Re: [deal.II] Re: Calculate surface integral over a boundary

[Dragan Nikolic]

To answer my own question: finally I resolved a problem. I've been always getting zeros for the surface integral. It was a typo in the _expression_ I have been using (c is the dof, D is diffusivity):      but I used q index for c by mistake. Thanks for the help, that code snipped helped me when I looked at the implementation of  get_function_gradients (and the function it calls do_function_derivatives). Dragan On 23/09/16 18:24, dragniko...@gmail.com wrote: And one more thing I forgot. Although it is typically a post-processing task I would like to get it during the integration (the problem is transient). On Friday, September 23, 2016 at 5:56:16 PM UTC+1, Jean-Paul Pelteret wrote: Hi Dragan, What is it that you're trying to evaluate? Although you don't specifically mention it, as you're wanting to do this in post-processing I presume that you're wanting to evaluate something to do with the solution? If so, then you can use the get_function_values and get_function_gradients associated with the FEFaceValues class to extract the solution at the face quadrature points. As a further example, in step-44 a boundary integral is evaluated to compute the nodal contributions of a force applied to a surface of a body. I hope this helps. J-P On Friday, September 23, 2016 at 6:29:37 PM UTC+2, dragn...@gmail.com wrote: Hello guys, I searched the forum about how to calculate the surface integral over a boundary (during the post-processing) and found one post, where he was directed to the step-12. I am not sure if I can understand from there. Any directions how to do it or some other place to look? Thanks. Dragan -- 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/vCRhuC2j9YE/unsubscribe. To unsubscribe from this group and all its topics, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout. -- 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.