Using the Pressure Sensitive Demand option

Step-by-step guide

Hydraulic transients create rapid head fluctuation, and the system demand responds to the pressure changes in the pipe system. For a transient simulation to accurately reflect system dynamics, these demand fluctuations should be incorporated into the model; however, demands are typically modeled as constant—independent of both pressure and time—over short intervals.

To keep demands from remaining constant during the transient, InfoSurge has a Pressure Sensitive Demand option. This example runs a surge analysis with Pressure Sensitive Demand enabled to demonstrate how it impacts surge analysis results.

  1. Double-click the desired project .aprx file to open ArcGIS Pro.
  2. Click the InfoWater Pro tab to open the InfoWater Pro ribbon.
  3. In the Project panel, click Initialize.
  4. From the Model Explorer, click Run Manager.
  5. From the Run Manager dialog box, switch to the Surge tab.
  6. Enable Hydraulic Run Only.
  7. Click Run to perform a hydraulic simulation.

In the Model Explorer, the Run button highlighted in red; and in the Run Manager, the Surge tab, the Hydraulic Run Only option and the Run button highlighted in red.

  1. When the run is complete, deselect Hydraulic Run Only.
  2. Enable Pressure Sensitive Demand.
  3. Set the Exit Head to 0.
  4. From the Intrusion Calculation Method drop-down, select 0: No Intrusion Calculation.

A low-pressure transient event—from a power loss, for example—can potentially cause the harmful intrusion of untreated, possibly contaminated groundwater into pipes with leaky joints or cracks. Pathogens or chemicals close to the pipe can become a potential contamination source. In this example, calculations for potential contamination are not included. However InfoSurge is able to calculate the volume of intrusion due to low or negative system pressures.

  1. Click Run again to perform another surge analysis.

The Run Manager, Surge tab, with settings for this example configured and highlighted in red.

  1. Click OK to close the Run Manager.
  2. From the map, select Junction 10.
  3. From the Model Explorer toolbar, click Graph to view its pressure profile, noting the maximum pressure.

In two side-by-side-images, on the right, in the Model Explorer, the Graph button is called out; and on the left, the Report Manager displays the pressure profile for Junction 10.

Now, run the analysis without Pressure Sensitive Demand enabled:

  1. Reopen the Run Manager.
  2. Disable Pressure Sensitive Demand.
  3. Run another surge analysis.
  4. When complete, click OK.
  5. From the InfoWater Pro ribbon, View panel, click Report Manager.
  6. In the Report Manager dialog box, click Refresh All to update to the latest run results.

In the ribbon, View panel, Report Manager highlighted in red; and in the Report Manager, the updated pressure profile for Junction 10, with Refresh All highlighted in red.

Note the difference between the results with and without Pressure Sensitive Demand enabled.