Objective - In this tutorial you will learn how to add culverts and perform test model sensitivity model cell size and hydraulic equation.

Data Files

The data for this tutorial are provided below.


These data are for demonstration purposes only and should not be used for engineering analysis.

Steps

Cell Size Sensitivity

  1. Run the plan called 100ft.
  2. Run a similar plan with a smaller cell size.
    1. Duplicate the Geometry (also called 100ft)
      1. (Right Click on the Geometry and Select Duplicate)
    2. Rename it to 50ft
    3. Select the new Conceptual Mesh and Choose the Components pane on the right.
    4. Select the Finer (0.5x) button under Global Cell Size Modification
    5. Regenerate Mesh.
    6. Run a new 50ft plan
      1. Copy the 100ft Plan
      2. Rename it to 50ft
      3. Change the Geometry to the 50ft Geometry you just made
      4. Compute
  3. Run a coarser mesh. 
    1. Rerun the steps above, except make the new Geometry and plan 200ft
    2. With the new geometry, press the Coarser (2X) button to make the mesh Coarser
  4. Compare the results.
    1. Synch your results
      1. Turn on the 200, 100, and 50 ft results.
      2. Click on the Group Heading ("Results")
      3. Move the scroll bar to the end of the simulation
      4. Switch the result to Water Surface Elevation from the drop-down list just below the scroll bar
    2. Then plot the time series together in several locations.

      No.  You will want to switch to water surface elevation.  Depth is the difference between the water surface and the minimum elevation.  The minimum elevation often changes more than the water surface as the cell size shrinks. 

    3. Look at a few profiles in addition to times series.
      1. Keep all three results on, and click on the Profile Line Feature.
      2. Draw a profile line, and right click on it.
      3. Evaluate the WSE and Velocity results.

    4. It is close in most places, but it would be worth running another size smaller.

  5. Try halving the cell size again. 
    1. How does this affect the result?
    2. What is a good cell spacing for this project?  


Test the Sensitivity of your Hydrodynamic Equation

We ran these models with the Shallow Water Equation on the CPU with advection but not turbulence. 


 Let's test the sensitivity of each term.

  1. Your 50ft plan will be the base plan.  Rename it to 50ft+Adv
  2. Duplicate it and rename to 50ft+Adv+Turb

  3. Turn the turbulence term on.
    1. Select the plan and choose Advanced Options.
    2. Switch on Use Turbulent Mixing
    3. This will enable the turbulence and mixing factors
    4. Compute
  4. Duplicate and rename the original plan to 50ft(NoAdvorT)
  5. Turn off advection.

    1. Select the plan and choose Advanced Options.
    2. Switch Use Advection off
  6. Compare the results.  How sensitive are they to the Shallow water equation terms?


Add a Culvert

Next we will add a culvert to drain the flooded area.
For this, we have provided a second geometry, boundary condition file, and plan that includes a channel that you can connect to.

  1. Run the Add Channel plan.
  2. Add a culvert
    1. Duplicate the geometry and Rename the new geometry to "Add Culvert" 
    2. Click on the Culvert Barrels layer
    3. Select the edit tool
    4. Connect the floodplain to the channel with a culvert by double clicking inside the levee and again in the channel
    5. Make sure your culvert connects full cells with standard volumes, not edge cells or cells that include the levee which will have small volumes
  3. Parameterize your Culvert
    1. Click on the Components pane on the right.  Culverts have three components.  Let's define the Barrel and Opening Properties first so we can select them later.
    2. Click on the Barrel Properties tab.
      1. Click on the green "+" to add Barrel Properties
      2.  Name the Barrel "Pipe"
      3. Delete Circle form the Shape field to see the list of shapes...then choose Circle.
      4. Give the barrel a rise of 4 and a span of 4.
    3. Click on the Opening properties and press the "+" to add one
      1. Call it "Gate"
      2. Give it entrance and exit loss coefficients of 0.5 and 1 respectively
      3. Delete the default Inlet Configuration to see the list of options.
      4. Select CircularCulvertSmoothTerperedInletThroat

    4. Select Culverts and double click on Culvert Barrel
      1. Select the Barrel Properties ("Pipe") and the Upstream/Downstream Openings ("Gate") that you just defined from the drop downs.
      2. Hover over the upstream and downstream terrain to find appropriate upstream and downstream inverts
    5. Compute
    6. View results
      1. To view results turn on the geometry and culver under the result
      2. Then right click on the culvert
      3. You can ask for a flow time series or standard time series results