Unsteady Boundary Layer Flows Induced by Accelerating Motion

1974 ◽  
Vol 36 (3) ◽  
pp. 878-883 ◽  
Author(s):  
Masakazu Katagiri
Keyword(s):  
Boundary Layer ◽  
Unsteady Boundary Layer ◽  
Boundary Layer Flows ◽  
Accelerating Motion

Analytical Approach of Unsteady Boundary-Layer Flows Over a Semi-Infinite Plate for All Strouhal Numbers

2010 ◽  
Vol 78 (2) ◽  
Author(s):  
Mohamed Bachiri ◽  
Ahcene Bouabdallah
Keyword(s):  
Boundary Layer ◽  
Strouhal Number ◽  
Boundary Layer Flow ◽  
Ad Hoc ◽  
Infinite Plate ◽  
Unsteady Boundary Layer ◽  
Boundary Layer Flows ◽  
Local Skin ◽  
Analytic Expressions ◽  
Layer Flow

In this paper, the unsteady boundary-layer flow over a semi-infinite flat plate is solved by means of an analytic approach. Via an ad hoc technique based on the boundary-layer flow evolution, an analytic expression of the velocity profile is proposed. The proposed formula verifies well the results given by Rayleigh, Blasius, and Williams–Rhyne for all time, thus for all Strouhal number values, which is the characteristic of the studied problem. As the main results, the local skin friction depending on a Strouhal number is given in an aim to show an explanation on the flow evolutions from the initial solution to the steady solution in the whole spatial region. This approach permits us to take many applications in engineering technology when the analytic expressions of the velocity, temperature, and matter are looked for.

Singularities in solutions of the three-dimensional laminar-boundary-layer equations

1985 ◽  
Vol 160 ◽  
pp. 257-279 ◽  
Author(s):  
James C. Williams
Keyword(s):  
Boundary Layer ◽  
Laminar Boundary Layer ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Unsteady Boundary Layer ◽  
Boundary Layer Flows ◽  
Boundary Layer Equations ◽  
New Type ◽  
Steady Laminar

The three-dimensional steady laminar-boundary-layer equations have been cast in the appropriate form for semisimilar solutions, and it is shown that in this form they have the same structure as the semisimilar form of the two-dimensional unsteady laminar-boundary-layer equations. This similarity suggests that there may be a new type of singularity in solutions to the three-dimensional equations: a singularity that is the counterpart of the Stewartson singularity in certain solutions to the unsteady boundary-layer equations.A family of simple three-dimensional laminar boundary-layer flows has been devised and numerical solutions for the development of these flows have been obtained in an effort to discover and investigate the new singularity. The numerical results do indeed indicate the existence of such a singularity. A study of the flow approaching the singularity indicates that the singularity is associated with the domain of influence of the flow for given initial (upstream) conditions as is prescribed by the Raetz influence principle.

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