Numerical simulations of viscoelastic flow over a confined cylinder in microchannels

In this study, several 2D numerical simulations on a non-Newtonian flow over a confined cylinder placed in a rectangular microchannel are carried out at different Weissenberg (Wi) numbers. In particular, the Oldroyd-B model implemented in open source code OpenFOAM is employed to capture the three basic ingredients of polymer rheology, viz., anisotropy, elasticity and relaxation. Numerical calculations indicate that the flow structure particularly in the downstream is influenced by the presence of the cylinder. As Wi or the channel height increases, the velocity-recovery length required increases. It is observed that both the pressure drop across the channel and the elastic stress magnitude in the downstream grow exponentially with Wi. However it is interesting to observe that recirculation zones appear at Wi = 1.2 with a modest increase in pressure drop compared to Newtonian flow.