Dear Infowater Experts,

I am recently baffled with yet another “model run result” I’ve been experimenting on.

Here is the situation;

I have an area with some nodes with preloaded demands. These demands have “zero” multiplier for their consumption pattern for 0:00hr to 24:00hr. For the succeeding hours however, they will have the usual varying consumption pattern (meaning non zero multiplier). I have also put controls on the pipes that supplies the area, which is closed during 0:00hr and open on 25:00 hr.

This consumption pattern and controls were intentionally imposed to show an alternating/intermittent/cycling (or whatever you call it) supply on my hydraulic network.

My question is; how come some of the nodes on this area have negative pressure while others have positive pressure. I was expecting that the entire area would have either “zero or negative pressure” but not positive pressure.

I’ve checked all possible entry points for water to supply the area, but all of them are closed. I even have the initial status of the “controlled supply pipes” with “closed initially” instead of the “none” status. What’s even weirder is when I displayed the flow arrows to check if there’s really flow, it shows that some pipes don’t have the flow arrows(which was what I have expected) and some have flow(which shouldn’t be). Below is a snapshot.


To check if there's no real possible source, I've made a sample and replaced the consumption pattern of a node with a positive consumption multiplier to check if it will disconnect, and as expected as I run it, it showed disconnection because it doesn't have any source.

Please shed me some light.