Large-scale Lattice-Boltzmann simulations of tracer diffusion in colloidal suspensions out of equilibrium

The main purpose of this project is to use numerical computer simulations to investigate various phenomena that arise in "active matter", meaning systems in which a number of active "agents" consume energy in order to move and exert forces on the medium. As such systems are inherently out of equilibrium, they are expected to have properties not seen in traditional materials, like so-called "bacterial turbulence". Particular focus will be put on the diffusion of passive tracer particles in such systems.

The main approach will be to utilize a Lattice-Boltzmann method to simulate active matter at relatively large scales (containing hundreds of thousands of particles). This allows for the study of long-range hydrodynamic interactions, which are highly relevant for example for bacterial turbulence. Of particular interest is how these phenomena affect the diffusion of tracer particles, and how they are affected by external perturbations, such as concentration gradients and flow fields.

Previously developed FORTRAN-code will be utilized to perform the simulations. Extensions and improvements to the code will be carried out to include perturbations as described above, as well as for example the effect of gravity.