Analysis of viscoelastic flow past a square cylinder in a channel with sudden contraction

Abstract

The present study examines the effectiveness of the geometric modification in stabilizing the viscoelastic (VE) fluid flow through a planar channel with 5:1 sudden contraction. The geometric modification employed in this study includes a square cylinder positioned in front of the contraction plane. The square cylinder pre-deforms the fluid before entering the contraction region. The cylinder causes elongational flow in the wake region as well as shear and elongational flow between the channel and cylinder walls, significantly changing the nature of the flow. We used the open-source software OpenFoam, which is based on the finite volume method, to solve the mass, momentum, and rheological stress-constitutive equations. The Oldroyd-B model mimics the rheological characteristics of the VE fluid. Our research demonstrates that the pre-deformation of VE fluid stabilizes flow in the Wi range of 0–4. Additionally, the salient corner vortex size in the Wi range of 6–10 is effectively reduced by the square cylinder with a blockage ratio of 0.30. Furthermore, the Pakdel–Mckinley stability criterion demonstrates that an increase in Wi beyond the critical value initiates elastic turbulence in the flow.