Improving a FEM Mesh—Topology Optimization

After the mesh generator creates a mesh, it attempts to improve the quality of the elements by performing two element optimization passes. During these passes, the system examines the aspect ratio of each element to determine whether the element is well shaped so that it can be easily handled by the solver. The system also checks the elements to ensure that they comply with all element quality measures.

If the system determines that some of the elements are poorly shaped, it attempts to improve the elements by:

• Smoothing—the system adjusts the position of the nodes to improve element shape. During this process, the software does not introduce new nodes or elements, move nodes at hard points or vertices, or move nodes on edges, surfaces, or hard curves away from the edge, surface, or hard curve.

• Reconfiguring edges—For triangular elements, the system reconfigures element edges shared by a pair of elements if it determines that a different edge configuration produces a better shape for the two elements. This form of optimization primarily improves triangular shell meshes. However, it can also improve solid tetrahedral meshes because the system develops these meshes by first applying a triangular shell mesh to the model boundary surfaces and then working inward from this initial triangular mesh to create the tetrahedra.

The greatest improvement to the mesh occurs during these two element optimization passes, and, in most cases, you will not need to refine the mesh further. However, if you examine a mesh and think that the mesh still requires adjustment, you can click Home > Mesh > Improve to perform additional optimization passes. As an alternative, you may want to add mesh controls to your model in areas that concern you, and then remesh the model.

When you click Home > Mesh > Improve, the system performs the number of passes that you indicate, and shows a message in the message area indicating the number of passes it has completed. The pass count is cumulative. In other words, if you specify four additional passes, the system will report six passes altogether—two passes that occurred as part of mesh creation plus the four passes you specified. The pass count persists from session to session, incrementing for each improvement pass, until you erase the mesh or create a new mesh.

Be aware that the higher the pass count, the longer the mesher will need to perform the optimization. With each pass, the amount of improvement is also less.