Parametric Study of Viscoelastic Flow Simulations in Microfluidic Devices

Abstract

The open-source C++ toolbox OpenFOAM is used to perform the Computational Fluid Dynamics (CFD) simulations in two-dimensional microfluidic devices to characterize the viscoelastic flow. The Oldroyd-B constitutive equation is coupled with continuity and momentum equations. Multiple stabilization methods are applied to the numerical simulation to simulate High Weissenberg Number Problem (HWNP) in the microchannel. We applied the Log Conformation Reformulation (LCR) method to guarantee the positive definiteness of the stress tensor. The CUBISTA scheme and the improved Both Side Diffusion (iBSD) method are applied to predict the flow behavior at high elasticity regions without numerical oscillations. Various microstructures, including circles and flat plates, are placed in the center of the channel as the confinement. Our previous work demonstrated that the polyhedral mesh with hexahedral inflation layers effectively meshes complex microstructures in microchannels. A viscoelastic fluid is injected from the inlet at varying flow rates, corresponding to the local Weissenberg number up to 25. A parametric study is conducted on the first normal stress difference (N1) in specific regions with an accurate prediction of the viscoelastic flow field near the microstructures.