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plot value of dot(n, grad(u)) over boundary

+17 votes

Given a function u over some bounded domain, is there a way to plot dot(n, grad(u)) over the boundary? (Maybe as a FacetFunction.)

asked Aug 19, 2014 by nschloe FEniCS User (7,120 points)

It is easy to plot this function when $\mathbf{n}$ is known and you can form it without using the built-in FacetNormal(). It would be handy to have a way to form $\mathbf{n}$ for use with cell integrals. The interior could just be set to zero.

Is there a simple solution by now?

1 Answer

+2 votes

This does not quite answer your question, but hopefully is useful.

A solution on computing dot(t, grad(u)) has been posted here: How to compute tangential gradient, where t is the tangent along the boundary.

answered Dec 12, 2014 by xpq FEniCS Novice (660 points)
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