On 23 Apr 2014, at 14:52, David Ham <[email protected]> wrote:
> > > On Wednesday, April 23, 2014, Garth N. Wells <[email protected]> wrote: > > On 16 Apr 2014, at 12:08, David Ham <[email protected]> wrote: > > > Hi Jack, > > > > The student who was working on isoparametric mappings last summer didn't > > get very far, however we were very fortunate to host Martin Alnæs for six > > weeks this spring. We designed, and he implemented, the UFL layer changes > > needed to get isoparametric in. We still have some legwork to do in our FFC > > branch to get those changes into Firedrake and I believe the equivalent > > work for Dolfin is still underway, but there is progress and we hope to > > have isoparametric by the summer. > > > > On the shell subject, Firedrake now supports simulation on extruded shells > > formed of triangular prism elements. I'm not sure if that helps you but > > you're welcome to give it a try. > > > > Jack is referring to a different type of shell - he’s referring to shells in > the structural mechanics sense rather than a spherical shell. > > > Firedrake is not limited to spherical shells. One can take any immersed > manifold and extrude in an arbitrary direction. > Nice, but the thread is about solving the equations for structural shell models and not extruding meshes, e.g. solving the Koiter or Naghdi type shell equations. A major issue for these types of models is supporting function spaces and/or geometric concepts in UFL to resolve/distinguish between in-plane and out-of-plane displacement components, and in cases how to perform the local element tricks used some shell formulations. Garth > David > > Garth > > > Regards, > > > > David > > > > > > > > On 16 April 2014 10:39, Jack HALE <[email protected]> wrote: > > Hi Corrado! > > > > Sorry for the slow reply on here, I know we have discussed this > > privately, but of course this is the best place for discussion. > > > > 1. First half of the presentation; My understanding of the current > > 'PDE on Manifold' functionality in FEniCS is that the weak form cannot > > include terms relating to the geometry of the manifold. i.e. it would > > be natural to have terms such as the fundamental form expressed > > through UFL which you could then define the shell model. > > > > I have seen someone discuss this idea before here: > > http://www.mail-archive.com/[email protected]/msg08932.html > > > > albeit in the context of isoparametric mappings. I think though, that > > isoparametric mapping is just relating R^3->E^3 and the shell concept > > is relating R^2->E^3, the efforts towards shell models should work > > within bringing isoparametric mappings to FEniCS. > > > > @David Ham: I remember David Ham discussed with me that he had a > > student working isoparametric mappings, did anything come of it? > > > > 2. Second half of the presentation; local projections. As you can see > > I have done some simple local projections at the linear algebra level > > (ie. post assembly), but I do not think this is a suitable path for > > implementing the MITC operators which are significantly more > > complicated. One initial option would be to do the full mixed problem, > > at the expense of engendering extra unknowns. Also you suggested in > > our private email that we could do these local projections using a > > custom C++ kernel/assembly routine. > > > > I can see there are still some problems with the RT elements on > > manifolds, it would be important for this functionality to work first: > > > > http://fenicsproject.org/pipermail/fenics/2014-March/001340.html > > > > And only two threads up from this one, this discussion seems pertinent: > > > > http://fenicsproject.org/pipermail/fenics/2014-March/001371.html > > > > Another option is that we avoid this second piece of functionality and > > go with trying to get DG-Koiter shell models working first which work > > which are rotation-free and use standard element constructions. > > > > @Garth Wells: I know this is something Garth Wells is an expert on so > > perhaps it is the best path forward for now? > > > > 3. Generality. So I know a lot about shells, but not about other PDEs > > on manifolds. I remember Douglas Arnold mentioned that any approach > > implemented in FEniCS > > should be as general as possible. Any comments on this? > > > > Kind regards, > > ----- > > Dr. Jack S. Hale > > > > Research Associate > > > > University of Luxembourg > > Campus Kirchberg G005 > > Phone +352 44 66 44 5236 > > [email protected] > > > > Latest publications and conferences: http://goo.gl/rNiISG > > ORCID: http://orcid.org/0000-0001-7216-861X > > Google Scholar: http://scholar.google.com/citations?user=Fx9lQ7MAAAAJ&hl=de > > _______________________________________________ > > fenics mailing list > > [email protected] > > http://fenicsproject.org/mailman/listinfo/fenics > > > > > > > > -- > > Dr David Ham > > Departments of Mathematics and Computing > > Imperial College London > > > > http://www.imperial.ac.uk/people/david.ham > > _______________________________________________ > > fenics mailing list > > Garth N. Wells > Department of Engineering, University of Cambridge > http://www.eng.cam.ac.uk/~gnw20 > > > > -- > Dr David Ham > Departments of Mathematics and Computing > Imperial College London > > http://www.imperial.ac.uk/people/david.ham _______________________________________________ fenics mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics
