I just started using the Flowmaster program (ver if relevant) to model a series of stormwater pipes which are almost certainly in a pressure flow situation based on a first round analysis using open channel flow which failed due to insufficient pipe capacity.

I completed my model yesterday by modeling each pipe between structures and noted that the hydraulic grade line easily exceeds the grate elevation for a lot of my structures and is thus overflowing. In these situations, I sort of brute forced the program to model the next pipe section by assuming the downstream hydraulic head was equal to the height of the water column at the downstream structure.

This isn't ideal as it doesn't account for losses due to pipe bends, structures, and other elements that can cause additional losses. I have previously created an Excel spreadsheet to model these sorts of losses, but it was a very complex spreadsheet created for another company that I no longer have access to.

Given that I previously made something like this with just Excel, it seems like Flowmaster should be capable of doing the same. Is it possible to use the program to model everything in the run in a single go so that losses are properly accounted for?

  • $\begingroup$ I don't know the answer to that, but I would recommend looking into using SWMM instead. It will use the St. Venant equations to solve pipes under pressure. Maybe flowmaster will do it too, just a thought. $\endgroup$ – RossV Oct 29 '19 at 22:53
  • $\begingroup$ @RossV Not familiar with that acronym. Please define. $\endgroup$ – Pyrotechnical Oct 30 '19 at 12:41
  • $\begingroup$ Flowmaster can certainly be used to model an entire pipe run. Is your specific problem with the elevation of the pipes? If this is so, a cylindrical rigid pipe has a pipe elevation vs length input where the user can specify the elevation change of a pipe. Given your friction modelling is correct, it should be able to estimate the losses just fine. $\endgroup$ – mechcad Oct 30 '19 at 17:45
  • $\begingroup$ @mechcad the manner by which I modeled my pipe run was via individual Pressure Pipe worksheets for each pipe segment and augmenting the inputs by setting P2 equal to the downstream water column. But this is clunky and neglects structure losses, so I'm not sure if the program has functionality to do this all in a single worksheet so that the losses are handled more appropriately. $\endgroup$ – Pyrotechnical Oct 30 '19 at 23:57
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    $\begingroup$ SWMM (Storm Water Management Model) epa.gov/water-research/storm-water-management-model-swmm $\endgroup$ – RossV Oct 31 '19 at 14:47

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