The following are typical problems encountered with 3D mesh types.
Topics in this section
High aspect ratio (3D)
Aspect ratio refers to the relationship between width and height of a mesh element. When the aspect ratio is too high, the tetrahedron (tetra) may be flat or distorted, which will affect the accuracy of results.
Inverted tetrahedron (tetra)
Incorrect editing of a mesh can result in adjacent tetrahedron (tetra) overlapping. This is called an inverted tetrahedron.
Collapsed surface
An edited mesh might accidently result in a surface node being merged onto the opposite face of the model. This is called a collapsed surface.
Insufficient refinement through the thickness
A tetrahedron that has all four nodes on a surface, distorts calculations in that area. This is called insufficient refinement through the thickness.
Internal long edges
When constructing a 3D mesh, the length of each tetrahedron's edge is compared to the average surface mesh length. If the ratio of an edge exceeds a defined value, the tetrahedron is said to have an internal long edge.
Large volume tetrahedron (tetra)
An homogenous mesh will yield a better analysis. Individual tetrahedron that have a large relative volume can impact on the accuracy of the analysis.
Tetrahedron (tetra) with extreme interfacial angles
Any tetrahedral elements in which the angle between one surface and an adjacent surface is either very close to 0 or 180 degrees is said to be a tetra with extreme angles between faces.