LVTrans is an open source transient simulation program for hydraulic piping systems. It is particularly useful for transient simulation of hydro power plants with Francis or Pelton turbines.
LVTrans is entirely programmed in LabVIEW with the graphical programming language called "G". The reference for the theory behind LVTrans is mainly the book Fluid Transients in Systems by Wylie and Streeter or a similar text book, along with decades of experience in simulations and field work on hydro power plants.
The "Base" or the free community edition of LabVIEW is a requirement.
A blog about transient simulations can be found here. This is updated from time to time.