I have been working on and just officially released BondGraphs.jl, a Julia implementation of the bond graph framework. Bond graphs are an energy-based modelling framework that describe energy flow through a physical system, and are especially useful for modelling multi-scale or multi-physical systems.
I’ve tried to make BondGraphs.jl integrate with the wider Julia modelling ecosystem, including ModelingToolkit.jl and Catalyst.jl. The package is still in its early stages and undergoing a lot of development, so feedback is greatly appreciated.