The prediction of laminarization with a two-equation model of turbulence

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.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022112067001740

The structure of turbulent boundary layers

Handbook of Numerical Heat Transfer Free Full Download Links from Multiple Mirrors added by DL4W on 2015-04-10 02:13:35. Handbook of heat transfer / editors, W.M. Rohsenow, J.P. Hartnett. Y.I. Cho. m 3rd ed. p. cm. Includes bibliographical references and index. ISBN 0-07053555-8. Students investigate heat transfer by conduction, convection and radiation. The analogy between heat and mass transfer is covered and applied in the analysis.

Handbook of heat transfer

Laser-Doppler measurements of velocity distribution and reattachment length are reported downstream of a single backward-facing step mounted in a two-dimensional channel. Results are presented for laminar, transitional and turbulent flow of air in a Reynolds-number range of 70 < Re < 8000. The experimental results show that the various flow regimes are characterized by typical variations of the separation length with Reynolds number. The reported laser-Doppler measurements do not only yield the expected primary zone of recirculating flow attached to the backward-facing step but also show additional regions of flow separation downstream of the step and on both sides of the channel test section. These additional separation regions have not been previously reported in the literature.Although the high aspect ratio of the test section (1:36) ensured that the oncoming flow was fully developed and two-dimensional, the experiments showed that the flow downstream of the step only remained two-dimensional at low and high Reynolds numbers.The present study also included numerical predictions of backward-facing step flow. The two-dimensional steady differential equations for conservation of mass and momentum were solved. Results are reported and are compared with experiments for those Reynolds numbers for which the flow maintained its two-dimensionality in the experiments. Under these circumstances, good agreement between experimental and numerical results is obtained.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022112083002839

Experimental and Theoretical Investigation of Backward-Facing Step Flow

Proposals are made for modelling the pressure-containing correlations which appear in the transport equations for Reynolds stress and heat flux in a simple way which accounts for gravitational effects and the modification of the fluctuating pressure field by the presence of a wall. The predicted changes in structure are shown to agree with Young's (1975) measurements in a free stratified shear flow and with the Kansas data on the atmospheric surface layer.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022112078001251

Ground effects on pressure fluctuations in the atmospheric boundary layer

We examine critically the presently available experimental data on Turbulent Prandtl Number for the two-dimensional turbulent boundary layer, and for fully developed flow in a circular tube or a flat duct, and attempt to draw some conclusions as to where matters presently stand

W. M. Kays

Papers

Turbulent Prandtl number : where are we ?

Heat transfer in annular passages—hydrodynamically developed turbulent flow with arbitrarily prescribed heat flux

Heat transfer in annular passages. simultaneous development of velocity and temperature fields in laminar flow

Heat transfer to a turbulent boundary layer with varying free-stream velocity and varying surface temperature—an experimental study

The turbulent boundary layer on a porous plate: Experimental skin friction with variable injection and suction