Do you have a problem with a know solution that isn't solving properly?
One thing about flow is that the developers have spent a lot of time to ensure the interface makes it easy to setup the problems and output good, accurate results . They've also documented much of it but sometimes it isn't exactly obvious to non developers on the reason why they used a certain solving method. Concentrating on the solutions to start may help yoga newer your question. Or dig into the References of the references.