Morpher Boundary Condition Reference

Morpher Specification

Controls how the morphing for a boundary is performed. Activated when the Morpher motion is selected.

Specification

Corresponding Morpher Physics Value Nodes

Fixed

The vertices of the boundary are fixed in space.

The Fixed morpher boundary method supplies control points for use in calculating the interpolation field. In this case, however, the displacement that is associated with the control points is zero.

Morpher Thinout Factor (RBF only)

Reduces the number of control points in order to reduce computational costs. The Vertex Thinout Factor specifies the fraction of boundary vertices that are used as control points. Vertices that are not chosen are given the applied boundary condition to ensure correct boundary movement.

For non-planar boundaries that are close to the zone of influence, keep the Vertex Thin Factor close to 1.0 to avoid distortion of the Fixed boundary.

For planar boundaries located far enough from the zone of influence, reduce the Vertex Thinout Factor (in the example shown, a value of 0.1 is used for the funnel section).

Rigid Prism Layer Morphing

The rigid prism layer method preserves the original undeformed shape of the prism layers adjacent to the boundary.

However, when the distance between the boundary and another boundary approaching it becomes too small, the prism layer cells are deformed. You set this threshold distance using the Minimum Gap To Another Boundary.

For a Fixed boundary, when this option is active, the vertices in the prism layers stay fixed. The deformation coming from the morpher is distributed throughout the remaining cell vertices .

Displacement

The boundary vertices are moved by a specified distance. There are several types of displacement types available. Adds the Morpher Displacement Specification node, from which you can select further options for displacing the boundary vertices.

Note	For simulation cases with solid and fluid regions that are in contact, and where morphing motion is specified within the fluid or solid regions, `Morpher Specification` is automatically set to Displacement on the Contact Interface boundaries.

Depends on options chosen under the Morpher Displacement Specification node.

Rigid Prism Layer Morphing

The rigid prism layer method preserves the original undeformed shape of the prism layers adjacent to the boundary.

For a Displacement boundary, when this option is active, the vertices in the prism layers follow the boundary motion only but are not deformed.

Note

If the Rigid Prism Layer Morphing option is enabled for a Displacement boundary, the morpher first checks the rigidness of the boundary—whether the boundary's displacement is only due to the translation and rotation applied. In case of a non-rigid boundary (e.g due to solid stress deformation), the active Rigid Prism Layer Morphing option is then ignored by the morpher solver.

Floating

Vertices on the boundary move according to the interpolation of the displacement vector field.

With the floating method, mesh vertices on the boundary move in response to the interpolation field created by the morpher. An example of where this morpher boundary type could be used is for the side walls of a piston undergoing one-dimensional expansion or contraction, as shown in the illustration below.

None.

Constraint: Boundary vertices are constrained to stay within a plane or a triangulated surface. Adds the Morpher Plane Constraint Specification node, from which you can select whether to activate Use Triangulation Plane option.

Depends on options chosen under the Morpher Constraint Specification node.

Note	Constraint is used for all Symmetry boundaries.

For the specific settings available with the DFBI Morphing motion, see Six DOF Morpher Specification.

Morpher Displacement Specification

Controls which type of displacement is used to morph the boundary vertices.

Specification	Corresponding Morpher Physics Value Nodes
Total Linear total displacement per time-step of boundary vertices relative to the initial position of the boundary vertices. The target coordinates at each time-step are: `target_coordinate = reference_coordinate + total_displacement` Where `reference_coordinate` indicates either the initial position with respect to the first mesh configuration (`initial_coordinate`), or the initial position with respect to the mesh configuration from the last remesh event (`saved_coordinate`). These reference configurations are equivalent if you do not remesh the geometry. If you apply a rigid motion, the target coordinates also include the rigid displacement with respect to the initial position, due to the applied motion.	Morpher Total Linear Displacement Specified as a vector profile with respect to Coordinate System. Morpher Rigid Boundary Motion Allows you to combine the incremental linear displacement morphing motion of this boundary with a rigid motion. All types of rigid motions are compatible. Selects the Rigid Motion that you define under Tools > Motion. Morpher Thinout Factor (RBF only) Reduces the number of vertices that are used as control points in order to reduce computational costs. Specifies the Vertex Thin Factor to use only this fraction of boundary vertices as control vertices. Vertices that are not chosen are given the applied boundary condition (so that the boundary movement is correct). Total Displacement Reference Specifies the reference initial position for the boundary vertices. Initial Coords—initial coordinates with respect to the very first mesh configuration (stored in `initial_coordinate` field function). Saved Coords—initial coordinates with respect to the last remeshed configuration (stored in `saved_coordinate` field function). Without remeshing, these options are equivalent and provide the same coordinates.
Incremental Linear displacement of boundary vertices relative to the vertex positions of the previous time-step or iteration. The boundary target vertex coordinates are computed as: `target_coordinate = current_coordinate + incremental_displacement`. In the case that an additional Rigid Boundary Motion is applied: `target_coordinate = current_transform(current_coordinate)+ incremental_displacement` `current_transform` is the the current motion transformation from the applied Rigid Boundary Motion referring to the current position.	Morpher Incremental Linear Displacement Specified as a vector profile with respect to Coordinate System. Morpher Rigid Boundary Motion Allows you to combine the incremental linear displacement morphing motion of this boundary with a rigid motion. All types of rigid motions are compatible. Selects the Rigid Motion that you define under Tools > Motion. Morpher Thinout Factor (RBF only) See under Total Displacement specification
Grid Velocity Vertices on this boundary are moved using the specified velocity. The resulting displacement is proportional to the time step used for the simulation. The boundary target vertex coordinates are computed as: `target_coordinate = current_coordinate + grid_velocity * time_step`. The option to set the Displacement using grid velocity is only available if the solution is set to unsteady using the appropriate unsteady model for Time under the [physics continuum] node.	Grid Velocity Input as a vector profile. If a user-defined profile is used to set this value, the profile must be of type Region, rather than type Boundary. In this instance, however, only the boundary vertices are used. Morpher Thinout Factor (RBF only) See under Total Displacement specification
Internal The displacement field is computed internally by other Simcenter STAR-CCM+ models and is treated as an incremental displacement. This method is used by the Fluid Film Solidification model (for example for wing de-icing simulations) and the Viscous Flow model for modeling free-surface tracking (for example for extrusion simulations) or inverse die design simulations. Adds the Adaptive Die Option node.	None.
Coordinate Offset Specifies an incremental displacement with respect to any type of coordinate system, for example, a cylindrical coordinate system. For more information, see What is the Coordinate Offset.	Coordinate Offset You specify the coordinate offset value as a vector profile with respect to Coordinate System. Morpher Thinout Factor (RBF only) See under Total Constraint specification
Solid Stress This `Morpher Displacement Specification` applies only to simulations that have the Solid Stress model selected and only to the Contact Interfaces between the solid and fluid regions. The Solid Stress model computes a vector displacement field, which is mapped from faces to vertices and applied as an incremental displacement.	Displacement Specifies the displacement Method to apply the solid displacement computed by Solid Stress solver. The only option is Mapped Displacement. Morpher Thinout Factor (RBF only) See under Total Displacement specification
Tangential To Surface Vertices on this surface are moved tangential to the surface. The resulting displacement is proportional to the time-step that is used for the simulation. For accuracy, the surface must be flat, or nearly so. The boundary target vertex coordinates are computed as: `target_coordinate = current_coordinate + incremental_displacement`. The vector pointing from `current_coordinate` to `target_coordinate` is then corrected so that the distances `current_coordinate to surface` and `target_coordinate to surface` are equal.	Morpher Incremental Linear Displacement Specified as a vector profile with respect to Coordinate System. Displacements must be tangential to the selected surface. Morpher Rigid Boundary Motion Allows you to combine the incremental linear displacement morphing motion of this boundary with a rigid motion. All types of rigid motions are compatible, if they remain tangential to the selected surface. Selects the Rigid Motion that you define under Tools > Motion. Morpher Thinout Factor (RBF only) See under Total Constraint specification Part Surface You select the surface of a geometry part to act as a constraint. The geometry part can originate from the following sources: Conversion of 3D-CAD bodies Imported surfaces Creation of shape geometries within Simcenter STAR-CCM+ Results of mesh operations

Morpher Constraint Specification

Specifies the type of constraint that is applied to the boundary when the Morpher Specification node is set to Constraint. The following table lists the constraints and the corresponding Physics Value nodes. In all but one case (Part Surface), there are no related Physics Value nodes for the BSpline morpher.

Constraint	Corresponding Physics Value Nodes
Boundary Plane The boundary vertices can move only within the plane of the boundary, which is an infinite plane whose equation is defined using a least-square fitting method. This behavior is appropriate for simulations similar to the one shown below: Adds the Morpher Plane Constraint Specification node, which allows you to activate Use Triangulated Plane option. If the Use Triangulated Plane is activated, the plane is then triangulated.	RBF Morpher Morpher Plane Options Determines the morpher behaviour for points near this plane. Starting at a distance that you specify as Damping Factor, the displacements at the boundary are damped smoothly to zero. The Damping Factor corresponds to $L_{p}$ in Eqn. (4857). The default value of 0.0 means that the distances are calculated automatically. The Continuity Level specifies which damping function to use in smoothing vertex displacements approaching the plane. For more information, see Boundary Plane Conditions (RBF Morpher). The Ignore Factor is multiplied by the Damping Factor to calculate a finite distance. Control points closer than the specified distance to this plane are given special treatment. A value of zero is acceptable. BSpline Morpher None.
Fixed Boundary Plane Mesh vertices lying on a Fixed Boundary Plane are not moved in response to the morpher interpolation field. This boundary differs from the Fixed boundary in that no control points are taken from the boundary this method is applied to. Ultimately this means that a more computationally efficient approach can be taken. Note, however, that applying this boundary condition results in the creation of an infinite plane that could potentially intersect other parts of the model geometry. The outlet of the funnel section below would be a suitable boundary on which to apply the Fixed Plane method:	Same as for the Boundary Plane constraint
Initial Boundary The boundary vertices slide along the original boundary vertices at time zero. These act as a guide surface, which can be of any reasonable shape (as shown below).	None.
Part Surface The boundary vertices slide along a part surface that is used as a guide surface that can have any reasonable position and shape. The part surface can already exist as a feature of the model, or it can be produced for the purposes of providing a guide surface. The part does not have to coincide with the original region geometry—as shown in the image below, where the mesh is projected onto the part surfaces (in green) after initialization. To ensure consistent morphing at the edges, make sure that the constraint surfaces intersect. When using Boundary Plane and Part Surface, make sure the calculated infinite plane intersects with the Part Surface. For example, you can extend the Part Surface in the normal direction of the Boundary Plane to guarantee this intersection. See also: Consistent Morphing for Edges.	Morpher Rigid Boundary Motion Allows you to combine the Part Surface constrained morphing motion of this boundary with a rigid body motion. All types of rigid body motions are compatible. Select the Rigid Motion that you define under Tools > Motion. Part Surface You select the surface of a geometry part to act as a constraint. The geometry part can originate from the following sources: Conversion of 3D-CAD bodies Imported surfaces Creation of shape geometries within Simcenter STAR-CCM+ Results of mesh operations

Morpher Plane Constraint Specification

Defines a plane for constrained boundary vertices to slide on. Simcenter STAR-CCM+ implements two methods for defining the plane:

by using the equation of the plane
by triangulating the plane

Additional options for damping at these planes are only relevant for the RBF morphing method.

Use Triangulated Plane	Corresponding Value Nodes
When Activated, the plane is defined by finding an equation of the plane for the boundary using a least-square fitting method. The plane is then triangulated. The following steps are performed: The displacement is calculated and all vertices are morphed. The vertices on the boundary are also displaced and treated as floating. The displaced boundary vertices are projected back onto the closest triangle of the boundary plane. The whole region is morphed one more time, but now the sliding boundary is treated as a displacement boundary that uses the projected coordinates as target coordinates. These steps are performed inside Simcenter STAR-CCM+ and you observe only the final result. This procedure is more accurate than using the non-triangulating approach (Use Triangulated Plane deactivated), but it is computationally more expensive. The boundary plane can be moved additionally by a rigid body motion.	Morpher Rigid Boundary Motion Allows you to combine the Triangulated Plane constrained morphing motion of this boundary with a rigid motion. All types of rigid motions are compatible. Selects the Rigid Motion that you define under Tools > Motion.
When Deactivated, an infinite plane is defined by finding an equation of the plane for the boundary using a least-square fitting method. For constraining the boundary vertices to the boundary plane, the following steps are performed inside Simcenter STAR-CCM+: The displacement is calculated and all vertices are morphed. The normal component of the displacement is damped. The damping magnitude is related to the distance of the vertices to the boundary plane. The closer the vertices are to the boundary plane, the higher the damping. At the boundary, the displacement of the vertices is damped to zero. Through this damping, the boundary vertices are projected onto the boundary plane. The damping options can be adjusted for RBF morpher only.	Morpher Plane Options (RBF only) Determines the morpher behaviour for points near this plane. Starting at a distance that you specify as Damping Factor, the displacements at the boundary are damped smoothly to zero. The Damping Factor corresponds to $L_{p}$ in Eqn. (4857). The default value of 0.0 means that the distances are calculated automatically. The Continuity Level specifies which damping function to use in smoothing vertex displacements approaching the plane. For more information, see Boundary Plane Conditions (RBF Morpher). The Ignore Factor is multiplied by the Damping Factor to calculate a finite distance. Control points closer than the specified distance to this plane are given special treatment. A value of zero is acceptable.

Use Triangulated Plane

Corresponding Value Nodes

When Activated, the plane is defined by finding an equation of the plane for the boundary using a least-square fitting method. The plane is then triangulated. The following steps are performed:

The displacement is calculated and all vertices are morphed. The vertices on the boundary are also displaced and treated as floating.
The displaced boundary vertices are projected back onto the closest triangle of the boundary plane.
The whole region is morphed one more time, but now the sliding boundary is treated as a displacement boundary that uses the projected coordinates as target coordinates.

These steps are performed inside Simcenter STAR-CCM+ and you observe only the final result. This procedure is more accurate than using the non-triangulating approach (Use Triangulated Plane deactivated), but it is computationally more expensive.

The boundary plane can be moved additionally by a rigid body motion.

Morpher Rigid Boundary Motion: Allows you to combine the Triangulated Plane constrained morphing motion of this boundary with a rigid motion. All types of rigid motions are compatible. Selects the Rigid Motion that you define under Tools > Motion.

When Deactivated, an infinite plane is defined by finding an equation of the plane for the boundary using a least-square fitting method.

For constraining the boundary vertices to the boundary plane, the following steps are performed inside Simcenter STAR-CCM+:

The displacement is calculated and all vertices are morphed.
The normal component of the displacement is damped. The damping magnitude is related to the distance of the vertices to the boundary plane. The closer the vertices are to the boundary plane, the higher the damping. At the boundary, the displacement of the vertices is damped to zero. Through this damping, the boundary vertices are projected onto the boundary plane.

The damping options can be adjusted for RBF morpher only.

Morpher Plane Options (RBF only)

Determines the morpher behaviour for points near this plane.

Starting at a distance that you specify as Damping Factor, the displacements at the boundary are damped smoothly to zero. The Damping Factor corresponds to $L_{p}$ in Eqn. (4857). The default value of 0.0 means that the distances are calculated automatically.

The Continuity Level specifies which damping function to use in smoothing vertex displacements approaching the plane. For more information, see Boundary Plane Conditions (RBF Morpher).

The Ignore Factor is multiplied by the Damping Factor to calculate a finite distance. Control points closer than the specified distance to this plane are given special treatment. A value of zero is acceptable.

Adaptive Die Option

For a non-Newtonian Inverse Die Simulation. Adapts the shape of the die in response to the geometry and movement of a specified extrudate. Activated when Morpher Specification is set to Displacement. The available options are:

Tapered
Allows the die wall to taper in response to the extrudate flow.
Parallel
Specifies a short section with a higher stiffness factor, giving a transition between the die exit with the Tapered condition and the extrudate with the Free Surface condition.
Fixed
Keeps the wall geometry fixed. This is the default.