Where does all the value end up when every link is one-way? A link turns thick orange, animated toward the node it points to, while its tail holds more value than its head. At the defaults all links go quiet within about 60 ticks as the inner nodes empty.
Try this Choose the Bottleneck preset, which builds a smaller tree (10 of 45 nodes linked). Within about 25 ticks the star's number disappears and the leaves hold all 100 units, in shares such as 50, 16.7 or 4.2. Changing diffusion-rate mid-run (it takes effect live) changes how fast this happens, not the final shares.
About this model Where it ends up
Based on Diffusion on a Directed Network from the NetLogo Models Library. A quantity spreads over one-way links, each node passing a share of what it holds to the nodes it points to, so the total is conserved and where it settles is decided by the direction of the links.
Setup places population nodes, gives node 0 (the amber star) 100 units, links it to one random node, then adds round(population × 3 × link-chance / 100) links with the preferential strategy, which attaches unlinked nodes one at a time as children of well-connected nodes. At the defaults that makes 21 links forming a tree rooted at node 0, every link pointing away from it; the other 33 nodes get no links. Each tick every node sends diffusion-rate percent of its value, split equally, along its outgoing links, and nodes with no outgoing links keep what they get. population and link-chance are read at setup, diffusion-rate every tick.
Because the network is a tree, no value comes back and no node receives from more than one other, so nothing pools at a hub. Each leaf ends with 100 divided by the branching along its path from the source. Only when link-chance is above about 33 are there enough links to attach every node, and only then do links outside the tree appear.
