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Boundary layer control
About: Boundary layer control is a research topic. Over the lifetime, 5302 publications have been published within this topic receiving 107643 citations.
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TL;DR: In this article, the authors describe the formation of low-speed streaks in the region very near the wall, which interact with the outer portions of the flow through a process of gradual lift-up, then sudden oscillation, bursting, and ejection.
Abstract: Extensive visual and quantitative studies of turbulent boundary layers are described. Visual studies reveal the presence of surprisingly well-organized spatially and temporally dependent motions within the so-called ‘laminar sublayer’. These motions lead to the formation of low-speed streaks in the region very near the wall. The streaks interact with the outer portions of the flow through a process of gradual ‘lift-up’, then sudden oscillation, bursting, and ejection. It is felt that these processes play a dominant role in the production of new turbulence and the transport of turbulence within the boundary layer on smooth walls.Quantitative data are presented providing an association of the observed structure features with the accepted ‘regions’ of the boundary layer in non-dimensional co-ordinates; these data include zero, negative and positive pressure gradients on smooth walls. Instantaneous spanwise velocity profiles for the inner layers are given, and dimensionless correlations for mean streak-spacing and break-up frequency are presented.Tentative mechanisms for formation and break-up of the low-speed streaks are proposed, and other evidence regarding the implications and importance of the streak structure in turbulent boundary layers is reviewed.
2,753 citations
Book•
06 Jan 1994
TL;DR: In this paper, Spectra and cospectra over flat uniform terrain, Flow over plant canopies and Flow over changing terrain are used to observe the boundary layer of a plant canopy.
Abstract: 1 Flow over flat uniform terrain 2 Spectra and cospectra over flat uniform terrain 3 Flow over plant canopies 4 Flow over changing terrain 5 Flow over hills 6 Sensors and techniques for observing the boundary layer 7 Acquisition and processing of boundary layer data Index
1,791 citations
TL;DR: In this article, the authors examined the effect of roughness on boundary layer characteristics and showed that the wall is aerodynamically smooth for a turbulent boundary layer if the roughness elements are so small as to be buried in the laminar sublayer.
Abstract: Publisher Summary This chapter discusses the simple case of the turbulent boundary layer in a constant pressure field and considers the complex problem of the effects of pressure gradients, and variable wall roughness The concepts of boundary layer phenomena, in general, and turbulent boundary layers, in particular, have found application in a wide range of fields including aeronautics, guided missiles, marine engineering, hydraulics, meteorology, oceanography, chemical engineering, atomic reactors, and the flow of liquids and gases in the human body Many ideas for turbulent boundary layers involve assumptions other than those for turbulent shear stresses and in these cases, the validity of the results is examined first for laminar layers and then interpreted in the light of the possible shear stress patterns of turbulent layers The effect of roughness on boundary layer characteristics is examined in the chapter The wall is aerodynamically smooth for a turbulent boundary layer if the roughness elements are so small as to be buried in the laminar sublayer Pressure gradients, Reynolds number, or roughness does not affect the constants of proportionality The assumption of a constant outer viscosity has been investigated only for the case of equilibrium layers
1,367 citations
TL;DR: In this article, the authors propose a method for customizing a page view by dragging and re-positioning the boxes below the boxes. But this method is limited to a single page view.
Abstract: Related Content Customize your page view by dragging and repositioning the boxes below. Related Journal Articles
1,229 citations