Guidelines and Recommended Practices

Criteria File

  • When defining the Target element size, it is recommended to use either the Minimal height or the Minimal normalized height methods. These methods do not affect the quality of quads, and for the same mesh only the tria quality will be reduced with the minimum height method. Moreover, the use of the Shortest edge method may result in the creation of rhombus-like quads, which are only useful for special kinds of meshes.
  • After the Target element size, the most important aspects are the Min Size and Max Size. These have the highest impact on the final mesh output.
    • The Min Size should not be too big with respect to the Target element size. The recommended size is 33% of the Target element size. On the upper end, a value of 40%-50% of the Target element size is also acceptable. A larger than recommended Min Size may trigger intensive cleanup that disrupts the mesh flow.
    • The Max Size should not be too small. A value of 175% of the Target element size is reasonable.
    • The range between Min Size and Max Size should not be too tight, otherwise there is limited ability to improve the mesh result.
  • A Warpage value between 20°-25° is recommended. A value of 15° may be too tight, over constraining the mesh generation. With a value of 15° or lower, violating quads may have some nodes be moved away from the geometry, or may be split into two trias, depending on the parameter file settings.
  • Skew, Min Angle, and Max Angle are dependent on each other. The Jacobian value also has an effect on the element shape. An element with a small Jacobian value, for example, will have poor angles. Calculating the Jacobian at the corner points is a more strict setting.
  • Taper is used for orthogonality. In some way, it controls the same outcome that angles and Jacobian also account for. Taper is most useful for solvers that have a direct requirement for it.
  • The reduction of tria elements is performed automatically by the BatchMesher, even when the criterion % of Trias is not enabled. Therefore, you will not see a large difference when changing this value with respect to the default BatchMesher result.
  • Careful consideration should always be given when changing criteria values. As many criteria are interdependent, over-constrained values can lead to poor mesh flow and mesh adherence to the geometry is likely to be disturbed.