Coupled CFD-DEM modelling to predict how EPS affects bacterial biofilm
deformation, recovery and detachment under flow conditions
Abstract
The deformation and detachment of bacterial biofilm are related to the
structural and mechanical properties of the biofilm itself.
Extracellular polymeric substances (EPS) play an important role on
keeping the mechanical stability of biofilms. The understanding of
biofilm mechanics and detachment can help to reveal biofilm survival
mechanisms under fluid shear and provide insight about what flows might
be needed to remove biofilm in a cleaning cycle or for a ship to remove
biofilms. However, how the EPS may affect biofilm mechanics and its
deformation in flow conditions remains elusive. To address this, a
coupled computational fluid dynamic – discrete element method (CFD-DEM)
model was developed. The mechanisms of biofilm detachment, such as
erosion and sloughing have been revealed by imposing hydrodynamic fluid
flow at different velocities and loading rates. The model, which also
allows adjustment of the proportion of different functional group of
microorganisms in the biofilm, enables the study of the contribution of
EPS towards biofilm resistance to fluid shear stress. Furthermore, the
stress-strain curves during biofilm deformation have been captured by
loading and unloading fluid shear stress to study the viscoelastic
properties of the biofilm.