Options dialog - Simulation Defaults page

Continue Simulation after No Solution Snapshot

Determines whether the simulation stops or continues if the engine fails to reach a solution within the maximum number of iterations specified in the Schedule Hydraulic Run view.

If the simulation is to continue, a warning is displayed in the Run Control window. This warning is also listed in the log results for the simulation.

Stop simulation if reservoir empties

Determines whether the simulation stops or continues if a reservoir depth falls below minimum operating level.

If the simulation is to continue, a warning that the reservoir is empty is displayed in the Run Control window. This warning is also listed in the log results for the simulation.

The subsequent behaviour of the simulation will depend on the setting of the Stop outflow from empty reservoirs option. See below for details.

Stop outflow from empty reservoirs

Provides the option to stop outflow from a reservoir when the depth in the reservoir falls below minimum operating level. Will only come into operation if the Stop simulation if reservoir empties option is set to "No".

If the value is set to "No", InfoWorks WS Pro will continue computation assuming that the reservoir water level never falls below the reservoir minimum operating level. The amount of water needed to maintain head at that level is calculated and reported as a "Deficit" result.

If left as default "Yes", outflow from the reservoir will be stopped at the next timestep after the reservoir falls below minimum operating level. Any demand or transfer supplied solely by the empty reservoir will become isolated. The isolated demand/transfer will be cancelled until the reservoir depth rises to above minimum operating level.

IMPORTANT: A transfer node acting as an inflow is treated as a (negative) demand and will be isolated and cancelled.

Enforce Valve/PST regulation tolerance (could increase run-time!)

Provides the option to enforce solving for both the valve regulation precision percentage (specified on the Valve Control page) and the PST regulation tolerance (specified on the Simulation Options dialog) in addition to the Computational Accuracy specified on the Schedule Hydraulic Run view.

If left as default "No", once the flow balance set by the Computational Accuracy has been achieved the timestep is deemed to be solved, regardless of the Valve/PST regulation tolerance setting.

If the value is changed to "Yes" the simulation will continue beyond the computational accuracy solution up to a maximum of 99 iterations.

If, after the maximum number of iterations, a value within a tolerance setting has still not been achieved, you will be informed via the run dialog.

Show imagessages for all isolated nodes with demand

Determines whether the warning messages in the Run Control window and log results display the number of isolated nodes with demand only, or node name and total isolated demand for each isolated node.

PST Variable Speed regulation tolerance as % of target value

The regulation tolerance can be set to any value between 0.5% and 10% of target value specified on the Pump Control Data page.

This tolerance setting will be used if the option to enforce regulation tolerance in the Simulation Options dialog is selected.

Use dynamic friction factors

If "Yes" (default), InfoWorks WS Pro converts the Hazen Williams roughness coefficient C, or the Colebrook-White roughness coefficient k, to the equivalent Darcy-Weisbach factor depending on the Reynolds number for flow in each pipe. The conversion is re-evaluated at each iteration of the simulation.

If "No", InfoWorks WS Pro converts the Hazen Williams coefficient, C, to a Darcy-Weisbach friction coefficient only once for each pipe, assuming a flow speed of 1 m/s.

See Pipe Calculations for further details.

Use modified CW-Moody friction factor

Determines whether to use cubic spline interpolation or constant value method (default) to convert Colebrook-White roughness k, to Darcy-Weisbach friction coefficient l.

See Pipe Calculations for further details.

Use Local Convergence Acceleration

If "Yes", flow errors at individual nodes are also examined. Different factors can be applied at different nodes allowing the solver to reach convergence more quickly.

If "No", the solver examines the network-wide flow errors to determine factors to be applied to the head at nodes for each iteration.

Add scheduled control times

Insert an additional snapshot where a time controlled profile change occurs outside of the hydraulic timestep (specified Timestep on the Schedule Hydraulic Run view).

Use Dynamic TimeSteps

Insert an additional snapshot where a reservoir level controlled profile change occurs before the next scheduled timestep. (Hydraulic Timestep specified on the Schedule Hydraulic Run view or additional timestep scheduled due to Add scheduled control times option.)

Dynamic Control TimeStep

Timestep (mins) at which user programmable controls and regulator (pump or valve) profiles in control data will be checked. The Dynamic Control Timestep must be less than the hydraulic timestep specified on the Schedule Hydraulic Run view for controls to be examined.

If the timestep is left at the default value of 0, the Hydraulic Timestep will be used.

An additional snapshot will be inserted if a change in regulator state (e.g. PST speed), or regulator target value (e.g. target flow), occurs before the next scheduled timestep.

Advise on Hydraulic Transients

Produce additional results to provide a qualitative estimate of areas potentially experiencing high or low transient pressures.

See Transients Advisor for further details.

Additional diagnostic messages in log file

Set this option to "Yes" to output additional information to the simulation log file.

This additional information includes UPC diagnostic messages.

Use Fast PST Variable Speed Pressure Control

Set this option to "Yes" to apply Fast PST Variable Speed Pressure Control.

This option improves stability when modelling pumping stations regulating pressure and may lead to fewer iterations.

If this option is set to "No", the method of calculation used in versions prior to version 8.0 will be used.

Allow Drain Down

Set this option to "Yes" to apply a progressive loss of supply to a node. The length of time it takes to drain a node is calculated based on the demand on the node as well as the loss of pressure.

If this option is set to "No", there will be no supply to the node once it is isolated.

Set this option to "Yes" to apply a progressive recharge of network areas previously drained or partially drained once it has been reconnected. The length of time it takes to recharge a link is calculated based on flow due to the pressure difference across the link with one end fully charged and the other either drained or partially drained. The calculated flow may allow more than one link to be refilled at a given time-step. This option will be applied only if Allow Drain Down has also been selected.

If this option is set to "No", recharge of reconnected and drained areas occurs instantly.