Pressure-gradient-dependent logarithmic laws in sink flow turbulent boundary layers

Dixit, Shivsai Ajit and Ramesh, ON (2008) Pressure-gradient-dependent logarithmic laws in sink flow turbulent boundary layers. In: Journal of Fluid Mechanics, 615 . pp. 445-475.

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Abstract

Experiments were done on sink flow turbulent boundary layers over a wide range of streamwise pressure gradients in order to investigate the effects on the mean velocity profiles. Measurements revealed the existence of non-universal logarithmic laws, in both inner and defect coordinates, even when the mean velocity descriptions departed strongly from the universal logarithmic law (with universal values of the Kármán constant and the inner law intercept). Systematic dependences of slope and intercepts for inner and outer logarithmic laws on the strength of the pressure gradient were observed. A theory based on the method of matched asymptotic expansions was developed in order to explain the experimentally observed variations of log-law constants with the non-dimensional pressure gradient parameter (Δp=(ν/ρU3τ)dp/dx). Towards this end, the system of partial differential equations governing the mean flow was reduced to inner and outer ordinary differential equations in self-preserving form, valid for sink flow conditions. Asymptotic matching of the inner and outer mean velocity expansions, extended to higher orders, clearly revealed the dependence of slope and intercepts on pressure gradient in the logarithmic laws.

Item Type:	Journal Article
Publication:	Journal of Fluid Mechanics
Publisher:	Cambridge University Press
Additional Information:	Copyright of this article belongs to Cambridge University Press.
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	11 Aug 2009 07:41
Last Modified:	19 Sep 2010 04:57
URI:	http://eprints.iisc.ac.in/id/eprint/17479

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