Design change between Steady state and EPS in large networks

Hello Amudhu,

Which product are you using? SewerCAD / StormCAD / SewerGEMS? or WaterCAD / WaterGEMS?

Are you (or the designer) using Darwin Designer to design pipes in WaterGEMS?

If you are designing a system it will be only designed in "Steady State" analysis and not in "EPS" since there are flow and velocity changes over time in an Extended Period Analysis (EPS) and optimizing a single pipe diameter for a range of flow values is difficult. In WaterGEMS if you are using the Darwin Designer, you should run your analysis in "Steady State".

Hope this helps.

Hi Joshi! Thank you very much

It's Watergems being used for the design. I understand that both steady state and EPS give the same result before optimisation or in other words just to meet the demand / loads in the system. If optimisation is done using Darwin designer then steady state will help us to fix the diameters.

In our case it's the existing system and have to meet the performance standards. Therefore optimisation need not be done and to study the behaviour of the system over a period of time (in a day) to meet the performance standards then EPS should only be done.

Please confirm

Hello,

Darwin Designer is only used for steady state runs, as it is looking at discreet time steps. See this link for details: Can I use Darwin Designer for the EPS analysis?

For more information on Darwin Designer, including tips and troubleshooting, please see this link.

Regards,

Scott

Mr. Kampa and Mr.Joshi

Thanks for more details

I have a continuation of the last clarification. I do only review and my designer has not designed the system using Darwin designer. He can run both steady state (SS) and EPS. But he claims that the pipe diameters have changed. Please reply for

1. Since it is an existing system, the proposed pipes can be approx using A=Q/A and checking with EPS will be more appropriate for both capital cost and meeting service levels. Yes or No

2. The diameter of pipes do not change because whether it is SS or EPS mode they are only tools to study the behaviour of the system and will not implicate on diameters

Hello Amudhu, 

Thank you for confirming that you haven't designed system pipe diameters using Darwin Designer and its an existing system. 

Do you mean that while switching between two scenarios SS and EPS the pipe diameters changed upon computing the model? Can you please confirm if you are using different physical alternatives for these 2 scenarios and these different physical alternatives might have different pipe diameters? 

Uploading model files for our review might help in this case, to help you further. Please mention elements / scenarios in question.

Sharing model files

About checking pipe diameters of existing system for EPS, yes indeed that is required to make sure provided pipe diameters are providing required flow and demands are satisfied throughout duration. 

Hello,

There is a tool called Scenario Comparison that you can use to see the differences between scenarios. So if there is a difference in the physical scenarios, as mentioned by Sushma above, you will be able to see which elements are different. If you want to review a model with the same pipe diameters with both a steady state and EPS run, you would want to make sure the same physical alternative is used in the two scenarios.

If that doesn't help, the model files would be needed, as noted in the Sushma's post above.

Regards,

Scott

Hello,

There is a tool called Scenario Comparison that you can use to see the differences between scenarios. So if there is a difference in the physical scenarios, as mentioned by Sushma above, you will be able to see which elements are different. If you want to review a model with the same pipe diameters with both a steady state and EPS run, you would want to make sure the same physical alternative is used in the two scenarios.

If that doesn't help, the model files would be needed, as noted in the Sushma's post above.

Regards,

Scott