Problems with pressure dependent demand functions and piecewise linear table

  Applies To 
Bentley WaterGEMS,  Bentley HAMMER, Bentley WaterCAD
  Version(s): 08.11.XX.XX
  Environment:  N/A
  Original Author: Mark Pachlhofer, Bentley Technical Support Group


When setting up a piecewise linear pressure dependent demand function I see a red notification in the lower left corner that says, "duplicate values for percent of reference demand" and my PDD results do not seem to follow their curve even though the model is balanced.


When setting up a piecewise linear table of percent of reference pressure vs. percent of reference demand and you want to flatten the last two values to have a flat top make the second to last row values 99.99% for both the percent of reference pressure and the percent of reference demand and the last row 100% for both inputs. In order to do this you should make sure the precision for each column is set to a value of 2. You can change the precision value of decimal places by using the units and formatting feature. Please refer to this wiki for directions on how to do that if you're not familiar

Please also note that it is assumed that any value entered over 100% is equal to 100%, so there is not a need to enter values larger than this.


See Also

Setting up pressure dependent demands

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