Applies To
	Product(s):	Bentley SewerGEMS, Bentley CivilStorm, Bentley StormCAD
	Version(s):	10.00.00.XX +
	Environment:	N/A
	Area:
	Original Author:	Mark Pachlhofer, Bentley Technical Support Group

Problem

Does StormCAD  (GVF Rational solver) use the momentum equation in the HEC-22 calculation for structure loss?

Solution

Older versions of StormCAD did not use the momentum equation when a pipe connection occurred, but with the CONNECT edition release of the product there is an option for using this equation. The screen shot below is from the Federal Highway Administration - Hydraulic Engineering Circular No. 22, Third Edition and explains more about this.

1.     2013, US Department of Transportation Federal Highway Administration - Hydraulic Engineering Circular No. 22, Third Edition: Urban Drainage Design Manuel. pg. 7-15, https://www.fhwa.dot.gov/engineering/hydraulics/pubs/10009/10009.pdf , August 05, 2016.