Model results are different between the GVF-Convex and the Implicit/Explicit solvers

Applies To 
Product(s): SewerCAD, SewerGEMS, CivilStorm
Version(s): CONNECT Edition, V8i
Area:  Modeling
Original Author: Scott Kampa, Bentley Technical Support Group

Problem

The model results are different between the GVF-Convex and the Implicit or Explicit solvers.

Problem ID#: 54193

Solution

This is expected. The Implicit and Explicit solvers are dynamic wave solvers (found in SewerGEMS and CivilStorm) used to calculate runoff hydrographs from catchments and analyze the hydraulic response through interdependent systems of inlets, pipes, channels, culverts, and ponds. GVF-Convex solver (found in SewerCAD, as well as SewerGEMS) is used to design and analyze gravity and pressure flow through pipes and pumping stations.

Since it is a sewer system program, SewerCAD does not utilize ponds or rainfall data, like SewerGEMS and CivilStorm do. SewerCAD is very good at modeling complex pumping situations. As mentioned above, SewerCAD can also be used to aid in the design of a sewer system. It can also calculate a system in both extended period simulations and steady state situations.

SewerGEMS and CivilStorm are used for complex stormwater systems. It uses rainfall data entered by the user to calculate runoff into the system. It is strictly an extended period simulation program and will not design a stormwater system, but for dynamic systems, which changes in storage and flow.

With the substantial difference between the design and use of the programs, and in the calculation engine regime, it is expected that different will be obtained between the two programs, even for a similar setup.

See Also

Differences between the solvers: GVF-Convex vs. GVF-Rational vs. Implicit vs. Explicit (SWMM)

  • Created by Bentley Colleague
  • When: Tue, May 12 2015 5:40 PM
  • Last revision by Bentley Colleague
  • When: Tue, Nov 13 2018 11:41 AM
  • Revisions: 4
  • Comments: 0
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