In this talk we consider two large groups of interacting agents, whose dynamics are influenced by the overall perceived density. Such dynamics can be used to describe two pedestrian groups, walking in opposite directions. Or to model the relocation behavior of two distinct populations, which have a preference to stay within their own group.
We discuss the mathematical modeling in different applications as well as the corresponding PDE models. Furthermore we analyze the long term behavior of solutions and show that already minimal interactions can lead to segregation. Finally we confirm our analytical results and illustrate the rich dynamics with numerical experiments.