Tight wrap creates a wrapped surface mesh which adheres as closely as possible to the
original FE topology representation, automatically detecting and following the surface
features of the model.
The accuracy of the output is dictated by the element size: the larger the element
size the less detail, the smaller the element size the more detail. This algorithm
works differently than the loose wrap in that it projects the nodes of the shrink
wrap to the original mesh, hence it is able to more accurately capture features.
Comparison of Tight and Loose Meshing
Notice the differences between tight and loose meshing, especially in the pulleys on
the front of the engine and the resulting width of the individual cylinder exhaust
pipes.
Comparison of Altering the Jacobian Value for Solid Mesh Generation
Within both tight and loose wrap algorithms there is an option to generate solid
mesh. This will generate an all-hexa mesh on completion of the shrink wrap. When the
generate solid mesh checkbox is active it exposes a
minimum jacobian input; this option essentially hexa meshes the part with this
element quality criteria defined. It controls the hexa quality which is directly
linked to the adherence to the topological features of the original component. The
jacobian value must be between 0 and 1. The nearer the value is to 1 the cruder the
output will appear (the mesh will be more heavily voxelised). When the value is
closer to 0, you allow the shrink wrap solid mesh algorithm to smooth and adhere to
more features while maintaining the solid mesh minimum jacobian element quality. By
default the minimum jacobian value is 0.3.
Shrink Wrapping with Feature Recognition
An additional option can be used to manually define features which will be adhered to
during the meshing process. Typically, when using the shrink wrap the mesh attempts
to follow features, but has some freedom to break away from original edges of the
part. However, when the features are manually selected within the panel the
resultant shrink wrap mesh will follow the chosen features. This can be important
when defining a face of a component that may be in contact with other parts, or
there may just be a feature that needs to be recognized and adhered to and cannot be
approximated for whatever reason.
Comparison of using Global and Local Systems for Mesh Orientation
There is also an advanced option to control the mesh orientation. If you have a
non-uniform part and you want to re-orientate the mesh so that it follows the
features of the original component better then you can use this option. By default
the mesh orientation always adheres to the global system, however, you can generate
a local coordinate system and override the default behavior.
In the example below, you can see the original mesh, the default shrink wrap mesh
using the global system, and the new re-orientated mesh using the local coordinate
system.