Floquet stability analysis of viscoelastic flow over a cylinder

David Richter, Eric S.G. Shaqfeh, Gianluca Iaccarino

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

A Floquet linear stability analysis has been performed on a viscoelastic cylinder wake. The FENE-P model is used to represent the non-Newtonian fluid, and the analysis is done using a modified version of an existing nonlinear code to compute the linearized initial value problem governing the growth of small perturbations in the wake. By measuring instability growth rates over a wide range of disturbance spanwise wavenumbers α, the effects of viscoelasticity were identified and compared directly to Newtonian results.At a Reynolds number of 300, two unstable bands exist over the range 0. ≤ α≤ 10 for Newtonian flow. For the low α band, associated with the "mode A" wake instability, a monotonic reduction in growth rates is found for increasing polymer extensibility L. For the high α band, associated with the "mode B" instability, first a rise, then a significant decrease to a stable state is found for the instability growth rates as L is increased from L= 10 to L= 30. The mechanism behind this stabilization of both mode A and mode B instabilities is due to the change of the base flow, rather than a direct effect of viscoelasticity on the perturbation. © 2011 Elsevier B.V.
Original languageEnglish (US)
Pages (from-to)554-565
Number of pages12
JournalJournal of Non-Newtonian Fluid Mechanics
Volume166
Issue number11
DOIs
StatePublished - Jun 2011
Externally publishedYes

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