Defining the Motion of the Fluid around the Propeller

The fluid region around the propeller is morphed according to the calculated 6-DOF rigid motion, the prescribed rotation of the propeller, and the non-rigid deformations of the propeller computed by the Solid Stress solver.

To define the motion of the fluid region around the solid propeller:
  1. Right-click the Tools > Motions node and select New > DFBI Morphing.
    With this motion, the fluid region around the propeller is morphed based on the displacements of the contacting solid boundaries.
  2. Select the Motions > DFBI Morphing node and set Morpher Method to BSpline.
At the fluid-structure interface, the fluid boundary deforms based on the total displacement, which has a rigid component (6-DOF and rotation) and a non-rigid component (deformation). For these cases, you can activate the Linear Fitter. When computing the displacement interpolation field, the morpher algorithm considers only the deformations, whereas the rigid displacements are calculated by the linear fitter and added to all mesh vertices.
  1. Select the DFBI Morphing > BSpline Parameters node and activate Linear Fitter.
  2. Select the Regions > Fluid (Propeller) > Physics Values > Motion Specification node and set Motion to DFBI Morphing.
To account for the rotation motion of the solid propeller, apply the same rotation motion to the fluid boundaries:
  1. Expand the Regions > Fluid (Propeller) > Boundaries node.
  2. Multi-select all boundaries, right-click and select Edit.
  3. In the Multiple Objects dialog:
    1. Expand the Physics Conditions > Six DOF Morpher Specification node and set Method to Six Dof Body.
    2. Expand the Physics Values > Morpher Rigid Boundary Motion node and set Rigid Motion to BoatWithPropeller-Motion > Rotation.
    3. Click Close.
To account for the solid deformations at the fluid-structure interface:
  1. Select the Fluid (Propeller) > Boundaries > Fluid (Propeller)/Propeller [0] > Physics Conditions > DeformationSpecification node.
    The default setting, Solid Stress, instructs the morpher to account for the solid deformations computed by the Solid Stress solver.
The main fluid region, Fluid (Boat), contains a fluid boundary in contact with the propeller hub. To account for the rotation of the propeller at this fluid boundary, you use the reference frame associated with the Rotation motion:
  1. Expand the Regions > Fluid (Boat) > Boundaries > PropellerHub node and set the following properties:
    Node Property Setting
    Physics Conditions > Reference Frame Specification Option Local Reference Frame
    Physics Values > Boundary Reference Frame Specification Reference Frame ReferenceFrame for Rotation
  2. Save the simulation.