Efficient Calculation of Transient Flow in Simple Pipe Networks

Extensions to the conventional method of characteristics allow transient conditions in simple pipe networks to be efficiently calculated. In particular, treating both boundary conditions and network topology in a general and comprehensive fashion simplifies the solution of many combinations of hydraulic devices. The algebraic framework presented includes a flexible integration of the friction loss term that reduces to previous linear approximations as special cases. In addition, an explicit algorithm is derived for a general hydraulic element called an external energy dissipator. This boundary condition conveniently represents surge tanks, relief valves, storage reservoirs, valves discharging to the atmosphere, and many other common devices. Significantly, the solution remains explicit even if friction losses and inertia effects are present in both the storage element and a connecting pipe. This comprehensive approach to transient analysis simplifies control logic, encourages accurate reporting of field data, and improves execution times. The procedure is illustrated by analyzing transient conditions in a small network containing a variety of devices.