Author: Ramakrishna BalasubramanianPublisher:
ISBN:
Category : Navier-Stokes equations
Languages : en
Pages : 126
Book Description
Drag Reduction Effects in Turbulent Boundary Layers Over Wavy Walls
Author: Ramakrishna BalasubramanianPublisher:
ISBN:
Category : Navier-Stokes equations
Languages : en
Pages : 126
Book Description
Analytical and Design Techniques for Drag Reduction Studies on Wavy Surfaces
Author: Ramakrishna BalasubramanianPublisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 28
Book Description
Viscous Drag Reduction in Boundary Layers
Author: Publisher: AIAA
ISBN: 9781600863783
Category : Boundary layer
Languages : en
Pages : 542
Book Description
Drag Reduction for Turbulent Boundary Layer Flows Using an Oscillating Wall
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This research program used experimental measurements and computational simulations to study the drag reduction, and the resulting effects on turbulence structure, for a turbulent wall flow subjected to lateral wall oscillations. Major objectives for this study were to establish wall oscillation conditions resulting in maximum drag reduction, and how the turbulence structure was altered so that this drag reduction was attained. Furthermore we were interested in the drag reduction performance over a range of Reynolds numbers, and the onset of the drag reduction at the start of the oscillating wall section, and the decay of drag reduction downstream of the oscillating wall. Our experiments showed the maximum drag reduction for an oscillating wall is 30%. Furthermore, the drag reduction reaches an asymptotic level with increasing wall oscillation velocity, with the maximum level occurring by approximately W sub wp=15. Drag reduction performance was tested for Reynolds numbers of Re theta =500, 950, 1400 and 2400, and the performance was found to be independent of Reynolds number for this range. Experimental and computational studies of the turbulence structure showed the oscillating wall has dramatic effect in practically eliminating the streak structures. Furthermore, the burst and sweep structures were suppressed.
On the Theory of Compliant Wall Drag Reduction in Turbulent Boundary Layers
Author: Robert L. AshPublisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 52
Book Description
Behavior of Turbulent Boundary Layers on Curved Convex Walls
Author: Hans SchmidbauerPublisher:
ISBN:
Category : Mathematics
Languages : en
Pages : 570
Book Description
The system of linear differential equations which indicated the approach of separation and the so-called "boundary-layer thickness" by Gruschwitz is extended in this report to include the case where the friction layer is subject to centrifugal forces. Evaluation of the data yields a strong functional dependence of the momentum change and wall drag on the boundary-layer thickness radius of curvature ratio for the wall. It is further shown that the transition from laminar to turbulent flow occurs at somewhat higher Reynolds Numbers at the convex wall than at the flat plate, due to the stabilizing effect of the centrifugal forces.
Drag of Two-dimensional Small-amplitude Symmetric and Asymmetric Wavy Walls in Turbulent Boundary Layers
Author: John C. LinPublisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 172
Book Description
Aerodynamics for Engineers
Author: John J. BertinPublisher: Cambridge University Press
ISBN: 1009115758
Category : Technology & Engineering
Languages : en
Pages : 843
Book Description
Now reissued by Cambridge University Press, this sixth edition covers the fundamentals of aerodynamics using clear explanations and real-world examples. Aerodynamics concept boxes throughout showcase real-world applications, chapter objectives provide readers with a better understanding of the goal of each chapter and highlight the key 'take-home' concepts, and example problems aid understanding of how to apply core concepts. Coverage also includes the importance of aerodynamics to aircraft performance, applications of potential flow theory to aerodynamics, high-lift military airfoils, subsonic compressible transformations, and the distinguishing characteristics of hypersonic flow. Supported online by a solutions manual for instructors, MATLAB® files for example problems, and lecture slides for most chapters, this is an ideal textbook for undergraduates taking introductory courses in aerodynamics, and for graduates taking preparatory courses in aerodynamics before progressing to more advanced study.
On the Theory of Compliant Wall Drag Reduction in Turbulent Boundary Layers
Author: Robert L. AshPublisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 82
Book Description
Prediction of Compliant Wall Drag Reduction
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781724680730
Category :
Languages : en
Pages : 32
Book Description
A numerical model of turbulent boundary layer flows over compliant walls was investigated. The model is based on Burton's observation that outer flow structures in turbulent boundary layers produce large scale pressure fluctuations near the wall. The results of calculations indicate that certain small wavelength wall motions can have a significant effect upon the stability of turbulent boundary layers. Orszag, S. A. Unspecified Center NASA-CR-3071 NAS1-14906