[petsc-dev] access to finite element second derivatives

[Matthew Knepley]

On Mon, Dec 2, 2013 at 4:02 PM, Geoffrey Irving <irving at naml.us> wrote:

> For simulations of bending shells, I'm going to need access to second
> derivatives of both primal and dual basis functions.  This means
> versions of f0,f1 that take second derivatives, plus f2 for inner
> products with the dual second derivatives.
>
> Have you thought about how to fit this into the current code without
> interfering with speed when the second derivatives aren't required?
> It also increases the relevance of Jed's note that material models and
> material field evaluations might ideally be shared across evaluations
> at the same quadrature point.  I.e., merging f1 and f2 into a single
> call might avoid redundancy.
>
> I haven't used actual shell elements before (all the bending
> simulations I've done used ad-hoc hinge forces), so any advice about
> element choice would be great.  Are the default quadratic elements a
> good choice?
>

So these elements are C1? I would have a tendency to fall back on mixed
formulations or interior penalty (I don't understand these) formulations for
this. Then C0 elements are alright.

Jed, have you used any of these?

   Matt


> Thanks,
> Geoffrey
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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