EFDC+ has fully incorporated the Marine Hydrokinetic (MHK) module to simulate placement and potential effects of installation and operation of turbines and wave energy converters in rivers, tidal channels, ocean currents, and other water bodies. The code is implemented based on Sandia National Laboratories modified Environmental Fluid Dynamics Code (SNL-EFDC) (James, 2010).

The MHK module is always displayed under the Modules tab as shown in Figure 1, RMC on the Marine Hydrokinetic Devices sub-module, to display the Marine Hydrokinetic Devices form to set up the MHK devices.

Figure 1 MHK Module.

MHK Devises Settings

MHK Devices – General Tab

In the Marine Hydrokinetics Device form, the General tab is shown in Figure 2, where the user can specify the power extracted from the flow. There are different methods for computing power extracted from flow, though currently only one method is enabled. The method is to use the specified thrust coefficient that is multiplied by velocity cubed. The user may specify the Velocity Source for Power Calculations required for computation of power. The available options are local cell velocity and upstream velocity.

In the MHK Interaction with Flow Field frame, the user must specify coefficients. Guidance on how to determine these definitions can be found in the SNL user guide (James, 2010).

The MHK Output Option frame provides options for text-based reporting of the output. These options include:

Energy fluxes access a transverse section upstream and downstream of the device
Average velocity and the Z-profile for the tidal reference model at the throat
Average velocity and surface velocity for the reference model
Outputs for straight-channel calibration model of the wake structure.

Figure 2 MHK Devices: General tab.

Device Parameters Tab

The Device Parameters tab is shown in Figure 3. Here the user specifies the number of MHK devices in the model by entering a number in the Number of MHK Device Type. To set properties for each individual MHK device, the user can select each one from the Current Device Type drop-down box. The device names can be specified by the user, and for each device, the user must specify the device dimensions and a range of coefficients. If the Use Device Settings checkbox is checked, the MHK will be displayed in the 3D View base on their settings. Guidance on how to determine these definitions can be found in the SNL user guide (James, 2010).

Figure 3 MHK Devices: Device Parameters tab.

Device Locations

The Device Locations tab is where the user should specify the location for the devices. The user can enter I, J index, and Easting, Northing for the cell to specify locations manually. Type or copy and paste the device number which corresponds to that cell as shown in Marine Hydrokinetic Devices#Figure 4. Note that the Device Type column is defined in the Device Parameters tab previously. (e.g 1 or 2,. etc).

In addition, the user can use the Assign button to assign MHK devices to grid cells by clicking that button. The MHK Cell Assignments form will appear as shown in Figure 5, on that form, the user first needs to enter the device type on the box for Default MHK Device Type (e.g. 1). Next, select one of four radial button options as shown in Figure 5.

Assign Values to All Grid Cells: This option will assign the selected device type to all grid cells of the model.

Cell Assignments Using Bounding Polygons in a File: This option will assign the selected device type to grid cells inside the polygon.

Discrete Cells Assignments Using X, Y Pairs in a File: This option will assign the selected device type to grid cells defined by X, Y coordinates.

Discrete Cells Assignments Using I, J Pairs in a File: This option will assign the selected device type to grid cells defined by I, J indices.

In the File Name, click on the Browse button to browse to the file (*.p2d). The Overwrite Current Cell Values checkbox can be used to overwrite the old assignment. If the checkbox is not checked, the next assignment will append to the old assignment. Finally, click on the Apply button to proceed with assignments. A message will pop up as shown in Figure 6. Click the OK button to finish the MHK devices to grid cells. the values of I, J, Easting, Northing, and Device Type columns will be updated for the Location of Grid Cells with MHK Devices frame.

Figure 4 MHK Devices: Device Location tab.

Figure 5 Device Location tab: MHK Cell Assignments.

Figure 6 Successful MHK Assignments.

Visualization Tab

The Visualization tab allows the setting of the linkage from the COLLADA files (*.dae) 3D object of the MHK devices to view in the 3D View as shown in Figure 7. Click on the Settings button on that form to set scale, rotation, and color for the 3D object as shown in Figure 8. Check on the box of The Change Object Color it allows changing the color for the object by selecting the color from the Object Color option, otherwise the color of the object will use the original color from the COLLADA files.

Figure 7 MHK Devices: Visualization tab.

Figure 8 3D Object Settings.

MHK Devices in 2DH View

To display the MHK devices in the 2DH View, click Add New Model Layer from the Layer Control. The 2DH View form will display, the user selects Hydrodynamics for Primary Group and MHK for Parameter from the drop-down list as shown in Figure 9 then click Add button. The MHK layer will be added to the Layer Control. Some options will pop up as Properties, Zoom to Layer, Edit and Remove from right click on that layer as shown in Figure 10. The user can select Properties option to change the color and size of the MHK symbol as shown in Figure 11. EE set default symbol for MHK is the solid triangle.

Figure 9 Add MHK in 2DH View.

Figure 10 Right click options of MHK layer.

Figure 11 MHK layer properties.

MHK Devices in 3D View

To display the MHK devices in the 3D View, click Add New Model Layer from the Layer Control. The 3D View Option form will display, the user selects Hydrodynamics for Primary Group and MHK for Parameter from the drop-down list as shown in Figure 12 then click Add button.

Figure 12 Add MHK in 3D View.

The user also can load the MHK object into the 3D View by using Import External Layer button from the Layer Control then browse to the MHK Collada file then click Open button as shown in Figure 13. The MHK object (e.g turbine) will be added to the Layer Control, however, we can not see the object due to its location is not set yet. To set location and other settings for the object, RMC on the turbine layer then select Properties option, the 3D Object Settings form will appear. From that form, the user needs to enter X, Y, Z for the Position frame, scale, and rotation in X, Y, Z direction in Scale and Rotation frame if it is necessary as shown in Figure 14. The object's color can be changed by using the Change Object Color check-box option. Finally, click View button to see the display of the object as shown in Figure 15.

Figure 13 Import external MHK object in 3D View.

Figure 14 3D object settings.

Figure 15 3D object display.