Bondgraphs and practical simulation

This is the introduction to our Bondgraph (BG) issue, which deals with several problems of practical simulation. First we define the art of Bondgraphing, where causality is stressed. One chapter makes a comparison of traditional versus BG modeling. Then follows some help with practical simulation, the paracheck and compact physical units. Next there is estimation of time constants and resonance frequencies, which determine the required time step in the simulation. Finally, a trap is shown with quadratic resistances, which really comes from faulty physical reasoning. We conclude with the advantages and limitations of BG and with some suitable computer programs.