Understanding the Sweepable Body check

You can use the Check for Sweepable Body option in the Simulation Settings group to have the software temporarily change the color of selected solid bodies to indicate whether they are likely sweepable with the Multi Body-Infer Target method in the 3D Swept Mesh dialog box. While you are using the Split Body dialog box, the temporary colors update automatically as you divide the geometry.

Determining the possible source and target faces

For each body, the software first evaluates the topology to determine the possible source and target faces.

• Faces that have the greatest number of loops are considered possible source faces. If all faces in the body are comprised of a single loop, the software considers all faces as possible source faces.

• For each possible source face:Any attached face is considered to be a wall face.All other faces are considered to be possible target faces.

• Among the possible target faces, only faces that are comprised of the same number of loops as the possible source face are considered to be valid target faces.

Evaluating wall faces

For each source face, the software now has a list of valid target faces. The software then evaluates the possible wall faces for each source-target pair. Wall faces must meet the following requirements:

• Wall faces should be comprised of more than a single loop.

• Wall faces should have more than 3 edges.

If a wall faces meets those requirements, the software then performs additional checks to determine the overall quality of the wall face.

• The normal of the wall face at its centroid should not be parallel to the normal of either the source or target face within a 30° angle.

• The wall face should have four corners. Any vertex at which the angle is greater than 15° and less than 165° is considered a corner.The software continues to evaluate the wall faces until it finds a source and target pair that has wall faces that are all categorized as good.

For each of these criteria:

• Wall faces that meet this criteria are categorized as good.

• Wall faces that meet this criteria are categorized as adequate.

Assigning colors to the body

Color	Meaning
Green	Green indicates that there is a high likelihood that the software can generate a hexahedral mesh on the body without any additional partitions.This means that for a selected body, the software can find at least one pair of source and target faces where the associated wall faces:Are comprised of a single loop with at least three edges.Are not parallel to either the source or target faces within 30°.Have four corners.
Yellow	Yellow indicates that the software may or may not be able to generate a hexahedral mesh on the body without any additional partitions.This means that for a selected body the software can find at least one pair of source and target faces where the associated wall faces are comprised of a single loop with at least three edges but where:Some of the wall faces are parallel to either the source or target faces within 30°.Some of the all faces to not have four corners.
Red	Red indicates that the software cannot generate a hexahedral mesh on the body without additional partitions. Some reasons for this include:The existence of a void in the body.Wall faces are comprised of multiple loops.Given any face on the body, the software cannot automatically determine an appropriate target face.Note: The software also colors a body red if it contains more than 100 faces. The software does not evaluate bodies with more than 100 faces for whether they are sweepable because of the

You can:

• Select the Set Body Color check box in the Split Body dialog box to apply these colors to the associated polygon bodies in the FEM file.

• Use the Sweepable Body customer defaults to customize the colors these colors. In the Customer Defaults dialog box, select Modeling→General→Simulation tab.

Limitations

There are cases in which the software cannot properly determine the meshability of a body based on its topology. In these cases, the software may color a body green though the body may not be meshable with the 3D Swept Mesh command. Some examples of this include bodies in which:

• The source and target faces are so drastically different in topology that sweeping a mesh would result in highly skewed elements. Meshing would fail on this type of body due to the mesh quality.

• The wall faces might be comprised of a single loop but the curves of that loop might meet such that a hole exists in the body.

• The wall faces might not be mapped meshable. There is no simple topological check that the software can perform to determine whether you could generate a mapped mesh on a wall face.

These types of conditions are not easy to detect through a topology check.

Learn more

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Understanding the Sweepable Body check, Simcenter 3D 2021.1 Series

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