"At the Summit of Olympus Mons
Credit: G. Neukum (FU Berlin) et al., DLR, ESA
From martian orbit, the Mars Express cameras looked down on the largest volcano in the solar system. The result was this stunningly detailed overhead view of the…"
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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…"
Robert Dickinson left a comment for wu ze jian"Hi, I added this discussion http://swmm2000.com/forum/topics/how-is-the-st-venant-equation-solved-for-in-the-dynamic-wave-solu"
Robert Dickinson posted a discussionHow 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
Robert Dickinson added a page to the group Hydraulics
Force Main Friction Loss in InfoSWMM and the Transition from Partial to Full Flow
Subject: Force Main Friction Loss in InfoSWMM and the Transition from Partial to Full Flow
You can model Force Main friction loss in InfoSWMM using either Darcy Weisbach or Hazen Williams as the full pipe friction loss method (see Figure 1 for the…
Robert Dickinson's blog post was featuredSWMM 5 Precipitation Options
Subject: SWMM 5 Precipitation Options You can have design storms, monitored storms of any length of the time from minutes to centuries, use intensity, volume or cumulative precipitation, use both rainfall and snowfall in the same rain gage depending on temperature, use both time series or external files for the rain gage and have unlimited rain gages with the limitation of one rain gage per subcatchment. …See More
Robert Dickinson posted a blog postSWMM 5 Precipitation Options
Subject: SWMM 5 Precipitation Options You can have design storms, monitored storms of any length of the time from minutes to centuries, use intensity, volume or cumulative precipitation, use both rainfall and snowfall in the same rain gage depending on temperature, use both time series or external files for the rain gage and have unlimited rain gages with the limitation of one rain gage per subcatchment. …See More
Robert Dickinson commented on Robert Dickinson's group Stream of Information"Pacheena Indian Reserve, British Columbia, Canada
May. 25, 2012
"
Robert Dickinson commented on Robert Dickinson's group Stream of Information"All the Water on Europa Illustration Credit & Copyright: Kevin Hand (JPL/Caltech), Jack Cook (Woods Hole Oceanographic Institution), Howard Perlman (USGS)
Explanation: How much of Jupiter's moon…"
Robert Dickinson commented on Robert Dickinson's group Water Quality"URBAN STORMWATER QUANTITY/QUALITY MODELING USING THE SCS METHOD AND EMPIRICAL EQUATIONS†
http://onlinelibrary.wiley.com/doi/10.1111/j.1752-1688.1997.tb04093.x/abstract
May 24, 2012
Wiley Online Library will be disrupted on 26 May from…"
Robert Dickinson commented on Robert Dickinson's group Water Quality"Hi MeHa, Here is one good source of data, I also have the SWMM 5 models for the USGS areas.
http://www.1000friendsofflorida.org/pubs/stmarksgreen/apend4.asp
http://sofia.usgs.gov/publications/ofr/78-324/ofr-78-324.pdf
"
MeHa commented on Robert Dickinson's group Water Quality"I want to model WQ of sewers. Can any body provide me a network with real measured calibration files? "
MeHa posted a status"Hello, When designing a sewer system, we consider the Node Flooding and Conduit surcharge in the status report. Is there any guideline which"
Quah Soon Tong left a comment for Esther Bergareche Auricenea"Hi Esther, I am not sure you are the same Esther that was at the United World College in South Wales with me. I am Quah Soon Tong from Singapore. I noticed you are also an engineer. I did Civil Engineering at Cambridge University, but practised as…"
Robert Dickinson commented on Robert Dickinson's group Stream of Information"River Canyon
May. 23, 2012
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Robert Dickinson commented on Robert Dickinson's group Stream of Information"Litla Dimun, Faroe Islands
May. 23, 2012
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The Keep and Dampen options and their effect on the four main terms of the St Venant equation
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Note: The Keep and Dampen options and their effect on the four main terms of the St Venant equation.
The four terms are are used in the new flow for a time step of Qnew:
Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1)
when the force main or gravity main is full dq3 and dq4 are zero and Qnew = (Qold – dq2) / ( 1 + dq1)
The dq4 term in dynamic.c uses the area upstream (a1) and area downstream (a2), the midpoint velocity, the sigma factor (a function of the link Froude number), the link length and the time step or
dq4 = Time Step * Velocity * Velocity * (a2 – a1) / Link Length * Sigma
where Sigma is a function of the Froude Number and the Keep, Dampen and Ignore Inertial Term Options. Keep sets Sigma to 1 always and Dampen set Sigma based on the Froude number, Ignore sets Sigma to 0 all of the time during the simulation
the dq3 term in dynamic.c uses the current midpoint area (a function of the midpoint depth), the sigma factor and the midpoint velocity.
dq3 = 2 * Velocity * ( Amid(current iteration) – Amid (last time step) * Sigma
dq1 = Time Step * RoughFactor / Rwtd^1.333 * |Velocity|
The weighted area (Awtd) is used in the dq2 term of the St. Venant equation:
dq2 = Time Step * Awtd * (Head Downstream – Head Upstream) / Link Length or
dq2 = Time Step * Awtd * (Head Downstream – Head Upstream) / Link Length
Normally, dq1 (Friction Loss / Maroon in the Graph) balances dq2 (Water Surface Slope Term or Green in the Graph) but often for links with a large difference between upstream and downstream depths dq4 (Red in the Graph) can have a significant value. If dq4 or dq3 are important then the depth of water to increases to pass the same flow using the Keep option over the Ignore. If you have a link with a Froude number near or over 1.0 (Supercritical) then using Keep or Dampen for the Options may result in depth differences. The effect of Keep is to increase the “loss” terms in the St Venant Equation. The effect of Dampen and Ignore is to decrease the sum of the “loss” terms in the St. Venant Solution and lower the simulated depth.
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