Purely elastic linear instabilities in parallel shear flows with free-slip boundary conditions

Martin Lellep*, Moritz Linkmann, Bruno Eckhardt, Alexander Morozov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We perform a linear stability analysis of viscoelastic plane Couette and plane Poiseuille flows with free-slip boundary conditions. The fluid is described by the Oldroyd-B constitutive model, and the flows are driven by a suitable body force. We find that both types of flow become linearly unstable, and we characterise the spatial structure of the unstable modes. By performing a boundary condition homotopy from the free-slip to no-slip boundaries, we demonstrate that the unstable modes are directly related to the least stable modes of the no-slip problem, destabilised under the free-slip situation. We discuss how our observations can be used to study recently discovered purely elastic turbulence in parallel shear flows.
Original languageEnglish
Article number928
Pages (from-to)1-11
Number of pages11
JournalJournal of Fluid Mechanics
Volume928
Issue numberR3
Early online date12 Oct 2021
DOIs
Publication statusPublished - 10 Dec 2021

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