Weirs design problems

I recommend setting the calculation option Active Numerical Solver to Explicit (SWMM Solvers).

I don't see what you described when using that solver.

I have already observed this solution, and it works. But the problem is that I need to use HEC-22 Energy headloss method, and it is not supported by SWMM solvers.

Here are some suggestions for an improved solution using the Implicit solver.

• Remove the control on "Waste water conduit". This control is redundant because the orifice diameter in the control is the same as the pipe diameter.
• Remove the control on conduit "Rainwater Outlet".
• Create a weir by completing the following:

Split conduit "Rainwater Outlet" with a transition

Before:

After:

Transition Properties:

 

Conduit/Weir Properties:

1. Remove headloss due to the conduits' bend angle at the transition.

Set the field "Has User Defined Bend Angle?" to True

Set the field "Bend Angle (User Defined)" to 0 degrees.

2. Set the conduit upstream of the transition to have section type Irregular Closed Section

3. For this example, I calculated the Chord Length for incremental elevations to create the cross section. Copy the following Elevation and Chord Length values (calculated in Excel) and paste them into the Depth Width Curve's Elevation and Width fields.

Invert Elevation = 1739.74 m

Weir Height = 0.1 m

Radius = 0.75 m

 

Elevation = Distance from Center + Height                

Chord Length = 2*SQRT((Radius^2)-(DistanceFromCenter^2))

Here is the profile after making the above changes.

Here is the profile after making the above changes.

Thanks for your help.