dimensional separation.

Roughness Element Geometry Required for Wind Tunnel Simulations of the Atmospheric Wind

1977 ◽  
Vol 99 (3) ◽  
pp. 480-485 ◽  
Author(s):  
I. S. Gartshore ◽  
K. A. De Croos
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Wind Tunnel ◽  
Roughness Element ◽  
Three Dimensional ◽  
Wall Stress ◽  
Wide Range ◽  
Drag Plate ◽  
Rough Boundaries ◽  
Single Figure

Using a data correlation for the wall stress associated with very rough boundaries and a semi-empirical calculation method, the shape of boundary layers in exact equilibrium with the roughness beneath them is calculated. A wide range of roughness geometries (two- and three-dimensional elements) is included by the use of equivalent surfaces of equal drag per unit area. Results can be summarized in a single figure which relates the shape factor of the boundary layer (its exponent if it has a power law velocity profile) to the height of the roughness elements and their spacing. New data for one turbulent boundary layer developing over a long fetch of uniform roughness is presented. Wall shear stress, measured directly from a drag plate is combined with boundary layer integral properties to show that the shear stress correlation adopted is reasonably accurate and that the boundary layer is close to equilibrium after passing over a streamwise roughness fetch equal to about 350 times the roughness element height. An example is given of the way in which roughness geometry may be chosen from calculated equilibrium results, for one particular boundary layer thickness and a shape useful for simulating strong atmospheric winds in a wind tunnel.

scholarly journals Receptivity of a laminar boundary layer to the interaction of a three-dimensional roughness element with time-harmonic free-stream disturbances

1992 ◽  
Vol 242 ◽  
pp. 701-720 ◽  
Author(s):  
M. Tadjfar ◽  
R. J. Bodonyi
Keyword(s):  
Boundary Layer ◽  
Laminar Boundary Layer ◽  
Stokes Flow ◽  
Free Stream ◽  
Flow Direction ◽  
Roughness Element ◽  
Three Dimensional ◽  
Unsteady Motion ◽  
Time Harmonic ◽  
Tollmien Schlichting

Receptivity of a laminar boundary layer to the interaction of time-harmonic free-stream disturbances with a three-dimensional roughness element is studied. The three-dimensional nonlinear triple–deck equations are solved numerically to provide the basic steady-state motion. At high Reynolds numbers, the governing equations for the unsteady motion are the unsteady linearized three-dimensional triple-deck equations. These equations can only be solved numerically. In the absence of any roughness element, the free-stream disturbances, to the first order, produce the classical Stokes flow, in the thin Stokes layer near the wall (on the order of our lower deck). However, with the introduction of a small three-dimensional roughness element, the interaction between the hump and the Stokes flow introduces a spectrum of all spatial disturbances inside the boundary layer. For supercritical values of the scaled Strouhal number, S0 > 2, these Tollmien–Schlichting waves are amplified in a wedge-shaped region, 15° to 18° to the basic-flow direction, extending downstream of the hump. The amplification rate approaches a value slightly higher than that of two-dimensional Tollmien–Schlichting waves, as calculated by the linearized analysis, far downstream of the roughness element.

The Effect of Magnetic Field on Compressible Boundary Layer by Homotopy Analysis Method

2021 ◽  
Vol 88 (1-2) ◽  
pp. 125
Author(s):  
R. Madhusudhan ◽  
Achala L. Nargund ◽  
S. B. Sathyanarayana
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Homotopy Analysis Method ◽  
Adverse Pressure Gradient ◽  
Analysis Method ◽  
Boundary Layer Region ◽  
Homotopy Analysis ◽  
Curve Singularities ◽  
Large Injection ◽  
Layer Region

We analyse the effect of applied magnetic field on the flow of compressible fluid with an adverse pressure gradient. The governing partial differential equations are solved analytically by Homotopy analysis method (HAM) and numerically by finite difference method. A detailed analysis is carried out for different values of the magnetic parameter, where suction/ injection is imposed at the wall. It is also observed that flow separation is seen in boundary layer region for large injection. HAM is a series solution which consists of a convergence parameter h which is estimated numerically by plotting <em>h</em> curve. Singularities of the solution are identified by Pade approximation.

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