Wolfgang, > How does GetDP do that? Is it a global flag that is set once?
In GetDP the user defines in the input script an object called "Jacobian", which can be different for each domain region. When setting up an integral term in the weak formulation then, you have to specify which jacobian method will be used to evaluate the integrals. In analogy to Deal.II terminology, you define a certain mapping or FEValues object (I am not exactly sure which class calculates the jacobian in DealII), which applies to different parts of the triangulation (e.g. separated by material_id). Then whenever evaluating integrals in a certain part of the triangulation, the corresponding mapping/FEValue object would invoke the corresponding appropriate JxW that corresponds to that triangulartion object. > What if one wanted to solve a coupled problem where one PDE is axisymmetric but another > one is fully 3d? In that case the domains/meshes should be different right? One domain is 2D the other is 3D. In that case one has just to define the desired jacobian to the domain that is axisymmetric, and declare that this jacobian is to be used when writing the corresponding weak form terms. On Thursday, November 14, 2019 at 4:32:37 PM UTC+2, Wolfgang Bangerth wrote: > > > > It is not cumbersome at all to implement it in the assembly function. I > > implemented it, and it is just one extra line of code in the assembly > > function. The big advantage I find in somehow including that 2πr factor > in the > > JxW(), applies when having a big code that solves several PDEs on the > same > > domain, using 3D, 2D or axisymmetric geometries in general. In that > case, it > > would be advantageous not to need to change every single assembly > function > > depending on what kind of geometry you have, just use a different > FEValues and > > implicitly include that factor on the JxW(). This would be in line with > the > > generic programming approach of Deal.II for dimension-independent > > implementations, using the <dim> templates. > > How does GetDP do that? Is it a global flag that is set once? What if one > wanted to solve a coupled problem where one PDE is axisymmetric but > another > one is fully 3d? > > > > I think it was my big misunderstanding. I misinterpreted some points in > this > > < > https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdealii.org%2Fdeveloper%2Fdoxygen%2Fdeal.II%2FclassMappingManifold_1_1InternalData.html&data=02%7C01%7CWolfgang.Bangerth%40colostate.edu%7C553194e059364721c87308d768ec7f3e%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637093237276121270&sdata=Eke2ZtsNex86tnv%2FVM2gjgYiOYLEFrsklc5GSRnd6Tc%3D&reserved=0> > > > > documentation page, but it was completely my mistake and I think the > page is > > well-written. I could not understand how to connect the manifold to the > > Mapping, but now it is clear to me. Thank you very much for clarifying. > > > > > If you wanted to, that would > > > make for a nice pull request to get used to contributing to the > library! ;-) ) > > > > Thank you for the invitation. I will try to see whether and what I can > contribute. > > OK, thank you in advance! We're looking forward to it ;-) > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > <javascript:> > 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 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 on the web visit https://groups.google.com/d/msgid/dealii/e67c9539-25b4-4800-b619-a32b9d48d9f8%40googlegroups.com.
