Simulating the biofilm-induced evolution of pore-scale flow in porous media

Abstract:

We present results on the influence of biofilms on hydraulic conductivity. In this
work, we use computational methods to compute the hydraulic conductivity on
biofilms of Shewanella onedensis grown in bead packs. The biofilm and beads were
imaged using X-ray computed microtomography, and the change in hydraulic con-
ductivity was measured from the change in pressure drop across the column during
flow. Our numerical analysis is based on fully-resolved immersed boundary direct
numerical simulations of pre- and post-growth flow fields for three experiments in
polydisperse sphere packings with Re = 0.1, 1, and 10. Correpondence between
the experiments and the simulations is established by matching the effective hy-
draulic conductivity of the columns that is calculated via (1) simulations using
the pore geometries that are derived directly from the micro-CT images, and (2)
differential pressure transducer measurments. We discuss several aspects of how
the simulations are set up, including the representation of the biofilm surface and
interfacial boundary conditions, and study the structural changes to the flow field
as a result of biofilm growth. We also use these numerical data to further validate
the method of volume averaging with closure as a viable tool for predicting the
hydraulic conductivity from knowledge of the pore space geometry.