Dear Bentley,
I have assigned emitter coefficients to the nodes in my model to represent the leakages of the system. Emitter coefficient was calculated using the equation Q=k*P^n
However model results show a negative demand in some nodes where there are negative pressures. The reason I supposed is that the emitters create an inflow when the pressure is negative, which does not happen practically.
Is there a method to limit the minimum emitter discharge to 0, without giving negative discharges when nodal pressure goes negative?
Thank you,
Harsha
You can install a check valve in the pipe just before the emitter to allow flow in only one direction.
If you have a situation where the emitter it not at the end of a pipe and you cannot use a check valve, you can either place a short pipe at a tee, add the emitter at a junction at the end of the lateral tee pipe, and place a check valve on that pipe, or you can consider using Pressure Dependent Demands (PDD). PDD is a bit more complex to set up, but you can fairly easily configure it to follow the emitter coefficient relationship, then have it apply to only a selection set of elements where you wanted the emitters. See:
Pressure dependent demands and negative pressure
Using Pressure Dependent Demands
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.