Sen, P. K., Veeravalli, S. V., Carpenter, P. W. (Peter William), 1942-, Joshi, G. and Josan, P. S.. (2007) Organised structures in wall turbulence as deduced from stability theory-based methods. Sadhana, Vol.32 (No.1-2). pp. 51-64. ISSN 0256-2499

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Abstract

In earlier work, we have explored the relevance of hydrodynamic stability theory to fully developed turbulent wall flows. Using an extended Orr-Sommerfeld Equation, based on an anisotropic eddy-viscosity model, it was shown that there exists a wide range of unstable wave numbers (wall modes), which mimic some of the key features of turbulent wall flows. Here we present experimental confirmation for the same. There is good qualitative and quantitative agreement between theory and experiment. Once the dominant coherent structure is obtained from stability theory, control of turbulence would be the next logical step. As shown, the use of a compliant wall shows considerable promise. We also present some theoretical work for bypass transition (Klebanoff/Kmodes), wherein the receptivity of a laminar boundary layer to a vortex sheet in the freestream has been studied. Further, it is shown that triadic interaction between K-modes, 2D TS waves and 3D TS waves can lead to rapid algebraic growth. A similar mechanism seems to carry over to inner wall structures in wall turbulence and perhaps this is the "root cause" for sustenance of turbulence.

Item Type:	Journal Article
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Divisions:	Faculty of Science > Engineering
Journal or Publication Title:	Sadhana
Publisher:	Indian Academy of Sciences
ISSN:	0256-2499
Date:	February 2007
Volume:	Vol.32
Number:	No.1-2
Number of Pages:	14
Page Range:	pp. 51-64
Identification Number:	10.1007/s12046-007-0005-y
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Open Access
URI:	http://wrap.warwick.ac.uk/id/eprint/31774

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