Author: Gokul PathikondaPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Inner-outer Interactions in a Rough-wall Turbulent Boundary Layer
Author: Gokul PathikondaTurbulent Boundary Layer Inner-Outer Interactions
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 190
Book Description
A summary of work performed to study the interactions between the inner and outer regions of a turbulent boundary layer is presented. The interactions were studied by observing the response of the boundary layer to different perturbations. The inner region was modified by adding surface roughness, and the outer region suppressed using LEBU's. Velocity measurements were made with a three component LDV, a scanning LDV, and an X-type hot-film probe. The scanning LDV was developed to obtain continuous time history measurements of instantaneous velocity profiles down to y+ = 10. Details of the structure of bursts, sweeps, and shear layers over smooth and rough walls were determined using conditional sampling with simultaneous measurements from a detector probe and a mapping probe. This allowed the mapping of the complete three-dimensional structure of the three-component velocity field for these structures. Both single point detection, using quadrant and VITA techniques, and a unique spatially coherent structure detection technique were used. The spatial detection technique developed in this project takes advantage of the two- dimensional velocity field information obtained from the scanning LDV. Scanning laser doppler velocimeter, Burst, Sweep, Shear layer large scale structure.
On the Interactions Between the Inner and Outer Region Motions in Turbulent Boundary Layers
Author: Joseph Charles KlewickiPublisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 652
Book Description
Rough-Wall Turbulent Boundary Layers
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The objective of this project is to improve our fundamental knowledge of turbulent flows over rough surfaces. Specifically, we hope to investigate the manner in which roughness affects the near-wall drag-producing turbulent structures, and to what extent surface roughness affects the outer part of rough-wall boundary layers. Ultimately we hope to use this knowledge to propose control strategies to reduce momentum loss in rough-wall boundary layers.
A Study of Rough-wall Turbulent Boundary-layer Flows Including Effect of Stagnation Heating
Author: Peeush K. BishnoiThe Turbulent Boundary Layer Rough Wall Pressure Spectrum
Author: M. S. HoweTurbulent Boundary Layer: an Experimental Study of the Transport of Momentum and Heat with the Effect of Roughness
Author: Stanford University. Thermosciences Division. Thermosciences DivisionPublisher:
ISBN:
Category :
Languages : en
Pages : 342
Book Description
IUTAM Symposium on The Physics of Wall-Bounded Turbulent Flows on Rough Walls
Author: T. B. NickelsPublisher: Springer Science & Business Media
ISBN: 9048196310
Category : Technology & Engineering
Languages : en
Pages : 183
Book Description
The study of wall-bounded turbulent ows is of considerable interest from both scienti c and practical view points. As such it has attracted a great deal of research over the last 100 years. Much research has concentratedon ows over smooth walls since these are simpler from experimental, numerical and theoretical standpoints. The ow over rough walls has still received considerable attention but progress has necessarilybeenslower.Perhapsthemostessentialproblem(certainlyfromaprac- cal point of view) is to be able to predict the skin-frictiondrag acting on a plate (or a body) given a certain known roughness characteristic of the surface. Unfortunately this has proved to be very dif cult since even the simplest rough surfaces can be characterised by a number of different parameters and we still cannot directly c- nectthese tothe uiddynamicdragin a givensituation.Varioustheoriesandmodels have been proposed in order to make progress but there is still some disagreement in the community as to the correct understanding of these important ows.
Rough Wall Turbulent Boundary Layers
Author: Anthony Edward PerryPublisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 340
Book Description
The paper describes a detailed experimental study of turbulent boundary layer development over rough walls in both zero and adverse pressure gradients. Skin friction was determined by pressure tapping the roughness elements and measuring their form drag. Two wall roughness geometries were chosen each giving a different law of behaviour. However, it has been found that results for both types of roughness correlate with a Reynolds number based on wall shear velocity and on the distance below the crests of the elements from which the logarithmic distribution of velocity is measured. One important implication of this is that a zero pressure gradient boundary layer with a cavity type rough wall conforms to Rotta's condition of precise self preserving flow. (Author).
The Thermal and Hydrodynamic Behavior of Thick, Rough-wall, Turbulent Boundary Layers
Author: P. M. LigraniPublisher:
ISBN:
Category : Frictional resistance (Hydrodynamics)
Languages : en
Pages : 272
Book Description
Thick, fully rough, and transitionally rough turbulent boundary layers were studied in order to investigate the differences between fully rough and transitionally rough behavior and to observe how downstream development affects these flows as the boundary layers become very thick. Measurements included Stanton numbers, skin friction coefficients, mean temperature and velocity profiles, Reynolds stress tensor component profiles, and spectra of the longitudinal velocity fluctuations. Predictions of wall heat transfer, wall shear, and mean profiles were made using a mixing-length and turbulent Prandtl number closure scheme which accounted for the effects of wall roughness in the boundary layer equations. The turbulent layers were artificially thickened using an array of solid obstacles which produced a two-dimensional equilibrium flow field with properties representative of natural bounday layers, at least up to the level of the turbulent correlations on a smooth wall, and to the level of the spectra of longitudinal velocity fluctuations on a rough wall. A rough-wall boundary layer environment was provided in which all measurements of lower order than the turbulence correlations could be discussed regarding the influence of roughness, and considered to have properties representative of natural behavior. (Author).