School of Civil and Environmental Engineering
Ph.D. Thesis Defense Announcement
Multiphase Flow with Active Suspensions of Motile Bacteria in Porous Media
Dr. Sheng Dai (CEE)
Dr. J. David Frost (CEE); Dr. Haiying Huang (CEE); Dr. Leon A. Van Paassen (ASU); Dr. Peter Yunker (PHYS)
Date and Time: Friday, June 3, 2022 at 10 am
Location: SEB 122 or Online
Multiphase flow in porous media has been integral in many industrial and environmental applications, such as geological carbon sequestration, enhanced oil and gas recovery, and the transport of nutrients or contaminants in soils. These flow processes are mainly governed by flow conditions, fluid rheology, interfacial properties, wettability, and pore structure. The presence of active particles like motile bacteria in suspension liquids can significantly alter the fluid rheology and interfacial properties, and thus, change the dynamic behavior and fluid displacement patterns in porous media. This research investigates immiscible fluid flow of motile bacterial suspensions in porous media, with a focus on understanding the role of various bacterial motions in changing fluid rheology, dynamic contact angle, and the drainage and imbibition efficiency in microfluidics. Three Escherichia coli (E. coli) strains – ATCC9637 (motile), HCB136 (paralyzed flagella), and HCB137 (deflagellated) – were deployed in this study. The results show that bacterial suspensions exhibited non-monotonic viscosity changes with shear rates. In particular, at a low shear rate regime, ATCC9637 and HCB137 reduced the suspension viscosity due to their motility; while the HCB136 suspension, as other passive suspensions, exhibited increased viscosity with increasing cell concentrations due to the interactions of among paralyzed flagellated E. coli. The presence of E. coli increased both advancing and receding contact angles, and reduced the contact angle hysteresis, mainly by enhanced pinning effect. Motile E.coli particles altered the drying process in microfluidic chips more evidently than in the wetting process, possibly due to the lower Peclet number of the flow during drying. As the concentration of ATCC9637 particles increased, the drying displacement patterns shifted from capillary fingering to stable displacement. In summary, suspensions of motile bacteria exhibited a unique rheological behavior due to their active interactions with surrounding fluids and thus altered the flow processes in porous media. The research findings shed light on using suspensions of (synthetic) active particles for adaptive control of flow in porous media.