Epanet hydraulic simulation model calculates hydraulic heads at junctions and flow rates via links to a fixed set of reservoir levels, tank levels and water demands over a succession of time points. From one time step to the next, reservoir levels and junction demands are updated according to their prescribed time patterns, while tank levels are updated using the current flow solution. The solution for heads and flows at a given point in time involves simultaneously solving the conservation of the flow equation for each junction and the Head Loss ratio on each link in the network. This process, known as hydraulic balancing of the network, requires the use of an iterative technique to solve the nonlinear equations involved. EPANET employs the Global Gradient Algorithm for this purpose.
The hydraulic time interval used for extended period simulation (EPS) is user definable. A typical value is 1 hour. Shorter than normal time steps will automatically occur whenever one of the following events occurs:
This topic is subdivided into: