Dear Franco, > My question here is this: why am I not using the normal to the face? >
To really understand this you need to become more familiar how you arrive at the weak form of the govening equations that you're trying to implement. On the Neumann boundary you are prescribing a traction *vector* (this is the most general case; this vector need not have any particular orientation wrt. the face)/ Using Cauchy's theorem the traction vector can also be expressed as the contraction of a stress tensor and the (outwards) normal vector (see, for example, equ 5.14 in these notes <http://www.maths.manchester.ac.uk/~mheil/Lectures/Elasticity/Material/Chapter5.pdf>). If you are to apply a hydrostatic pressure then this tensor can also be written as a scalar (the pressure) multiplied by the identity tensor - so this case simplifies to a scalar pressure multiplied by the normal vector. So, to reinforce what Luca has already said, it depends on exactly what you're trying to do as to how you'd implement this (and whether or not you need the normal vector at all). Best, Jean-Paul -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
