# Relative Anisotropic Mesh Size

This option allows you to enter a relative size and a tensor that defines the orientation of the anisotropy.

Note that the tensor must define three orthogonal vectors. The size is evaluated by multiplying the relative size of each volume region in the group by the orientation tensor, then multiplying by the length of the longest edge of the bounding box that completely encloses the volume to determine the final size used by the mesher. The mesher has a practical limit on anisotropy of approximately 5:1. Requests for higher levels of anisotropy in unstructured mesh regions will most likely not be satisfied.