suppressMessages(library(GA))
library(data.tree)

dynVisc = 0.0000181 
density = 1.225 
roughness = 0.01

tree <- CreateRegularTree(4, 2)
tree$Set(flowRate = 0.1, filterFun = isLeaf)
tree$Do(function(x) x$flowRate <- Aggregate(x, "flowRate", sum))

bitnum=7
nvars=tree$totalCount