  Flow networks are essential for both living organisms and enginneered
systems. These networks often present complex dynamics controlled, at least in
part, by their topology. Previous works have shown that topologically complex
networks interconnecting explicitly oscillatory or excitable elements can
display rich emerging dynamics. Here we present a model for complex flow
networks with non-linear conductance that allows for internal
accumulation/depletion of volume, without any inherent oscillatory or excitable
behavior at the nodes. In the absence of any time dependence in the pressure
input and output we observe emerging dynamics in the form of self-sustained
waves, which travel through the system. The frequency of these waves depends
strongly on the network architecture and it can be explained with a topological
metric.
