Collective behavior of particles in fluids

Paris, December 14-17, 2020

**Christiane Helzel
** (Universität Düsseldorf)

*Modelling and Simulation of Sedimentation in Suspensions of Rod-Like Particles*

The starting point of our considerations is a coupled system consisting of a kinetic equation which is coupled to a macroscopic flow equation (Stokes or Navier-Stokes) and which describes the motion of a suspension of rigid rod-like particles under the influence of gravity. A reciprocal coupling leads to the formations of clusters: The buoyancy force creates a macroscopic velocity gradient that causes the microscopic particles to align so that their sedimentation reinforces the formation of clusters of higher particle density.

Since the coupled system is high-dimensional (five spatial dimensions + time), we are interested in the derivation of simpler systems which describe the dynamics observed in experimental studies without resolving all the details of the full system. We will discuss several approaches for the derivation of simplified systems and present numerical simulations which illustrate that these simplified models can reproduce the formations of clusters.

This is joint work with Athanasios E. Tzavaras (KAUST).

See slides and record.