Some Characteristics of Unsteady Two- and Three-Dimensional Reversed Boundary-Layer Flows

1982 ◽  
pp. 313-323
Author(s):  
H. A. Dwyer ◽  
F. S. Sherman
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Boundary Layer Flows

An Assessment of Three-Dimensional Turbulent Boundary Layer Prediction Methods

1973 ◽  
Vol 95 (3) ◽  
pp. 415-421 ◽  
Author(s):  
A. J. Wheeler ◽  
J. P. Johnston
Keyword(s):  
Boundary Layer ◽  
Eddy Viscosity ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Boundary Layer Flows ◽  
Mean Velocity ◽  
Eddy Viscosity Model ◽  
Separating Flow ◽  
Dimensional Boundary ◽  
Stress Models

Predictions have been made for a variety of experimental three-dimensional boundary layer flows with a single finite difference method which was used with three different turbulent stress models: (i) an eddy viscosity model, (ii) the “Nash” model, and (iii) the “Bradshaw” model. For many purposes, even the simplest stress model (eddy viscosity) was adequate to predict the mean velocity field. On the other hand, the profile of shear stress direction was not correctly predicted in one case by any model tested. The high sensitivity of the predicted results to free stream pressure gradient in separating flow cases is demonstrated.

Three-Dimensional Calculation of Wall Boundary Layer Flows in Turbomachines

1987 ◽  
Author(s):  
W. L. Lindsay ◽  
H. B. Carrick ◽  
J. H. Horlock
Keyword(s):  
Boundary Layer ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Cross Flow ◽  
Flow Profile ◽  
Boundary Layer Flows ◽  
Wall Boundary Layer ◽  
Boundary Layer Development ◽  
Flow Through ◽  
The Cross

An integral method of calculating the three-dimensional turbulent boundary layer development through the blade rows of turbomachines is described. It is based on the solution of simultaneous equations for (i) & (ii) the growth of streamwise and cross-flow momentum thicknesses; (iii) entrainment; (iv) the wall shear stress; (v) the position of maximum cross-flow. The velocity profile of the streamwise boundary layer is assumed to be that described by Coles. The cross-flow profile is assumed to be the simple form suggested by Johnston, but modified by the effect of bounding blade surfaces, which restrict the cross-flow. The momentum equations include expressions for “force-defect” terms which are also based on secondary flow analysis. Calculations of the flow through a set of guide vanes of low deflection show good agreement with experimental results; however, attempts to calculate flows of higher deflection are found to be less successful.

Evaluation of algebraic eddy-viscosity models in three-dimensional turbulent boundary-layer flows

AIAA Journal ◽  
1993 ◽  
Vol 31 (9) ◽  
pp. 1545-1554 ◽  
Author(s):  
M. Semih Olcmen ◽  
Roger L. Simpson
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Eddy Viscosity ◽  
Three Dimensional ◽  
Boundary Layer Flows ◽  
Viscosity Models

scholarly journals Optimal Perturbations in Boundary-Layer Flows Over Rough Surfaces

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
S. Cherubini ◽  
M. D. de Tullio ◽  
P. De Palma ◽  
G. Pascazio
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Base Flow ◽  
Immersed Boundary ◽  
Boundary Layer Flows ◽  
Instability Theory ◽  
Roughness Elements ◽  
Tollmien Schlichting ◽  
Layer Flow ◽  
Lagrangian Optimization

This work provides a three-dimensional energy optimization analysis, looking for perturbations inducing the largest energy growth at a finite time in a boundary-layer flow in the presence of roughness elements. The immersed boundary technique has been coupled with a Lagrangian optimization in a three-dimensional framework. Four roughness elements with different heights have been studied, inducing amplification mechanisms that bypass the asymptotical growth of Tollmien–Schlichting waves. The results show that even very small roughness elements, inducing only a weak deformation of the base flow, can strongly localize the optimal disturbance. Moreover, the highest value of the energy gain is obtained for a varicose perturbation. This result demonstrates the relevance of varicose instabilities for such a flow and shows a different behavior with respect to the secondary instability theory of boundary layer streaks.

scholarly journals APPLICATION OF LES-STOCHASTIC TWO-WAY MODEL TO TWO-PHASE BOUNDARY LAYER FLOWS

2011 ◽  
Vol 1 (32) ◽  
pp. 5
Author(s):  
Yasunori Watanabe ◽  
Yuta Mitobe ◽  
Yasuo Niida ◽  
Ayumi Saruwatari
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Large Scale ◽  
Three Dimensional ◽  
Coupling Model ◽  
Turbulent Energy ◽  
Boundary Layer Flows ◽  
Two Phase ◽  
Eddy Simulation ◽  
Suspension Process

A particle / turbulence two-way coupling model, integrated with conventional stochastic and sub-grid stress models of three-dimensional Large Eddy Simulation (LES), has been applied to the particle-laden turbulent flow in a wave boundary layer developed over seabed with the aim to understand dynamic effects of the particle size and number density to the suspension process in shearing flow over the seabed. While the particle size affects local velocity fluctuations, the particle population significantly induces secondary large-scale flows varying over a scale of the wavelength, and intensifies the turbulent energy near the bed. The particle-induced turbulence may result in additional suspension from the bed, causing a recursive suspension process via the particle turbulence interaction in the boundary layer.

scholarly journals Optimal Perturbations in Boundary Layer Flows Over Rough Surfaces

2012 ◽  
Author(s):  
S. Cherubini ◽  
M. D. de Tullio ◽  
P. De Palma ◽  
G. Pascazio
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Base Flow ◽  
Immersed Boundary ◽  
Boundary Layer Flows ◽  
Instability Theory ◽  
Roughness Elements ◽  
Tollmien Schlichting ◽  
Layer Flow ◽  
Lagrangian Optimization

This work provides a three-dimensional energy optimization analysis, looking for perturbations inducing the largest energy growth at a finite time in a boundary-layer flow in the presence of roughness elements. Amplification mechanisms are described which by-pass the asymptotical growth of Tollmien–Schlichting waves. The immersed boundary technique has been coupled with a Lagrangian optimization in a three-dimensional framework. Two types of roughness elements have been studied, characterized by a different height. The results show that even very small roughness elements, inducing only a weak deformation of the base flow, can strongly localize the optimal disturbance. Moreover, the highest value of the energy gain is obtained for a varicose perturbation, pointing out the importance of varicose instabilities for such a flow and a different behavior with respect to the secondary instability theory of boundary layer streaks.

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