Yen & Lee U-Shaped Flume SEDZLJ Sediment Model (Level 2 Step-by-Step Guidance)

1. Introduction

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.

2. Importing Grid

  1. Open EE
  2. Click Generate New Model icon as   on the main menu of EE interface. Then Generate EFDC Model frame appears shown in Figure 2 (below).
  3. Select Delft RGFGrid in the Grid Type. Users click Browse button to select the grid file name as Yen&Lee.grd as shown in Figure 2. EE support the user to import various format of Grid file by using option Import Grid

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.

3. Assigning the Initial Conditions

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.

3.1 Assigning the initial bottom 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.

3.2 Assigning the Depth/Water Surface Elevations

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

4. Assigning the Boundary Conditions

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;

4.1 Preparing the Flow Boundary.

  1. Select the Domain/Boundary Conditions. ( Figure 9).
  2. Click to the E button  which is next to Flow to edit the flow boundary. (Figure 9)
  3. Entering the Number of Series into the box (in this case, enter 1)
  4. Give a Tittle for associated time series.
  5. Copy and Paste the time series data into the workspace. (Figure 10).

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

4.2  Preparing the Rating Curve Boundary.

  1. Click to the Rating Edit button as shown in Figure 11
  2. Entering the Number of Series into the box (in this case, enter 1) and give a Tittle for associated time series.
  3. Copy and Paste the time series data into the workspace as shown in Figure 12
  4. Click the Current button to see the rating curve as shown in Figure 13

Figure 11  Assigning Rating Boundary Conditions.

Figure 12   Editing the Rating Curve Time Series

Figure 13  Plot of Rating Curve.

4.3   Assigning Time Series to the Boundary Location Cells.

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

  1. On the main form of EE click to the 2D Planview icon 
  2. Choose Boundary C’s in the Viewing Opt’s ( Figure 14).
  3. Check Enable Edit and Show Grid  (Figure 14).
  4. Right-Mouse-Click on the inflow location cell/ choose New (Figure 15).
  5. Enter the boundary group ID: Inflow group (Figure 16).
  6. Select boundary types. It is dependent on your current boundary type to choose the suitable boundary type. In this case, we have 1 flow boundary so we choose number 1 (Figure 17).
  7. Select the flow table associated with this inflow boundary time series from the dropdown list (Figure 18).
  8. Click OK to complete. 
  9. The boundary cells might have multiple cells. In order to assign the next cell as inflow cell, you need to come back to step 4 and Right-mouse Click to that cell and choose to Add to Adjacent. The inflow is now divided into the number of assigned cells (Figure 19 and Figure 20).

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

  1. Right-mouse click on the downstream end ( Weir location in Figure 14 ) and choose New
  2. Enter the Boundary Group ID: DS Weir (Figure 21)
  3. Select boundary types: 2 (Hydraulic Structure/ Flow Table)
  4. Select the H-Q table that we have prepared (Figure 22)
  5. Add more adjacent boundary cell as shown in Figure 23

Figure 21  Enter Downstream Boundary Group ID.

Figure 22  Hydraulic Control Structure Boundary Conditions.

Figure 23  Add to Adjacent Boundary Cell.

5. Generate a SEDZLJ sediment transport model

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.

  1. Go to Active Modules tab, check on boxes to activate SEDZLJ sediment ( Figure 24), the Sediments tab will be added to the left-side tab
  2. Click Sediments tab on the left-side tab then click Modify button ( Figure 25).
  3. A form of Sediments and Sediment Bed Properties appear, the users put the number of Sediment Bed Layers and Number of Sediments and set up the General tab as seen in Figure 26.

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

6. Model Timing

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.

7. Running EFDC

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.

(info)  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.