Effects of Streamwise Vortices on Laminar Boundary-Layer Flow

1968 ◽  
Vol 35 (2) ◽  
pp. 424-426 ◽  
Author(s):  
T. K. Fannelop
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Stokes Equations ◽  
Transverse Velocity ◽  
Three Dimensional ◽  
Perturbation Expansion ◽  
Navier Stokes ◽  
Boundary Layer Equations ◽  
Dimensional Boundary ◽  
Layer Flow

The effects of periodic transverse velocity fluctuations are investigated for boundary-layer flow over a flat plate. The method used is a perturbation expansion of the three-dimensional boundary-layer equations in terms of the small transverse velocity component. The equations are reduced to similarity form by means of suitable transformations. The second-order terms are expressed in terms of the first-order (Blasius) variables and are found to increase linearly with the streamwise coordinate. The present heat-transfer solution agrees with the more qualitative results of Persen. The derived velocity profiles are in exact agreement with the results of Crow’s more elaborate analysis based on the Navier-Stokes equations.

Three-Dimensional Boundary-Layer Flow About an Ablating Slender Cone

1969 ◽  
Vol 91 (4) ◽  
pp. 632-648 ◽  
Author(s):  
T. K. Fannelop ◽  
P. C. Smith
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Cone Angle ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Boundary Layer Equations ◽  
Transverse Curvature ◽  
Dimensional Boundary ◽  
Layer Flow

A theoretical analysis is presented for three-dimensional laminar boundary-layer flow about slender conical vehicles including the effect of transverse surface curvature. The boundary-layer equations are solved by standard finite difference techniques. Numerical results are presented for hypersonic flow about a slender blunted cone. The influences of Reynolds number, cone angle, and mass transfer are studied for both symmetric flight and at angle-of-attack. The effects of transverse curvature are substantial at the low Reynolds numbers considered and are enhanced by blowing. The crossflow wall shear is largely unaffected by transverse curvature although the peak velocity is reduced. A simplified “channel flow” analogy is suggested for the crossflow near the wall.

A Mathematical Study for Three-Dimensional Boundary Layer Flow of Jeffrey Nanofluid

2015 ◽  
Vol 70 (4) ◽  
pp. 225-233 ◽  
Author(s):  
Tasawar Hayat ◽  
Taseer Muhammad ◽  
Sabir Ali Shehzad ◽  
Ahmed Alsaedi
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Mathematical Formulation ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Jeffrey Fluid ◽  
Electrically Conducting ◽  
Boundary Layer Equations ◽  
Dimensional Boundary ◽  
Layer Flow

AbstractIn this article we investigated the characteristics of Brownian motion and thermophoresis in the magnetohydrodynamic (MHD) three-dimensional boundary layer flow of an incompressible Jeffrey fluid. The flow is generated by a bidirectional stretching surface. Fluid is electrically conducting in the presence of a constant applied magnetic field. Mathematical formulation of the considered flow problem is made through the boundary layer analysis. A newly proposed boundary condition requiring zero nanoparticle mass flux is employed in the flow analysis of Jeffrey fluid. The governing nonlinear boundary layer equations are reduced into the nonlinear ordinary differential systems through appropriate transformations. The resulting systems have been solved for the velocities, temperature, and nanoparticle concentration expressions. The contributions of various interesting parameters are studied graphically. The values of the Nusselt number are computed and examined.

Some Examples of Three-Dimensional Effects in Boundary Layer Flow

1954 ◽  
Vol 5 (1) ◽  
pp. 73-84 ◽  
Author(s):  
J. Wilkinson
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Three Dimensional ◽  
Positive Parameter ◽  
Boundary Layer Equations ◽  
Dimensional Effects ◽  
Small Positive Parameter ◽  
Dimensional Boundary ◽  
Layer Flow

SummaryThe three-dimensional boundary layer flow defined by the external irrotational velocity components U = x (ξ), V = αη, where α is a small positive parameter, is investigated with the aid of the boundary layer equations of Howarth. When X(ξ) = ξm a solution exact to the first power in α is found. A Pohlhausen method is then developed for any function x (ξ) and applied to the cases in which x (ξ) = ξm and x (ξ)=i-ξ.

Two-dimensional global low-frequency oscillations in a separating boundary-layer flow

2008 ◽  
Vol 614 ◽  
pp. 315-327 ◽  
Author(s):  
UWE EHRENSTEIN ◽  
FRANÇOIS GALLAIRE
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Perturbation Analysis ◽  
Boundary Layer Flow ◽  
Stokes Equations ◽  
Low Frequency ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Optimal Perturbation ◽  
Layer Flow

A separated boundary-layer flow at the rear of a bump is considered. Two-dimensional equilibrium stationary states of the Navier–Stokes equations are determined using a nonlinear continuation procedure varying the bump height as well as the Reynolds number. A global instability analysis of the steady states is performed by computing two-dimensional temporal modes. The onset of instability is shown to be characterized by a family of modes with localized structures around the reattachment point becoming almost simultaneously unstable. The optimal perturbation analysis, by projecting the initial disturbance on the set of temporal eigenmodes, reveals that the non-normal modes are able to describe localized initial perturbations associated with the large transient energy growth. At larger time a global low-frequency oscillation is found, accompanied by a periodic regeneration of the flow perturbation inside the bubble, as the consequence of non-normal cancellation of modes. The initial condition provided by the optimal perturbation analysis is applied to Navier–Stokes time integration and is shown to trigger the nonlinear ‘flapping’ typical of separation bubbles. It is possible to follow the stationary equilibrium state on increasing the Reynolds number far beyond instability, ruling out for the present flow case the hypothesis of some authors that topological flow changes are responsible for the ‘flapping’.

Sign in / Sign up

Export Citation Format

Share Document