Problem

What is an Extended Period Simulation (EPS) and how can I run it?

Solution

When the variation of the system attributes over time is important, an extended period simulation is appropriate. This type of analysis allows you to model tanks filling and draining, demands/loads changing over time (via assigned patterns), regulating valves opening and closing, and pressures and flow rates changing throughout the system in response to varying load conditions and automatic control strategies.

While a Steady State simulation may tell whether the system has the capability to route calculated loads, an extended period simulation indicates whether the system has the ability to provide acceptable levels of service over a period of minutes, hours, or days.

Data requirements for extended period simulations are greater than for steady state runs. In addition to the information required by a steady state model, you also need to determine and assign patterns to demands/loads and set operational rules for pumps and valves (Components > Controls.)

How to Run an Extended Period Simulation

Go to Analysis > Calculation Options. Under the Steady State/EPS Solver, double click on the active calculation option to open the Properties Grid.

Under the section Calculation Times, find Time Analysis Type. This can be set to Steady State or EPS.

After computing, you can right click on elements and choose "Graph" to see time series results. You can also use the Time Browser (Analysis > Times) to advance forward in time, which will update results in places such as the property grid, Flextables and plan view annotations and color coding.

Note that analysis types like Trace, Age, and Constituent are always EPS runs. The Fire Flow analysis type is strictly a stead state run.

See Also

Difference between EPS and transient simulation