Linear stability analysis of purely elastic travelling-wave solutions in pressure-driven channel flows. (25th March 2023)

• Record Type: Journal Article
• Authors: Lellep, Martin; Linkmann, Moritz; Morozov, Alexander
• Is Part Of: Journal of fluid mechanics. Volume 959(2023)
• Publication Date: 2023-03-25
• Subjects: polymers -- shear-flow instability -- bifurcation; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2023.100
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract: Abstract : Recent studies of pressure-driven flows of dilute polymer solutions in straight channels demonstrated the existence of two-dimensional coherent structures that are disconnected from the laminar state and appear through a subcritical bifurcation from infinity. These travelling-wave solutions were suggested to organise the phase-space dynamics of purely elastic and elasto-inertial chaotic channel flows. Here, we consider a wide range of parameters, covering the purely elastic and elasto-inertial cases, and demonstrate that the two-dimensional travelling-wave solutions are unstable when embedded in sufficiently wide three-dimensional domains. Our work demonstrates that studies of purely elastic and elasto-inertial turbulence in straight channels require three-dimensional simulations, and no reliable conclusions can be drawn from studying strictly two-dimensional channel flows.