Defining the Motion of the Overset Region

In this simulation, the background fluid remains static while the overset region moves according to the wing displacements. To define the motion of the overset region, you apply the motion-managed coordinate system to the region and morpher-controlled deformation to the fluid-structure interface.

To define the morphing motion for the fluid-structure interface:

Right-click the Tools > Motions node and select New > Morphing.
Rename the Motions > Morphing node to Overset Morphing.
Select the Overset Morphing node and set Morpher Method to RBF.

At the fluid-structure interface, the fluid boundary must deform based on the total wing displacement, which has a rigid component (prescribed motion) and a non-rigid component (deformation). For these cases, Simcenter STAR-CCM+ provides the Linear Fitter, which deduces the linear transformation that produces the rigid displacements. When computing the displacement interpolation field, the morpher algorithm considers only the deformations, whereas the rigid displacements calculated by the linear fitter are simply added to all mesh vertices.

Select the Overset Morphing > RBF Parameters node and activate Linear Fitter.

Apply the morpher to the overset region:

Select the Regions > Overset Domain > Physics Values > Motion Specification node and set Motion to Overset Morphing.
Simcenter STAR-CCM+ automatically sets the morpher settings on the interface between the wing and the overset region. That is, the Morpher Displacement Specification for the Fluid/Structure [1] overset boundary is set to Solid Stress, which specifies that the morpher moves the boundary based on the displacement of the contacting solid wing.
Select the Overset Domain > Boundaries > Overset > Physics Conditions > Morpher Specification node and set Specification to Floating.
With the floating method, mesh vertices on the boundary move in response to the interpolation field created by the morpher.

Use the same morpher specification for the mount boundary:

Select the Overset Domain > Boundaries > Mount > Physics Conditions > Morpher Specification node and set Specification to Floating.

Adjust the mesh morpher solver settings:

Select the Solvers > Mesh Morpher node and activate Morph from Zero.
This setting is useful for periodic motions. At each time-step, the mesh morpher applies the interpolated displacements to the initial mesh configuration rather than the mesh configuration at the previous time-step, preventing the incremental accumulation of distortions.

Finally, define the overset topology with respect to the coordinate system that follows the sweeping motion. In this tutorial, the overset boundary does not completely enclose the overset region. To correctly define the overset topology, you specify the direction in which the overset boundary appears to be closed:

Select the Regions > Overset Domain > Physics Conditions > Overset Topology node and set Option to Direction.
Select the Overset Domain > Physics Values > Overset Direction Specification node and set Coordinate System to Laboratory > Stroke Plane > Wing Pitching-CSys.
By default, the overset direction is set to be along the positive X axis of the specified coordinate system. This is appropriate for this case.
Save the simulation.