Numerical investigation of viscoelastic flow characteristics: Giesekus fluid past a circular cylinder near a flat wall

This study numerically investigates viscoelastic flow dynamics around a cylinder near a flat wall using the Giesekus model in OpenFOAM. For the boundary layer on the flat wall, both elastic and shear-thinning properties reduce boundary layer thickness. The coupled elastic and shear-thinning effects of the Giesekus fluid flow around the near-walled cylinders are analyzed through systematic parameters. At high mobility factor, increasing the Weissenberg number primarily enhances the shear-thinning effect, leading to intensified drag and lift fluctuations. However, at low mobility factor, it mainly strengthens the elastic effect, evidenced by the elongation of recirculation zone in the wake. The comparative simulations using the Carcarau model further reveal the competing flow mechanisms between flow stabilization due to elasticity and destabilization caused by shear thinning. In addition to the fluid property parameters, smaller gap ratios enhance flow stability by maintaining lower flow velocity in the gap. Conversely, larger gap ratios increase the velocity, causing high-momentum fluid flow through the gap to deflect and interact with the shear layer formed by the cylinder’s upper wake, thereby triggering vortex shedding. Similarly, a reduced flow development length accelerates the flow velocity in the gap and thins the boundary layer of the plat wall, which promotes flow instability. Both larger gap ratios and shorter development lengths increase the drag and alter the lift direction.