Setting Up the Body Force Propeller Method

The setup of the virtual disk of the body force propeller method does not require you to create a separate region in which the model is applied. You create the shape of the virtual disk by specifying the relevant parameters such as radius, thickness, and orientation to an existing mesh. To verify the dimensions and orientation of the virtual disk, you can visualize it by using virtual disk specific field functions.

Refine the mesh in the zone where the virtual disk is to be located. For more information see Observing Virtual Disk Meshing Requirements for the Body Force Propeller Method.

To set up the body force propeller method, choose each child node in turn and set the properties required.

Generally, the propeller performance is available from experiment in terms of thrust coefficient $K t$ , torque coefficient $K q$ , and propeller efficiency $η_{0}$ (given as Eta in the GUI) as a function of advance ratio $J$ . (See Eqns. Eqn. (4981), Eqn. (4982), Eqn. (4983) for a definition of these values). You can specify this data using either a polynomial or table.

To specify the propeller performance curve:
1. If you are using a table to specify the performance curve, import the table within the Tools > Table node, see Table Tasks.
2. Select the Virtual Disk > Propeller Curve node and set the Method to either Polynomial (J) or Table (J).
3. Select the corresponding child node and set its properties.

To create propulsion, for the body force propeller method, thrust and torque vary in the radial direction but not in the azimuthal direction. To specify the radial force distribution you can either use the built in Goldstein optimum distribution or use your own. To specify the radial thrust and torque distribution:

Select the Virtual Disk > Radial Distribution Option and set the Thrust and Torque Distribution. You can either use the same distribution for both thrust and torque, or chose different distributions.
Depending on the Thrust and Torque Distribution selected set the properties within the corresponding Thrust and Torque Specification node and sub-nodes or (Thrust Specification and Torque Specification nodes and sub-nodes if Different Distribution is selected). See Thrust and Torque Specification Properties.

The body force propeller method requires you to set the inflow specification of the virtual disk.

Select the Virtual Disk > Inflow Specification node and set Method.
To find the appropriate inflow method, refer to Setting the Inflow Specification.
Set the properties of the corresponding sub-nodes. For more information on the available settings, see Inflow Specification for Body Force Propeller Method.

Propellers are classified in terms of handedness — they can either be right-handed or left-handed. The handedness of a propeller relates to the direction of rotation of the propeller relative to the direction of thrust of the vessel. For more detailed information, see Propeller Handedness. To specify the propeller handedness:

Select the Virtual Disk > Propeller Handedness Option and set Option to Right Handed or Left Handed.

The operation point defines where on the specified propeller performance curve you want to perform the simulation.

To specify the operation point:
1. Select the Virtual Disk > Operation Point Input Option node and set Option to one of the following choices:
  - Rotation Rate (n)
  - Thrust (T)
  - Torque (Q)
2. Select the corresponding child node and set its properties.
  For more information see Body Force Propeller Reference.