Impact of Motile Bacterial Suspensions on Viscous Fingering and Mixing
Abstract
Viscous fingering is a hydrodynamic instability that occurs when a less viscous fluid displaces a more viscous one. Instead of progressing as a uniform front, the less viscous fluid forms fingers to create complex patterns. Understanding how these patterns and their associated gradients evolve over time is of critical importance in characterizing the mixing of two fluids, which in turn is important to applications such as enhanced oil recovery, bioremediation, and microfluidics. The combinations of fluids that lead to viscous fingering vary, and this work investigates the impact of replacing the less viscous fluid with an active suspension of bacteria. In this series of experiments, a suspension of motile Bacillus subtilis capable of reducing the viscosity of their surrounding fluid via swimming is injected into a Hele-Shaw cell under viscous fingering conditions. Through imaging we obtain high-resolution concentration fields to determine the mixing zone (presence of concentration gradients), which can be characterized by its length and its thickness. The dynamics of interface length and thickness of the mixing zone in these patterns are measured and compared to those of passive fluids (previous work), and we present here the impact these active suspensions have on the formation of viscous fingering patterns as well as the mixing efficiency between the two fluids.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.H51D1499C
- Keywords:
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- 1009 Geochemical modeling;
- GEOCHEMISTRYDE: 1832 Groundwater transport;
- HYDROLOGYDE: 1869 Stochastic hydrology;
- HYDROLOGY