Difference between Initial and base water quality constituent concentration types

Product(s): Bentley WaterGEMS, WaterCAD
Version(s): 08.11.XX.XX
Area: Modeling


What is difference between Initial concentration and base concentration, Water Quality, Constituent
Problem ID#: 67477


Initial concentration is the concentration at the element at time 0 i.e at the start of the constituent analysis. In many cases one will not know this initial value and will have to run an analysis for sufficiently long a period as to attain a solution where equilibrium has been reached. (If you have some idea about what the initial concentration might be it will be used by the software to reduce the time for the simulation to reach equilibrium. )

Whereas Concentration (Base) is a value associated with the element that is a constituent source, for that you need to select “True” for field “Is Constituent Source? “in the element properties.

You can either specify the “Concentration (Base)” value or setup the following 3 booster types:

1. Flow paced booster: Adds a fixed concentration to that resulting from the mixing of all inflow to the node from other points in the network.

2. Concentration: Fixes the concentration of any external flow entering the node such as reservoir flow or negative demand (inflow). You would use this when you know the concentration of a flow source into the system.

3. Set point booster: Fixes the concentration of any flow leaving the node (as long as the concentration resulting from all inflow to the node is below the set point). So, this will adjust concentration up, but not down if it is already higher than the set point.

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