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Historical SWMM 5 and SWMM 4 Engines and Examples

Subject:  Historical SWMM 5 and SWMM 4 Engines and Examples   The web site has http://swmm5legacycode.ning.com/  historical SWMM 5 installs, SWMM 5 input file examples and SWMM 4 input files and engines.   The SWMM 4 engines go back to SWMM 3.5…
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"Subject:  Historical SWMM 5 and SWMM 4 Engines and Examples   The web site has http://swmm5legacycode.ning.com/  historical SWMM 5 installs, SWMM 5 input file examples and SWMM 4 input files and engines.   The SWMM…"
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SWMM5.NET

15 GPM 1985 1D Components in InfoSWMM 2D 3 Types of Manholes in SWMM 5 and InfoSWMM 3 Types of Subcatchment Flow in SWMM 5 A Basic InfoSewer Wet Well A feedback loop involves four distinct stages A rise in Pipe Inverts Across a SWMM 5 Node A…
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RSA Animate - The Power of Networks

In this new RSA Animate, Manuel Lima, senior UX design lead at Microsoft Bing, explores the power of network visualisation to help navigate our complex moder...
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Robert Dickinson replied to Robert Dickinson's discussion How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5?
"Subject:   Link Iterations in the SWMM 5 Dynamic Wave Solution   Each of the links in the SWMM 5 network can use up to 8 iterations to reach convergence during a time step in the dynamic wave solution of SWMM 5.  The rules…"
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How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5?

Subject:   How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5? An explanation of the four St. Venant Terms in SWMM 5 and how they change for Gravity Mains and Force Mains. The HGL is the water surface elevation in the upstream and downstream nodes of the link. The HGL for a full link goes from the pipe crown elevation up to the rim elevation of the node + the surcharge depth of the node.  The four terms are: dq2 = Time Step * Awtd * (Head Downstream – Head Upstream)…See More
Saturday

How to Determine if your model is Unstable in SWMM 5 or InfoSWMM

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Subject: How to Determine if your model is Unstable in SWMM 5 or InfoSWMM


SWMM 5 and InfoSWMM has a good output feature in the RPT file that tells you the list of links with the highest flow instability during the simulation. If you look at the link flow with the highest instability value and it looks okay to you then it usually means the rest of your model output is stable. The index is the number of flow turns for the link during the simulation. A flow turn occurs when


  1. We call DQ the difference between the New and Old flow,
  2. The value of DQ is greater than 0.001 cfs (we do not want to count small perturbations),
  3. The sign difference between the new DQ and the Old DQ is negative. In other words we want to count those oscillations in which the DQ value was negative and is now positive or was positive and is now negative. We don’t count then when the flow is monotonically increasing or decreasing in the link.


For example, the Link U-104 below has a large number of Flow Turns but a plot of the link flow shows the Flow Turns to mainly unimportant.

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Tags: How to Determine if your model is Unstable in SWMM 5 or InfoSWMM

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Comment by Robert Dickinson on November 30, 2010 at 9:33pm
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Comment by Robert Dickinson on November 30, 2010 at 9:33pm
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