Checking Mesh Distortion Levels

Simcenter STAR-CCM+ provides a series of field functions that allow you to visualize the distance by which one part-surface description deviates from an earlier description of the same part-surface. This deviation distance is the physical distance between the two triangulated surfaces.

You set the reference part-surface in the field function that corresponds to the description you require, and set the comparison part-surface in a scalar scene that plots the function. The scalar scene must be set to use a later description than the one used by the field function you are plotting.

As an example, consider the tessellated surface for the root description of a part:

After remeshing in an Automated Mesh operation, a further description, Automated Mesh.Remesh, exists for the part surface:

By choosing this part surface in the DeviationDistance.Root field function, and plotting the field function in a scene that shows the Automated Mesh.Remesh description for the part surface, you can observe the deviation between the surfaces:

You can also calculate the deviation distance between different parts, for example the distance between two disjointed parts.

The following deviation distance field functions are available:

DeviationDistance.Root: Generated when geometry parts are imported or created. For the chosen part-surface, compares the description displayed in the scalar scene to the Root description.
DeviationDistance.Imprint: Generated when an Imprint operation is added to the meshing pipeline. For the chosen part-surface, this function compares the description displayed in the scalar scene to the Imprint description.
DeviationDistance.SurfaceWrapper: Generated for a Surface Wrapper operation that has Per-Part Meshing activated. Compares the description in the scalar scene to the Surface Wrapper.Wrap description.
DeviationDistance.AutomatedMesh: Generated when an Automated Mesh operation is added to the meshing pipeline. For the chosen part-surface, compares the description displayed in the scalar scene to the AutomatedMesh.Remesh description.

Before attempting to visualize the deviation distance between two triangulated surfaces, make sure that you have executed the relevant operations to create the description that you are assessing. Although deviation distance can be displayed on any description of the mesh, only one distance is computed per triangle.

To visualize the deviation distance on a surface:

Expand the Automation > Field Functions node, select the deviation distance field function corresponding to the datum description, and set the Parts property to the part surface you are working with.
Choose what parts/descriptions are used in the deviation distance calculation:
- To calculate the distance between different descriptions of the same part, activate the Only Compare Same Parts option. This option is activated by default and is useful for comparing how closely a remeshed surface matches the original input surface.
- To calculate the distance between disjointed parts, deactivate the Only Compare Same Parts option. Deactivating this option is useful for calculating the distance between multiple parts in the scene.

Create a scalar scene which contains the same part surface as the deviation distance field function.

Note	The surface description chosen for the scalar scene must occur later in the pipeline than the description associated with the particular deviation field function you are using. Otherwise, no deviation distance is displayed.

For the scalar displayer of the scene, set the Scalar Field > Function to the particular Deviation Distance function that you require.
The part in the scalar scene updates to display the level of mesh distortion on the triangulated surface.

Note You cannot delete descriptions manually—they are updated after related parts or operations are deleted.