  We study the dynamics of interacting agents from two distinct inter-mixed
populations: One population includes active agents that follow a predetermined
velocity field, while the second population contains exclusively passive
agents, i.e. agents that have no preferred direction of motion. The orientation
of their local velocity is affected by repulsive interactions with the
neighboring agents and environment. We present two models that allow for a
qualitative analysis of these mixed systems. We show that the residence times
of this type of systems containing mixed populations is strongly affected by
the interplay between these two populations. After showing our modeling and
simulation results, we conclude with a couple of mathematical aspects
concerning the well-posedness of our models.
