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Title:On stability of shear flows with combined temporal and spatial imperfections
Author(s):Riahi, Daniel N.
Subject(s):Shear Flows
Temporal & Spatial Imperfections
Abstract:This paper investigates stability of secondary shear flows for cases where the upper boundary of the shear layer has imperfections with respect to time and space. Such imperfections could arise, for example, by general time dependent environmental disturbances as in the cases of boundary layer or free shear flows in practical applications. A general theory is developed which deals with the most critical disturbances, of either discrete or spectral origin, near the onset of the primary instability of the shear flows. Certain types of the boundary imperfections are found to lead to the preference of single or multi-modal forms of the secondary flows with multiple scales. Time dependent imperfections are found to lead to weakly time dependent secondary flows for the cases where the most critical disturbances are stationary. The stable secondary flows, resulted from discrete modal disturbances, are found to exhibit periodic or quasi-periodic structures in time or in space for the cases where the most critical disturbances are non-stationary. The stable secondary flows, resulted from non-stationary disturbances with continuous spectrum of modes, are found to exhibit quite unusual and non-regular structures, under certain forms of the boundary imperfections. In particular, the preferred flow structure can be non-periodic in time or in space.
Issue Date:1996-10
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 835
Genre:Technical Report
Rights Information:Copyright 1996 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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