Singularities in adaptive meshing

A singularity represents infinite stresses that occur at singular points, sharp corners, geometric discontinuities, or at the location of point-based or concentrated loads or constraints. Because singularities are points of high error, they can influence the refinement of the entire mesh. When a singularity occurs, the software needs to infinitely refine the mesh for the solution to converge.

You can remove singularities during adaptive meshing in two ways:

• To have the software automatically detect and remove singularities that can occur at geometric locations or at locations where point-based loads or constraints are applied, select the Automatically Detect Singularities option in the Adaptive Meta Solution dialog box.

• To explicitly specify regions in your model where you believe a singularity may occur, create a Singularity Zone type of adaptivity zone.

In an adaptivity solution process, you can use either or both of these singularity detection techniques. If the software detects a singularity, it prevents extremely fine mesh refinement. Instead, the software tries to adequately refine the mesh the region around a singularity to satisfy the specified error criteria.

Adaptive mesh results with singularity detection turned off.	Adaptive mesh results with singularity detection turned on.

The software lists singularity information in the log file and creates a group that contains the nodes at the site of the singularity in the Simulation Navigator.

Detecting singularities automatically

Select the Detect Singularities Automatically check box in the Adaptive Meta Solution dialog box to have the software detect singularities that occur:

• At locations where edge- and point-based constraints are applied.

• At locations where point-based loads, such as a force on a node, are applied.

• At vertices that connect edges that are not tangent-continuous, as well as those along the edges themselves.

The software limits the refinement of elements that lie within a certain radius of a singularity. Typically, the software refines no more than four elements within the specified radius of a singularity.

You can either specify a radius of singularity or have the software automatically calculate one for you. The software uses the following calculation to compute a singularity radius:

Singularity Radius = 0.01(area of all sheet bodies)1/2 + (volume of all solid bodies)1/3

Creating singularity zones

Use the Singularity Zone option in the Adaptivity Zone dialog box to specify regions within your model where you believe a singularity is likely to occur. You can select the following

• Vertex

• Mesh point

• Polygon edge (for singularities in 3D meshes)

The Simulation Navigator stores Singularity Zone items under the Zones folder in each adaptivity solution process node.

Where do I find it?

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed partSimcenter Nastran, MSC Nastran, Simcenter 3D Multiphysics, Simcenter 3D Thermal, Abaqus, or ANSYS as the specified solver
Simulation Navigator	In the appropriate Adaptivity solution process node, right-click the Zones folder→New

Learn more

Adaptive meshing

Adaptive meshing workflow

Supported solution types for adaptive meshing

Pre-processing requirements for adaptive meshing

Specifying accuracy parameters for adaptive meshing

Specifying the mesh parameters for adaptive meshing

Understanding the adaptive refinement process

Excluding parts of the model from adaptive meshing

Refining specific parts of an adaptive mesh

Viewing adaptive meshing results

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Singularities in adaptive meshing, Simcenter 3D 2021.1 Series

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