15.2.4 Normals to boundaries

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15.2.4 Normals to boundaries

In Section 10.4, the usage

   b   1   V100 = normal

was used to calculate a boundary unit normal for use in other later boundary computations. This again is a local calculation in each element and discontinuities are not resolved; the treatment is accurate, even at corners. Once again this accuracy is lost if the results are assigned to the global level, with inevitable averaging. The computation of the normal is isoparametric, that is appropriate accuracy is preserved on curved boundaries.