Showing papers by "Giovanni Seminara published in 1979"
TL;DR: In this article, the influence of the asymmetry of the perturbations on the instability of viscous incompressible flow originated by a circular cylinder performing harmonic oscillations around its axis is investigated in the linear regime.
Abstract: The influence of the asymmetry of the perturbations on the instability of viscous incompressible flow originated by a circular cylinder performing harmonic oscillations around its axis is investigated in the linear regime. The critical values of the Taylor number (based on the amplitude of the cylinder tangential velocity and on the thickness of the basic flow) and of the axial wavenumber are found to increase monotonically as the asymmetry parameter (azimuthal wavenumber) increases. This result agrees with previous experimental observations of the author.
7 citations
TL;DR: In this paper, the inviscid centrifugal instability of slowly varying flows is shown to be associated with the lowest-order spatial dependence of the basic flow satisfying Rayleigh's criterion.
Abstract: The inviscid centrifugal instability of slowly varying flows is shown to be asymptotically associated with the lowest-order spatial dependence of the basic flow satisfying Rayleigh's criterion. This result requires special attention for basic flows which reverse their direction. At the instant of reversal the growth rate of the disturbance bifurcates and the choice of the proper branch requires that viscous effects be taken into account within a conveniently small neighbourhood of the branch point. Previous results by Rosenblat (1968) are shown to be incorrect. Such results were based on overlooking the need for viscous effects to be accounted for within a neighbourhood of the bifurcation point. This led to a wrong choice of the path to be followed at bifurcation.