  We present a 2D parallel implementation of the modified Cahn-Hilliard
equation for the simulation of a biofilm in an aqueous enviroment. Biofilms are
attached microbial communities made of many different components and can have
both positive and negative effects. They can be used for bioremediation but
also are the cause of the majority of chronic infections. It is for these
reasons that we study them. Due to their composition being mostly water we
choose to model them as an incompressible fluid. We used a visco-elastic phase
separation model based on the modified Cahn-Hilliard equation and the
Flory-Huggins energy density. We present results of a simulation showing
detachment of a biofilm protrusion from a base layer of biofilm due to the flow
over the biofilm. The parallelization was accomplished using PETSc (Portable,
Extensible Toolkit for Scientific Computing), specifically the DMDA abstraction
layer within PETSc. DMDA provides a useful interface for the solution of linear
systems arising from structured grid discretizations. We evaluate the parallel
performance of the implementation with a strong scaling test and calculate the
speedup for various mesh sizes.
