Abstract

MOSS, E.A.  and  DA SILVA, D.F.. The use of an integral base flow solver to establish the stability of spatially developed pipe flows impulsively started from rest. R&D j. (Matieland, Online) [online]. 1995, vol.11, pp.68-72. ISSN 2309-8988.

This work investigates the stability of a spatially developed pipe flow impulsively started from rest. The laminar base flow was established using an integral method and eigenvalues of the Sexl stability equation were obtained using a finite difference approach in conjunction with the Q-Z algorithm. A strong qualitative correlation was obtained between the present data and those for a steady pipe entrance flow. Utilisation of a dimensionless shear stress parameter to plot these results in a common framework results in the inference that the velocity profiles and hence stability characteristics of the two flow systems become coincidental only towards the Hagen-Poiseuille limit. It it shown that, beyond a well-defined dimensionless time in the process, the flow becomes unconditionally stable to small disturbances. Unlike the situation for steady pipe entrance flows, measurements taken in a temporally developing flow at a spatially developed downstream station may for a period of time be isolated from the effects of upstream-generated finite amplitude disturbances. It was concluded that such flows potentially provide a means of experimentally resolving the contentious pipe flow stability problem.

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