Microfluidic systems for the analysis of viscoelastic fluid flow phenomena in porous media

Abstract

The Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. RESEARCH PAPERMicrofluidic systems for the analysis of viscoelastic fluid flow phenomena in porous media Abstract In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application.

Extra dissipation and flow uniformization due to elastic instabilities of shear-thinning polymer solutions in model porous media

“…25) as related to extensional flows as the fluid flows through contractions. 26 However, more recent experimental results 27 in model geometries indicate that the succession of converging/diverging flows has little effect on the pressure gradient as compared to the curvature of the streamlines which promote unsteady flows. Generally speaking, the general description of flow of viscoelastic liquids in porous media remains an open issue (see, for example, Ref.…”

“…However, for the relatively small contractions in the studied micromodel (the relative standard deviation of channel width is 0.33), studies have shown that the corresponding extra pressure remain weak. 26,27 It is interesting to discuss the value of Wi c . Elastic instabilities are known to occur in curvilinear flow above a threshold given by a criterion proposed by McKinley et al, 11 with Wi ffiffiffiffiffiffiffiffiffiffi w=R p > M, where R is the radius of curvature of the streamlines.…”

Viscoelastic flow simulations through an array of cylinders

“…For these liquids pressure versus flow rate experiments have been conducted, not only in porous media and packed beds, but also in artificially made geometries that mimic the conditions in a porous medium [1][2][3][4]. From these studies, the following picture has emerged.…”

Assessing the Dynamic Performance of Microbots in Complex Fluid Flows

“…As it was mentioned previously, at the micro-scales (typical scales from the human circulatory system), the elastic effects are enhanced even at low Reynolds numbers [7,54,55]. The complex rheological behaviour of whole blood has been studied and continues to be investigated using new technological advances [56,57].…”