This tutorial will guide you how to set up an EFDC sediment model of the Yen&Lee experiment which measured bed topography and sediment sorting in a channel bend subject to unsteady flow conditions.
To summarize Yen & Lee experiment, 20 cm of noncohesive sand with known size gradation were placed in a laboratory channel bend with 11.5-m entrance and exit lengths, a central angle of 180° degrees, an inner radius of 4 m, and a channel width of 1 m. The channel was adjusted to a slope of 0.002 parallel to the center line. (The inlet is higher than the bend, which is higher than the outlet.) The base flow was 0.02 m3/s (corresponding to a water depth of h0 = 5.44 cm) and increased linearly to a different peak value for each run (i.e., run 1-run 5, where peak flow rates decreased with increasing run number) and then returned linearly to the base flow (Yen&Lee 1995).
Figure 1: Yen&Lee Experiment Run 1 Results
This model example will be constructed in EE8.3 using state-of the-art sediment transport sub-model SEDZLJ which has been developed by Sandia National Laboratories and now incorporated to EE8.3.
Figure 2 Generate EFDC Model and Import Grid Form.
4. Click Generate button and finish. A dialog will pop up to show the gird information (Figure 3)
Figure 3 New Created Grid Information.
5. Save the model by selecting this button and create a new directory (Figure 4)
Figure 4 New model saved.
This section will guide you how to assign the initial conditions such as the bathymetry, water level, and bottom roughness. You also learn how to prepare the boundary conditions like the inflow/outflow, temperature, and water quality.
Figure 5 Assigning the Initial Conditions.
Select the Domain/Initial Conditions & Bottom Roughness and under Bathymetry form click the Assign button. (See Figure 5).
In the Apply Cell Propeties via Polygons for Bottom Elevation select Bottom Slope – I Direction option and populate the Elevation and Slope fields as shown in Figure 6
Click to the Apply button to take the effect before hitting the Done button.
Figure 6 Assigning the Bathymetry.
This is to assign the initial depth or water surface elevations. There are two options for setting the surface water elevation there are Use Constant and Use Point Measurements/Gridded Data.
Under the Depth/Water Surface Elevations form click the Assign button
Figure 7 Assigning Water Surface Elevation.
Select Use Constant and populate the Operator or Constant field value of 0.054 (m)
Make sure the Assign Depths Instead of Water Surface Elevations option is checked (Figure 7)
Then, click Apply button then click Done button to finish
This section will guide you how to prepare for the boundary conditions and assign it to the model cell configuration. In this example, there are two flow boundaries; one is the discharge from the upstream of the bend and the other is a weir (Hydraulic Structure) at the end downstream. Thus, we should prepare a time series of inflow and a H-Q relationship table for this particular case. In order to set a boundary time series the following steps should be taken as;
Figure 9 Assigning Flow Boundary Conditions.
Figure 10 Editing the Boundary Time Series
6. Click to the Current button to view the current time series
Figure 11 Assigning Rating Boundary Conditions.
Figure 12 Editing the Rating Curve Time Series
Figure 13 Plot of Rating Curve.
When all required boundary time series are prepared. Users have to assign those boundary time series into the model cells. Figure 14 shows the location of inflow and weir for the Yen&Lee experiment.
4.3.1 Assigning flow boundary
In order to assign the flow boundary, the following steps should be taken
Figure 14 Assigning boundary condition cells.
Figure 15 Right mouse-click on the inflow cell.
Figure 16 Enter Boundary Group ID.
Figure 17 Select the Boundary Types.
Figure 18 Assign the corresponding time series.
Figure 19 Add to Adjacent Cells.
Figure 20 Assign inflow boundary.
4.3.2 Assigning Hydraulic Structure boundary
Figure 21 Enter Downstream Boundary Group ID.
Figure 22 Hydraulic Control Structure Boundary Conditions.
Figure 23 Add to Adjacent Boundary Cell.
Now the hydrodynamic model has been set. The users can save and run for a check.
However, users should add the sediment transport to this model as described in the Yen&Lee experiment.
Figure 24 Active Sediments Module.
Figure 25 Modify Sediments Setting.
Figure 26 General setting of Sediment and Sediment Bed Properties.
4. Set up the Sediment Bed tab as Figure 27.
Figure 27 Setting Sediment Bed.
5. Set up the Sediment Properties tab as Figure 28.
Figure 28 Setting Sediment Properties.
6. Set up the Erosion Rates tab as Figure 29.
Figure 29 Setting Erosopm Rates.
7.Set up Core Definitions tab as Figure 30
Figure 30 Setting Core Definitions.
8. Set up Core Assignment tab as shown in Figure 31.
Figure 31 Setting Core Assignment.
Contaminants tab / The user ignore this tab
Wave Options tab /The user ignore this tab
Select Timing/ Linkage and Model Run Timing (Figure 32)
Enter Duration of starting/ ending the simulation. Note that the boundaries time series should be always covered this simulation duration period. Otherwise, the model will not run
Figure 32 Model Run Timing.
This section runs the EFDC model and includes the following steps:
1. Select the Setting icon on the main EE form to browse to the EFDC Executable file (Figure 33). By default this file is in the installation folder C:\Program Files(x86)\DSI\EFDC_ExplorerXX
Figure 33 Browse to the EFDC executable file.
2. Select the Run EFDC icon on the main form and click the Run EFDC+ button to run the model.
3. If all settings are correct, the model will start running and users will see the MS-DOS Window appear showing the model results as shown in Figure 34
Figure 34 Run EFDC run window.
Note that you can press any characters on the keyboard to pause the simulation and check the model results. If you want to exit the simulation press the same key again if you want to continue the run then press any other key.