Math, It really depends on your problem. If outside of your simulation domain, you have a domain that has the same properties and the solution changes slowly that's probably a good approximation. If outside of your domain, the solution changes quickly that's probably a bad approximation. If your solution has a shock, your approximation will be totally off. If you are solving the heat equation, the approximation is probably fine.
Best, Bruno Le mar. 6 juin 2023 à 16:25, Mathieu <mathieu....@gmail.com> a écrit : > Hi Bruno, > > for a post-processing step, I have to evaluate my temperature field at > some points outside the mesh close to its boundary. > > I know that shape functions are not defined outside the mesh, that's why I > wanted to extrapolate them. > My idea was to use the gradient of the temperature field to come up with > an extrapolation. > But I do not know if that's reasonable. > > Best, > > Math > > Bruno Turcksin <bruno.turck...@gmail.com> schrieb am Di., 6. Juni 2023, > 21:55: > >> Math, >> >> The basis functions are not defined outside of an element, so you cannot >> extrapolate them outside of the mesh. What are you trying to achieve? >> >> Best, >> >> Bruno >> >> On Monday, June 5, 2023 at 4:59:28 PM UTC-4 Mathieu wrote: >> >>> Hello everyone, >>> >>> I was wondering if deal.II has built-in functions to evaluate continuous >>> finite element functions (FEQ) at points outside the mesh? >>> E.g.: given a point P in 2d/3d, which is not contained in the 2d/3d mesh >>> but close to the boundary, how could one evaluate (extrapolate) the FE >>> function at P? Or is it not a good idea to extrapolate shape functions? >>> >>> Thank you >>> Math >>> >> -- >> 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/RmYuqy3_3FY/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> dealii+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/dealii/99afba6c-3f6a-4990-8bf1-230beb186f4cn%40googlegroups.com >> <https://groups.google.com/d/msgid/dealii/99afba6c-3f6a-4990-8bf1-230beb186f4cn%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 a topic in the > Google Groups "deal.II User Group" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/dealii/RmYuqy3_3FY/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > dealii+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/CA%2BwBsdNUD7GXzGROLJg2hmW4Hqw1T%2BPyLMCDaz339C_9uG%2BxhQ%40mail.gmail.com > <https://groups.google.com/d/msgid/dealii/CA%2BwBsdNUD7GXzGROLJg2hmW4Hqw1T%2BPyLMCDaz339C_9uG%2BxhQ%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. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAGVt9eOPTMpZxY93DFdmCgh5t922JnZxkQj6BAFDEAmuDkhhdQ%40mail.gmail.com.
