Re: [deal.II] make_sparsity_pattern, make_flux_sparsity_pattern problem when elements are connected with vertex
Dear Wolfgang: Thanks for your reply and suggestions, I will go to the source code of them. Best, Yidong 在 2019年3月20日星期三 UTC+8下午9:09:40，Wolfgang Bangerth写道： > > On 3/19/19 10:39 PM, Yidong ZHAO wrote: > > > > While using a new kind of shape function, degrees of freedom on each > cell will > > couple to the degrees of freedom on other cells connected to the current > one > > by a common face or common vertex. > > > > From the description of make_flux_sparsity_pattern(), it can solve the > problem > > when two elements are connected by a common face, as depicted in > > elements_connected_by_common_line.png. > > > > But if it's the case as elements_connected_by_common_vertex.png, is > there any > > way to make_vertex_sparsity_pattern() ? > > Yidong, > there is currently no function in deal.II that does this. But it should > not be > too hard for you to write one (in which case I would suggest you > contribute it > to deal.II! :) ). > > In essence, the functions that build a sparsity pattern _simulate_ what > will > happen during assembly. They do not compute individual matrix elements, > but > investigate what entries will be written to, and those are the ones for > which > elements of the matrix are allocated in the sparsity pattern. You will > need to > do something similar for your case. > > It would probably be useful for you to take a look at how the existing > functions are implemented. > > Best > W. > > -- > > Wolfgang Bangerth email: bang...@colostate.edu > > 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[deal.II] Publications based on deal.II
All, we have always tried to keep track of publications that use deal.II here: https://dealii.org/publications.html We do this because it helps us get the grants that support development of deal.II and its user community funded. But it also helps those who want to use deal.II find out whether someone has use this software for that purpose before. As you can see from the graph at the top of the page, we are clearly moving in the right direction. At the same time, we are obviously also missing many publications in 2018/2019. We would love to hear from you if you know of a publication that is not listed there (specifically, here: https://dealii.org/publications.html#list). We've made the process of submitting entries much simpler than in the past. Here are a number of ways you can let us know: * Open a new issue via https://github.com/dealii/publication-list/issues/new and just copy-paste either a bibtex entry, or just the reference information * If you want to save us a bit of work, follow the process here: https://github.com/dealii/publication-list/blob/master/README.md * Or email the information directly to me or one of the other principal developers. Thanks in advance Wolfgang -- Wolfgang Bangerth email: bange...@colostate.edu 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [deal.II] make_sparsity_pattern, make_flux_sparsity_pattern problem when elements are connected with vertex
On 3/19/19 10:39 PM, Yidong ZHAO wrote: > > While using a new kind of shape function, degrees of freedom on each cell > will > couple to the degrees of freedom on other cells connected to the current one > by a common face or common vertex. > > From the description of make_flux_sparsity_pattern(), it can solve the > problem > when two elements are connected by a common face, as depicted in > elements_connected_by_common_line.png. > > But if it's the case as elements_connected_by_common_vertex.png, is there any > way to make_vertex_sparsity_pattern() ? Yidong, there is currently no function in deal.II that does this. But it should not be too hard for you to write one (in which case I would suggest you contribute it to deal.II! :) ). In essence, the functions that build a sparsity pattern _simulate_ what will happen during assembly. They do not compute individual matrix elements, but investigate what entries will be written to, and those are the ones for which elements of the matrix are allocated in the sparsity pattern. You will need to do something similar for your case. It would probably be useful for you to take a look at how the existing functions are implemented. Best W. -- Wolfgang Bangerth email: bange...@colostate.edu 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [deal.II] Obtaining the final position of the vertices
Thank you very much. With those functions in DofTools I should be able to do what I need. Best, David. On Tuesday, 19 March 2019 17:41:32 UTC+1, Wolfgang Bangerth wrote: > > On 3/19/19 9:57 AM, David F wrote: > > > > I am not sure how to answer your question. I'm using a very basic a > setup > > equivalent to step-8. Therefore, I have a solution vector with final > > displacements where each entry corresponds to the displacement of a dof. > My > > aim is to find the initial position of the vertices in the form of > > std::vector> and the final position (i.e., the initial > position + > > its displacement) in the same form. > > I see -- you are using the pre-existing mesh and want to interpret the > solution as the *displacement* to the mesh. > > If all you are interested in is to output the solution on the deformed > mesh, > you can call Data::build_patches() with the mapping argument, where you > use a > MappingQEulerian object initialized with your displacement vector. > > If you want to have a representation in the program, you can use the > function > in namespace DoFTools that returns a vector of support point locations for > each DoF, and then query your solution vector for the corresponding > displacements. You might have to juggle with the x, y, and z displacements > a > bit to get this right, but the infrastructure is all there. > > Best > W. > > -- > > Wolfgang Bangerth email: bang...@colostate.edu > > 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[deal.II] Re: advection diffusion with periodic boundaries
Hi Gary, I'm trying to solve a time dependent advection-diffusion equation with > periodic boundary conditions. Just a simple du/dt = D \nabla^2 u - v \dot > \grad u for now. I use a large diffusion constant, so stability shouldn't > be an issue. The solution behaves normally in the bulk, but some of the > mass gets reflected once the mass gets to a boundary. The total mass > (integral of u over space) then decreases each time it goes through the > boundary in one direction, and increases if the velocity is set to go the > other way. Any idea why this might be the case? The periodic boundary works > fine when its just diffusion and no advection. > Small technical question: What time stepping scheme are you using? You will probably be aware of it but any explicit scheme in this case has time step restrictions for the advective part this will be CFL (note this is not a sufficient condition) which scales like v\delta t / \delta x <= const. For the diffusive part the time step constraint is much more severe since it scales like D\delta t / (\delta x)^2 <= const. I implemented a similar (also periodic scheme) and I did not run into this trouble. Best, Konrad -- 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.
