Fluid flows containing rigid particles appear in many applications. While spherical particles in fluids is a well-studied area, the assumption that particles are spheres is almost never realistic in applications. To discretise this coupled fluid-rigid body problem while being flexible with respect to the geometry of the resulting fluid domain, we use unfitted finite element methods.

The complexity of this problem is very large and dependent on factors such as the size and number of particles, contact between particles resulting in topology changes, as well as interaction between the particles and the surrounding fluid. With a decrease in the size of the particles and an increase of the number of particles, fully resolved direct numerical simulations will become infeasible. It is therefore necessary to develop new methods which reduce the complexity of this problem sufficiently for efficient computability. However, these methods must also deal with contact between particles, as well as the interaction between the particles and the surrounding fluid with sufficient accuracy.