Скачать или смотреть AGU24 - H33K-1074 - Tracer Simulation of a Bioclogged Sandy Medium after 15 hours of biofilm growth

550 seconds of CFD simulation showing the movement of a passive tracer in a bioclogged domain with a biofilm permeability of 7E-9 m². The simulation runs at 20 frames per second, providing detailed visualization of the tracer dynamics.
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Authors:
Veronica Morales
Jorge Vargas Lara
Felipe Carreño-López
Eleanor Fadely
Jasquelin Pena
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Microorganisms form organized biofilms in both natural and engineered porous media, offering advantages in applications such as groundwater pollution barriers. The biofilm life cycle follows stages of initial cell attachment, formation, maturation, and dispersal. Throughout this cycle, biofilms interact with their physical environment, influencing hydrological properties of porous media. At the Darcy-scale, biofilms induce consistent permeability reductions of the entire porous domain. At the pore-scale, the structural changes resulting from biofilm development are much more nuanced and poorly understood. Traditionally, biofilms have been modeled as impermeable domains within porous media, which poses problems for investigating chemical transformations that occur within biofilms. Resolving this limitation in current reactive transport models requires in situ measurements of biofilm permeability alongside new computational models that capture the dynamic properties of biofilms. The aim of this work is thus twofold. First, we investigate how the biofilm permeability changes as biofilms grow within a porous medium. Second, we study how flow arrangement and solute mixing evolve as the system becomes progressively bioclogged. Our study leverages highly resolved two-dimensional optical microscopy time-lapse images of bacterial biofilms in a microfluidic reactor patterned after a sandy soil and a Computational Fluid Dynamics model to numerically solve the pore-scale fluid flow (solving the incompressible Navier-Stokes equations) and solute transport (employing a passive scalar transport equation). The average biofilm permeability is ascertained from the flow data and experimentally determined values of discharge and pressure gradient. Mixing effects, preferential paths, and residence time distributions are determined from scalar dissipation rates, percolation threshold, and solute breakthrough curves, respectively. This study sheds light on the importance of biofilm permeability and pore-scale hydrodynamics in controlling the efficiency of biologically driven reactions requiring reactant biofilm uptake.