Event

Complex life larger than a humble nematode would not be possible without a circulatory system. Plants, fungi, and animals have developed vascular systems of striking complexity to solve problems of long distance nutrient delivery, waste removal, and information exchange. These disparate vascular systems are constrained by the same physics and their structure is governed by the common universal principles such as a hierarchy in the vessel diameters and the existence of multiple loops. Biological flow systems are also frequently not static, but dynamically alter the diameters of their vessels in order to optimize their intended function, e.g. deliver the flow with as little dissipation as possible, while being resilient to damage [1-3].   The relationship between flow and pressure drop in vessels is frequently treated as analogous to Ohm’s law, i.e. linear, but it does not have to be. We present some new work on how a system of vessels can spontaneously produce and sustain dynamic oscillations due to a nonlinear flow-pressure drop relationship. We show how vessels propagate pressure pulses, how they redirect large volumes of fluid to different locations of the network, and how introducing defects in the network can modify the dynamics. Last, we discuss how we can modify the connectivity of the network to control flow in unexpected ways, and what this dynamic flow network behavior can tell us about blood flow oscillations in the brain and living systems in general.

[1] H. Ronellenfitsch and E. Katifori, “Global optimization, local adaptation and the role of growth in distribution networks”, Phys Rev Lett 117, 138301 (2016)

[2] T. Gavrilchenko and E. Katifori, “Resilience in hierarchical fluid flow networks", Phys Rev E 99, 012321 (2019)

[3] H. Ronellenfitsch and E. Katifori, “Phenotypes of Fluctuating Flow: Development of Distribution Networks in Biology and Trade-offs between Efficiency, Cost, and Resilience”, arXiv:1707.03074 (submitted)