Based on the law of continuity if there is a series of pipes with 10 nodes for example and there is no demand at any of the nodes on the pipe the flow that passes through the 1st node in that pipe series would be the same as that passing through the last node in that series.
But then say if node 5 in that same series of pipes has a demand. Then the flow that passes through the last node would then be the flow at the beginning of the pipe series minus the demand at node 5.
Or in other words when you assign a demand to a node that node then becomes a point where water is viewed by the model as being consumed.
Question?
Now say in reality the water is not consumed at node 5 but there is a branch downstream of node 5 with multiple customers which produces this demand at node 5. If it's the case that I do not need to know the pressures/pressure drops within the branch downstream of node 5 I could simply assign the demand associated with that branch to node 5 and eliminate that branch from my model right?
Or in other words what you need to consider when deciding whether or not to remove a branch is whether or not you will need to extract information (pressures) from that branch. If the answer is no you could pretty much remove that branch from the system as long *** you assign the branches demand to the upstream node right ?
So a requirement for the model I am creating is that the model retains a 1 to 1 relationship with the GIS map of the network. Now in the GIS map there are branches connected to pipes but the pipes in GIS have not been snapped at the point where the branch connects to the pipe (see image below). Now what I want to do is simply replace the branch with a lateral with the same demand as the entire branch. However the question that arises is, at what point (at how much demand) does it impact the accuracy of your model when distributing among nodes. Or in other words how much demand can you distribute among nodes before it significantly affects the accuracy of your model?
Hello Christen,
Are you planning on using customer meters and laterals/taps instead of junctions and pipes for these parts of the model? If so, the demands on the customer meters will still apply to existing nodes and pipes in the model, so the demands will still be accounted for. Hydraulic results would not be available for the lateral, though there is a calculation option where you can display some hydraulic results for the customer meter.
Regards,
Scott