SewerGEMS - Lifting Pump station

Hello Rossouw,

I'm visualizing that your system looks like one of below sketches:

(A) Short pressure pipe discharging into gravity conduit that exits manhole

(B) Pressure pipe rises to the top of the manhole then continues downstream as a pressure pipe, flowing full

In either case, the manhole could be modeled as a Wetwell, with a "virtual" pipe rising up to a node set equal to the pipe exit elevation, then either a conduit or pressure pipe downstream. 

If your modeling case is like "A" above, consider:

The pressure pipes adjacent to the pump would have a user defined length near-zero (for example 0.1 m) and the "Is Virtual?" property set to "True". The transition node allows you to have an enclosed transition between the pipes (no vertical structure). So, the profile should look as you would expect. Headloss through the pressure pipe could be accounted for either by adjustment to the pump curve, minor loss coefficient on the downstream conduit, or you could select "false" for "Is Virtual?" for one of the pressure pipes and configure the diameter and minor loss coefficient to model the equivalent headloss (considering the very short length that will still need to be used in order to prevent profile display problems) 

With this configuration, if the pipes between the submersible pumps will be flowing partially full, then I would consider using the Implicit dynamic solver.

Here's a possible model setup for Option B:

This is similar to "A" accept the pressure pipe continues downstream instead of discharging to a conduit. The numerical solver should not notice much difference with this configuration and the profile should still look acceptable.

If you use this approach and you know that the pipe between these submersible pumps will all be flowing under pressure (when the pump is on), then you may want to consider using the GVF Convex numerical solver. The above screenshot was taken using the Implicit Dynamic solver but I tried it with the GVF Convex as well and got very similar results. The GVF Convex solver tends to be more stable in models with a lot of pumps and force mains.

Let us know if this helps and we'll document this in a Support Solution article.

Hello Rossouw,

I'm visualizing that your system looks like one of below sketches:

(A) Short pressure pipe discharging into gravity conduit that exits manhole

(B) Pressure pipe rises to the top of the manhole then continues downstream as a pressure pipe, flowing full

In either case, the manhole could be modeled as a Wetwell, with a "virtual" pipe rising up to a node set equal to the pipe exit elevation, then either a conduit or pressure pipe downstream. 

If your modeling case is like "A" above, consider:

The pressure pipes adjacent to the pump would have a user defined length near-zero (for example 0.1 m) and the "Is Virtual?" property set to "True". The transition node allows you to have an enclosed transition between the pipes (no vertical structure). So, the profile should look as you would expect. Headloss through the pressure pipe could be accounted for either by adjustment to the pump curve, minor loss coefficient on the downstream conduit, or you could select "false" for "Is Virtual?" for one of the pressure pipes and configure the diameter and minor loss coefficient to model the equivalent headloss (considering the very short length that will still need to be used in order to prevent profile display problems) 

With this configuration, if the pipes between the submersible pumps will be flowing partially full, then I would consider using the Implicit dynamic solver.

Here's a possible model setup for Option B:

This is similar to "A" accept the pressure pipe continues downstream instead of discharging to a conduit. The numerical solver should not notice much difference with this configuration and the profile should still look acceptable.

If you use this approach and you know that the pipe between these submersible pumps will all be flowing under pressure (when the pump is on), then you may want to consider using the GVF Convex numerical solver. The above screenshot was taken using the Implicit Dynamic solver but I tried it with the GVF Convex as well and got very similar results. The GVF Convex solver tends to be more stable in models with a lot of pumps and force mains.

Let us know if this helps and we'll document this in a Support Solution article.