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How to model a Water Suply Fountain and to add demands

Hi !

I want to model a water suply fountain, my doubt is do i model this element as a hydrant or as a junction?

The other doubt is:

I pretend to model a network with the total flow of 121 L/s, this flow can be divided into:

-real flow water losses (4.19 L/s)

-flow to apartments (6.79 L/s)

-flow to water fountains (57 L/s) (total number of 76 water fountains)

-flow to outskirts areas with houses (53,45 L/s)

I want to model a unit demand flow per lenght to the apartments areas and to the outskirts areas with houses, (i.e. L/s/m). So i should left the base demand to 0 L/s in the junctions of this 2 groups and create a unit demand , right?

Should i use the unit line method to model this traveling unit demand?

To model the water fountains should i treat this element as a junction and add the base demand or as an hydrant?

Regards

Miguel

  • Hi Miguel,

    I want to model a water suply fountain, my doubt is do i model this element as a hydrant or as a junction?

    The method to model this outflow depends on what you would like to assume. If you would like to assume a fixed flow rate (demand) regardless of the pressure, you could place a demand on a junction.

    If the outflow varies significantly with pressure, you could consider an emitter coefficient on a hydrant, the discharge to atmosphere (D2A) element, or pressure dependent demands (PDD). See more here: Options for modeling an outflow that varies with pressure

    I want to model a unit demand flow per lenght to the apartments areas and to the outskirts areas with houses, (i.e. L/s/m). So i should left the base demand to 0 L/s in the junctions of this 2 groups and create a unit demand , right?

    A junction can have pattern-based demands (base flow + pattern), or it can have unit demands (number of units plus unit demand), or it can have both. If you only want to use unit demands on a junction, then you would simply create the unit demand - by default, there will be no demand entry at all for a junction. If you already tried adding a pattern-based demand on a junction and you want to replace it with a unit demand, you would delete that pattern-based demand, then add the unit demand. This adding and removing can be done from the "demand collection" and "unit demand collection" fields in the junction properties, or in the demand control center / unit demand control center. Note though that unit demands require you to enter the number of units, and the amount of demand per unit - it doesn't look at the pipe lengths. See also:

    Unit demand control center Vs. Demand control center

    How can I add nodes to the Demand Control Center so that the demands can be inputted?

    Should i use the unit line method to model this traveling unit demand?

    Although the Unit Line method in LoadBuilder is intended to distribute unaccounted for demands (such as leakage and other non-revenue water), you may be able to use it for the purpose of distributing demands based on pipe length. See: LoadBuilder: Allocate demands based on pipe length


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

  • Miguel,

    What exactly is a "fountain" in your terminology. Is it something that runs 24/7 (emitter) or does a consumer need to turn it on and off (demand)?

    Unit demand in WaterGEMS are based on number of units assigned to junctions (number of houses, number of restaurant tables, etc.) not length of pipe. We have a method that can assign demands based on polygons around nodes in undeveloped area where the polygons can be automatically generated using Theissen polygon).

    Is that 121 L/s the peak instantaneous demand, peak day demand, average day demand? You need to make sure it can deliver water under high and low demand times.

  • Hi Tom!

    It's not a 24/7 emitter, the consumer needs to turn it on and off demand. Something like this:

    it should be model as a junction?

    I'm trying to run a Steady State Anyisis , i'll start with the year 20 flow (316 L/s) (peak day).

    And i previously know from an excel sheetspread the total consumption in each pipe. I should use the consumptions from that excel and apply this formula base on the flow in each pipe to determine the base demand for each junction, right?

    Based on your information the easiest way to model this unit demand per lenght is to add as a base demand to a junction, right?

    Regards

  • WaterGEMS has a large collection of different methods for allocating demand to nodes.

    If it is a small system, you can allocated demands manually in the Demand Control Center. If it is a larger system, users usually rely on LoadBuilder. In some situations, a user may apply one method to the existing system and another to future growth areas.

    My suggestion is to read the help for the methods. In particular "Allocating Demand Using Load Builder" and determine which method bet fits the data you have.

    If the fountain is manually controlled, I would treat it as a junction with demands rather than a flow emitter.

  • Hi Tom! Thanks for your help

    I've followed your advice to model it as a junction, thanks!

    I'm almost reaching the 123 L/s flow, now i got 2 questions

    Can i add the real water leakage flow to the entire network of 4,19 L/s using LoadBuilder or can i add this leakage flow using a different option?

    Now i want to model the year 20 flow, once that i already got the base demand in each node there's any simple way to reach this total flow of 316 L/s ( Flow to water fountains 69,444 L/s ; flow to apartments 92,58 L/s and flow to outskirts 154,308 L/s), there's any easy way to get this demands? I will upload the model if it could help

    Thanks for your support