Mesoscale particle-based simulations of flow in expansion-contraction microchannels at low Reynolds number

Abstract

Polymer flooding is an enhanced oil recovery technique that enables the extraction of significantly more oil than conventional methods. The good performance of polymer flooding is believed to stem from a phenomenon known as elastic turbulence, a hydrodynamic instability that can occur for low Reynolds number flows through expansion-contraction microchannels. Experiments have shown that oil recovery efficiency is influenced by the polymer’s architecture and hydrophobic associations. However, it remains unclear whether these changes are linked to elastic turbulence because little is known about how a polymer's molecular structure impacts this phenomenon. Mesoscale particle-based simulations are a promising approach to address this knowledge gap; however, they have not yet been applied to elastic turbulence. As a first step toward doing so, we have simulated the low-Reynolds-number flow of a Newtonian fluid through an expansion-contraction microchannel. The validity of the simulations was assessed using a theoretical solution derived using a regular perturbation method. The simulations were in good agreement with theory for microchannel geometries in which the theory was expected to be accurate, but the simulations also enabled us to simulate flows for which the theory was not accurate. This work establishes a baseline against which simulations with different polymers can be compared to characterize the presence of elastic turbulence.