HI,I'm working on my college project (The project is a plumbing system to drain a 1-m3 tank in the shortest time ). I use the discharge to atmosphere element at the end of the project but I'm really confused with this element's input data like [Flow (Typical) & Pressure drop (Typical)]. I don't know what is this inputs means I just have the elevation of the discharge point and pressure. I read (Modeling Reference - Discharge To Atmosphere) still got no answer. I also want to know is there a feature in WaterCad can Compute time to Drain or Empty a Tank.
Hello Mohamed,
The flow typical value would the amount of water going out of the D2A element. You can observe the calculated demand and corresponding pressure at the junction, then use that for the "typical flow" and "typical pressure drop" setting of the D2A.
Here is related discussion for your rererence about D2A,
Discharge to atmosphere query
About how much time does a tank to drain, for this purpose you need to run an EPS simulation until the tank drains and the system is depressurized.
Regards,
Sushma Choure
Bentley Technical Suppport
Sushma Choure, Thank you for your help.But I don't fully understand what you mean. Do you mean that I should replace the D2A element with Junction and see Junction pressure = drop pressure typical of D2A & Junction demand = Typical Flow of D2A ??! And how can I get the junction demand ??
This link has information on using the discharge to atmosphere element in WaterCAD: How does WaterGEMS/WaterCAD treat the discharge to atmosphere element? This includes information on entering the typical flow and typical pressure drop for the element.
Scott
If the only information you have about the outflow is that it is a pipe end open to the atmosphere, you could estimate the "typical flow" and "typical pressure drop" using the orifice equation based on the diameter/area of the end of the pipe. You'll have to select an estimated flow that you believe will be roughly the flow that will occur, then calculate the corresponding flow using the orifice equation. There is a note about this approach in the articles referenced by my colleagues.
If the pipe enters the tank below the water surface in the tank, try the tank element instead.
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.