Flow in pipes

Question

Hello, 
 
 I'm new to WaterCad and I'm wondering if it can help me with my problem. I have a tank which has an exit line that branches into three lines and I want to know the flow that would exit my tank and the amount of flow that passes through each pipe. The three branches have different diameters and end at different elevations. Do anyone has any advice? 
 
 Thanks in advance.

Tom Walski · Accepted Answer

Yes, and that would be the answer for the case when you have no pressure at the end of the pipe. If you want to know the flow when you have say 20 m of head at the end, then just add 20 m to the water level t the downstream tank.

Jose Valladares · Answer

Tom Walski said: Let's say the source tank water elevation is 800. If the downstream tank water level is at 750, then you will get flow X. If it is at 700, you will get more than X. It depends on the difference in HGL between the two ends. 
 Exactly, that's what I want to know. The amount of flow that each branch will get depending of their HGL and pipes diameters.

Sushma Choure · Answer

Hello Jose, 
 As explained by Dr. Tom to understand if the total demand can be supplied or not you need to enter demands in the model as WaterGEMS / WaterCAD is a demand driven software. 
 However if you are having tank in the model, then as per the capacity of tank you can see how much flow it can supply without entering demands, you can see that in tank properties. 
 Here is learning resource guide for WaterCAD / WaterGEMS for your reference. 
 Learning Resource Guide for new users of Bentley WaterGEMS and WaterCAD

Jesse Dringoli · Answer

As Tom mentioned, there isn't a single answer, because there can be an infinite amount of flow through a given pipe at an infinite headloss. 
 Maybe you want to know how much flow can pass through the pipe without violating a minimum pressure constraint? If so, try right clicking on the downstream junction and choose " hydrant flow curve ". This will show a range of flow and the corresponding pressure. 
 If you want to assume a certain diameter opening to the atmosphere at the pipe end, and see how much flow will pass through the pipe based on the capacity of the opening to discharge flow, then this is more of a pressure dependent demand (PDD) problem, and you can try setting up a PDD demand on the node, an emitter coefficient, or a Discharge To Atmosphere, depending on the data that you have.

Flow in pipes

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