Fluid Rheological Effects on the Flow of Polymer Solutions in a Contraction–Expansion Microchannel

Micromachines

JoshuaB. Bostwick¹  Xingchen Shao¹  Xiangchun Xuan¹  PurvaP. Jagdale¹  Di Li¹ 

[1] Department of Mechanical Engineering, Clemson University, Clemson, SC 29634-0921 USA;

关键词: non-newtonian fluid;    elasticity;    shear thinning;    inertia;    microfluidics;   

DOI  :  10.3390/mi11030278

来源: DOAJ

【 摘 要 】

A fundamental understanding of the flow of polymer solutions through the pore spaces of porous media is relevant and significant to enhanced oil recovery and groundwater remediation. We present in this work an experimental study of the fluid rheological effects on non-Newtonian flows in a simple laboratory model of the real-world pores—a rectangular sudden contraction−expansion microchannel. We test four different polymer solutions with varying rheological properties, including xanthan gum (XG), polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), and polyacrylamide (PAA). We compare their flows against that of pure water at the Reynolds ( $Re$ ) and Weissenburg ( $Wi$ ) numbers that each span several orders of magnitude. We use particle streakline imaging to visualize the flow at the contraction−expansion region for a comprehensive investigation of both the sole and the combined effects of fluid shear thinning, elasticity and inertia. The observed flow regimes and vortex development in each of the tested fluids are summarized in the dimensionless $Wi-Re$ and ${\chi }_L-Re$ parameter spaces, respectively, where ${\chi }_L$ is the normalized vortex length. We find that fluid inertia draws symmetric vortices downstream at the expansion part of the microchannel. Fluid shear thinning causes symmetric vortices upstream at the contraction part. The effect of fluid elasticity is, however, complicated to analyze because of perhaps the strong impact of polymer chemistry such as rigidity and length. Interestingly, we find that the downstream vortices in the flow of Newtonian water, shear-thinning XG and elastic PVP solutions collapse into one curve in the ${\chi }_L-Re$ space.

【 授权许可】

Unknown