Hi Jonathan, I am also looking for the implementation of Hex 20 element in dealii. Did you figure it out how to do that?
Best, Yiliang On Monday, August 5, 2019 at 8:23:35 PM UTC-4 Jonathan Russ wrote: > Professor Bangerth - > > Okay thank you for your advice! I'll take a look at the FE_Poly class as > you suggest. > > Thanks again, > Jonathan > > > On Sun, Aug 4, 2019 at 9:14 PM Wolfgang Bangerth <[email protected]> > wrote: > >> On 8/4/19 5:47 PM, Jonathan Russ wrote: >> > >> > Thank you for your reply. The shape functions of the "quadratic" >> serendipity >> > elements are very similar to the FE_Q(2) elements except they are >> derived >> > without any interior nodes (i.e. in 2D the interior node is removed and >> the >> > shape functions are simple polynomials with 8 undetermined coefficients >> > instead of 9 as with a normal quadratic Lagrange element. Essentially >> the >> > polynomials are not quadratic complete since they are missing the x^2 * >> y^2 >> > term). It's pretty simple to express them in 2D and 3D for the >> "quadratic" >> > case (I put quadratic in quotes since the polynomials are not quadratic >> > complete) but I am more worried about how difficult it would be to get >> this >> > type of element to work with all of the other functionality in dealii >> (e.g. >> > the DoFHandler, Triangulation, grid refinement, etc.). Do you have a >> sense for >> > whether this requires a significant amount of additional effort? >> >> A month at most. Maybe less. >> >> There are many examples of elements already implemented. The easiest way >> to do >> things is if you have a description of the polynomial space in some way. >> Take >> a look at the FE_Poly class and how it is used in some of the other >> classes. >> Depending on how you describe the serendipity space, this may be almost >> everything you actually need -- or maybe there are more complications. >> >> The FE interface is very self contained. You won't have to touch the >> DoFHandler or any other class. All you have to describe are the shape >> functions, what kind of continuity you have across faces and vertices, >> how >> hanging nodes look like (likely the same as the FE_Q(2)), and a few small >> other pieces of information that one can often ignore at first. >> >> Best >> W. >> >> -- >> ------------------------------------------------------------------------ >> Wolfgang Bangerth email: [email protected] >> www: http://www.math.colostate.edu/~bangerth/ >> >> -- >> 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 a topic in the >> Google Groups "deal.II User Group" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/dealii/-dajKCmE2rM/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/dealii/4ef3fe2c-5310-7d02-8614-b2b757f51274%40colostate.edu >> . >> > -- 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 [email protected]. To view this discussion visit https://groups.google.com/d/msgid/dealii/ea2d1f63-96d7-4da5-9040-536dbe40b213n%40googlegroups.com.
