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surcharge flow in SWMM 5

i'm trying to find out, how works the surcharge flow in SWMM 5. Another programm (like Infoworks) use preissmann slot to simulate Surcharge flow in closed coduit. which approach is accurate? Could you give me some informations about this, robert? thanks a lot!

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  • Yes, it has those capabilities

    Subject:  SWMM 5 Threshold Groundwater Elevation

    A large difference between SWMM 5 and SWMM 4 is how the Groundwater Aquifer interacts with the drainage network.  In SWMM 4 since the hydrology was simulated in the Runoff Block, the results saved to an interface file and the hydraulics were simulated in the Extran Block it was not possible to have a time step to time step interaction between the Aquifer and the Open Channels.  SWMM 5 has integrated hydrology and hydraulics so it is possible to use either a fixed Threshold Groundwater Elevation for each Subcatchment or the Receiving Nodes Invert Elevation.



    Image002
    Subject:  The Groundwater flow in SWMM 5 Groundwater

    The Groundwater flow in SWMM 5 is actually made up of three components:

    1.   A groundwater flow computed from the coefficient a1 and exponent b1
    2.   A groundwater flow computed from the coefficient a2 and exponent b2 and
    3.   A Surface Water / Groundwater Interaction coefficient a3
    The total Groundwater flow is the sum of the flow from 1, 2 and 3 – normally 2 is the opposite of 1.

  • Another thing I was interested : Can swmm simulate the groundwater infiltration and surface water inflows ?  can I use SWMM simulate a region and then I misconnect or split some pipes to see the changes of flow and depth in conduit and junctions?  

  • In SWMM5 you can do a scatter graph of the flow in a link versus the depth in a link, the curve will typically be looped as you get different flows for a depth as the flow is increasing and decreasing due to different upstream and downstream values for the cross sectional area, hydraulic radius etc1058530841.png?width=721

    Subject: Hysteresis Effect in the Link Flow versus Depth Relationship in SWMM 5
    You can often get a hysteresis effect for the Flow versus Depth relationship in SWMM 5 due to the five component St. Venant equation used to simulate the flows (http://swmm5.blogspot.com/2010/12/what-are-units-for-five-st-venant...) . A hysteresis effect is having two or more flow values for the same depth value in the link. For example, this image shows how the link 8100 has a different flow for the same depth in the rising and falling limb’s of the hydrograph. This is due to the different values for the upstream and downstream head, hydraulic radius and cross sectional area during the falling and rising hydrograph, respectively.
    image002.png.scaled.500.jpg
  • the junction is upstream of the conduit, and they are closely linked. It seems they really have some special relations which can be described by a formula.

  • Try looking at this discussion which at least shows what is in the Mindmap without the ability to manipulate the HTML code. This site uses Java but my apologies for your difficulty,

    http://swmm2000.com/forum/topics/swmm5-mindmap-without-html

    • Is there a method in finding analytical solutions to Saint - venant equations in simple cases? For example, I want to know the relationship of flow in one conduit and depth in a junction which is the upstream of the conduit. According to the simulation of SWMM, I find it does have some relation, but I wonder if there is an formula to describe the relation.

      • It is really pretty simple, the change in the node depth is dH/dt = Sun Net Flow / Sum Area

         


        Subject: What is Node Convergence in SWMM 5?
        If a link has converged within two iterations then the hydraulic computations will be bypassed for the link in new iterations. A link is deemed converged if BOTH the upstream and downstream node depth has converged between successive iterations as long as two iterations have occurred during the time step. The nodes are considered converged if the depths between successive iterations is less than the stop tolerance of the program (the default stop tolerance is 0.005 inches). The new node depths are ALWAYS computed for each iteration but the links connected to the converged nodes may bypass computations and save on simulation time. Note: If the nodes ever become non converged after 2 iterations then the link flows will be computed.
        1058530866.png
        1058530870.png

         
        • Can we get a relation of depth in Node and flow in link whose form is like Q=f(h,n,s,L,R), where h is the depth in a Node, Q is the flow in a link,  n is the Manning N, s is the slope, L is the Length, R is the radius. Or Q=f(h) when n,s,L,R is given. The following figure shows the regularity of H and Q. The curve varies by the parameters as R and L .

          1058530875.png?width=721

  • Hi, do you mean the mindmap or the books link = either way it will involve options on your computer.  Let me see if there is a way NOT to use Java for either.

    • it is the mindmap link that cannot be opened. I installed java, but the problem remained.

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