77th Annual Meeting of the APS Division of Fluid Dynamics (November 24, 2024 — November 26, 2024)

P2652209: Viscoelastic Vortex Street

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Authors

• Umang N. Patel, University of Massachusetts Amherst
• Jonathan P. Rothstein, University of Massachusetts Amherst
• Yahya Modarres-Sadeghi, University of Massachusetts Amherst

DOI: https://doi.org/10.1103/APS.DFD.2024.GFM.P2652209

CFD simulations are performed to study the vortex-induced vibrations (VIV) of a cylinder in the inertial-elastic flow at a Reynolds number of Re = 100 and for a range of Weissenberg numbers of 0 < Wi < 10. In this range of Reynolds and Weissenberg numbers, both inertia and elasticity of the flow must be considered when it interacts with a flexibly-mounted cylinder. The FENE-P model is used to describe the viscoelastic fluid. In the wake of the cylinder undergoing VIV in the inertial-elastic flow regime, we observe (i) the primary vortices that are shed from the sides of the cylinder, similar to those observed in the Newtonian fluids, and (ii) the secondary vortices that are shed in between the primary vortices and are caused solely by the viscoelasticity of the fluid. The secondary vortices grow stronger and extend up to a longer distance in the wake with increasing Weissenberg number. For increased elasticity in the fluid, significant polymer deformation is observed in the upstream stagnation region resulting in a region of large elastic stress that acts as a wall around the cylinder. As a result, the stagnation point moves nearly a quarter of the radius upstream of the cylinder creating a finite gap between the shear layers and the cylinder surface. The region of flow separation is both widened and extended further downstream.