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Simulate transient hydraulics

Initial steady-state:

Users select one (steady-state) time-step from an existing real-time hydraulic simulation, as the starting conditions for the user's specified transient event (e.g. power failure).


A transient hydraulic simulation covers a user-defined duration.  An acceptable duration is limited by:

  • the time taken for the system to reach the stable conditions, representing the target steady-state; and
  • the amount of free disk space available on the computer.

Long transient simulations at sub-second calculation intervals, can rapidly create output files that are many gigabytes in size.

During a transient simulation:

The Method of Characteristics computes the response as the system transitions from the prevailing steady-state to a new steady-state;

  • time steps forward at a user-defined interval, which can be a small as one 100,000th of a second;
  • demand from junctions on the system vary with the available pressure; 
  • autonomous, in-line devices such as pressure reducing valves, operate to match current hydraulic conditions;
  • in-line valves and pumps operate to match user-defined, time-based changes in valve position or pump speed;
  • surge-protection devices (such as air valves, surge tanks, pressure vessels) operate to match current hydraulic conditions;
  • result reports are created at user-defined intervals (e.g. 5 seconds), with changes in device state reported in-between;
  • maximum and minimum values for all locations and devices are records at every time step; and
  • performance parameters for all components are graphed at a user-defined frequency (i.e. each Nth time step). This filtering improves on-screen display performance.