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[Hans Petter Langtangen <hpl@xxxxxxxxx>]

Fri, 18 Jun Anders Logg wrote:
> 3. Is the normal flux + or - grad(u).n? I think of it as -grad(u).n.

For k*inner(grad(u), grad(v))*dx, -k*grad(u).n is the right flux. It has
a minus sign. Some people use the word flux for grad(u).n, but that's
sloppy - normal derivative is then better.

Hans Petter