Computational fluid dynamics as a tool to understand the motility of microorganisms

In this work we demonstrate the utility of a new computational algorithm, based on the finite volume method, for simulating the motility of microorganisms. The approach is adopted from our work on discrete particle modeling. The shape of a swimming cell is reconstructed as a contiguous sequence of spherical particles at discrete locations on the surface of the cell head and flagella, and the motion of each sphere is prescribed from experimentally observed motions. The spherical particles contribute to the fluid's momentum as point forces. By computing the hydrodynamic interaction of the prescribed motion, we can calculate a propulsive velocity. We extensively validate our model with analytical results and other established numerical methods. Both qualitative and quantitative agreement are demonstrated across a wide range of low Reynolds number phenomena. Since it is implemented as an add-on module to computational fluid dynamics solvers such as FLUENT or OpenFOAM, it has the potential for broad utility in the viscous regime.