Hi Everyone, In case anyone ever follows this thread and needs to find the code associated with interpolate_boundary_values(), I found https://github.com/dealii/dealii/blob/master/include/deal.II/numerics/vector_tools.templates.h
I will report back on my implementation. Thanks, Ernesto On Tuesday, 21 January 2020 09:45:28 UTC+2, Ernesto Ismail wrote: > > Hi Daniel and J-P, > > Thanks for your advice. I will try what you suggest. > > I feel like a bit of an idiot here, but I can't seem to find the source > code for the interpolate_boundary_values() function. I've rooted around > various source folders on Git and most of them don't contain much e.g. > https://github.com/dealii/dealii/blob/master/source/numerics/vector_tools_project.cc > I > think I'm just not familiar enough with how the project is laid out. Can > anyone point me in the right direction? > > Thanks, > Ernesto > > On Wednesday, 15 January 2020 23:08:58 UTC+2, Jean-Paul Pelteret wrote: >> >> Hey Ernesto, >> >> I’ve used the approach outlined by Wolfgang and Daniel in my own work >> (multi physics problems, single DoFHandler with BC’s being transferred >> between a primary and secondary problem solved on subsets of the domain). >> Overall, it works really well so I’d back up their suggestion and recommend >> that you adopt it. Its mostly really just a question of finding common >> support points on the two surfaces, and seeing which DoF indices link up >> and transferring data from one solution vector to the other. I was looking >> though my code to see if I could share a snippet with you, but its so close >> in structure to the interpolate_boundary_values() (and still retains all of >> the original comments in the deal.II source :-) that its not really worth >> it. >> >> Cheers, >> J-P >> >> On 15 Jan 2020, at 07:48, Daniel Arndt <d.arn...@gmail.com> wrote: >> >> Ernesto, >> >> Imposing strong boundary conditions should not be overly difficult in >> this case. >> Just as Wolgang said you should have a look at >> interpolate_boundary_values() and replace the Function object evaluations >> on each cell by the function values given through >> a FEValues object initialized for your first solution. Assuming that you >> are using interpolatory ansatz functions, this interpolation has to happen >> at the support points of your target finite element. >> In particular, these support points should be the quadrature points for >> the FEValues object. >> >> Best, >> Daniel >> >> Am Di., 14. Jan. 2020 um 01:50 Uhr schrieb Ernesto Ismail < >> ernest...@gmail.com>: >> >>> Dear Prof. Bangerth, >>> >>> Thank you for your reply. >>> >>> I would ideally have liked to impose the boundary conditions strongly >>> but it looks like doing so will not be straight-forward. I will do some >>> investigations into applying the boundary conditions weakly and attempt >>> that first. >>> >>> One approach I had tried was to use Lobatto quadrature and use a >>> quadrature point history data structure to transfer the solution at the >>> boundary. The problem with this approach was that the differing element >>> types lead to some strange behaviours along the boundary. >>> >>> Thanks again, >>> Ernesto >>> >>> On Thursday, 9 January 2020 23:43:27 UTC+2, Wolfgang Bangerth wrote: >>>> >>>> >>>> Ernesto, >>>> >>>> > I am currently working with a staggered coupled system where I am >>>> solving >>>> > several finite element problems in sequence. Up until now my boundary >>>> > conditions have been fairly straightforward and I've been able to get >>>> > meaningful results from my work. >>>> > >>>> > The finite element schemes I use for each step are fairly different, >>>> with some >>>> > being discontinuous and of varying orders. >>>> > >>>> > I am now in a position where I need to use the solution of one of my >>>> steps as >>>> > the boundary condition for the next (I actually need to combine two >>>> of them >>>> > with a simple arithmetic function, but baby steps for now). I presume >>>> I need >>>> > to use some sort of projection to achieve this, but I'm not exactly >>>> sure how >>>> > to go about it. I thought to try and use >>>> the project_boundary_values() >>>> > function to do what I need, but I am unsure how I would structure >>>> > the boundary_functions argument. >>>> >>>> Do you need to enforce these boundary conditions strongly? If you can >>>> enforce >>>> them weakly, then the solution of one problem only enters the weak form >>>> of >>>> another problem (in that case through a boundary integral) and that is >>>> really >>>> not very different from the way we do this in other problems where we >>>> have >>>> multiple DoFHandlers -- e.g., in step-31. (Though my usual advice still >>>> holds >>>> true that I think everything becomes simpler if you pack everything >>>> into one >>>> DoFHandler). >>>> >>>> It gets more complicated if you want to impose strong boundary >>>> conditions. >>>> You've already found the FEFieldFunction function, but it's complicated >>>> and >>>> slow. A simpler way would be if you looked at the implementation of the >>>> interpolate_boundary_values() function and identified where it is >>>> asking the >>>> Function object for its values. That's the place where you'd need to >>>> somehow >>>> combine your existing solutions into something else and turn that into >>>> a >>>> constraint. >>>> >>>> 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 dea...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/dealii/832bb83a-7e04-4243-9524-64db1bfc9345%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/dealii/832bb83a-7e04-4243-9524-64db1bfc9345%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> -- >> 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 dea...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/dealii/CAOYDWbKY2%3D%2BBdWX4mh7guYEROFPT7mX8QR%3D4ED4KWymi_cD7Aw%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/dealii/CAOYDWbKY2%3D%2BBdWX4mh7guYEROFPT7mX8QR%3D4ED4KWymi_cD7Aw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> >> -- 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. 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