A finite element approach for the coupled numerical simulation of fluid-structure interaction and mass transfer of moving biofilm structures

Biofilms are communities of microorganisms surrounded by an extracellular selfsecreted polymer matrix. Their formation is desirable in some applications, while being completely penalizing in other cases. Nonetheless their mechanics, architecture and interaction with surrounding fluid are still not well understood and a proper modelling becomes crucial in the process of understanding their macro-scale dynamic and the way they interact with the environment. To date however only limited attempts have been done in order to model the substrate transport and the biofilm transient interaction with the surrounding fluid. In this work, we propose a finite element approach, developed in our in-house research code BACI, for the coupled numerical simulation of fluid-structure interaction and mass transfer of moving biofilm structures. Biofilm interaction with the surrounding fluid is modelled through an Arbitrary Lagrangian-Eulerian (ALE) approach, while the mass transfer is calculated through the solution of the dynamic convection-diffusion-reaction equation. The equations governing the fluid flow and the structure displacement are solved monolithically, while the mass transport equation is solved subsequently using the calculated flow field and assuming a non-linear Monod kinetic. Among the several shapes a biofilm can form, that one consisting of a base attached to the substratum and a tail free to move in the flow is selected. In nature however streamers are not usually isolated and, in this work, not only a single streamer is studied, but also the relative influence of the oscillations of multiple streamers, demonstrating how different biofilm streamers interact with the fluid and with each other.     «

Biofilms are communities of microorganisms surrounded by an extracellular selfsecreted polymer matrix. Their formation is desirable in some applications, while being completely penalizing in other cases. Nonetheless their mechanics, architecture and interaction with surrounding fluid are still not well understood and a proper modelling becomes crucial in the process of understanding their macro-scale dynamic and the way they interact with the environment. To date however only limited attempts ha...     »