Dear Prof. Bangerth, Thanks for your instant hint.
I'll get the hessian first and compute the divergence of the vector gradient explicitly. Regards, Lixing On Wednesday, July 21, 2021 at 10:46:28 AM UTC+8 Wolfgang Bangerth wrote: > On 7/20/21 8:07 PM, Lixing Zhu wrote: > > > > However, I am trying to implement some stabilization technique that > involves > > 2nd order derivatives of the shape function, like the divergence of the > > symmetric gradient of the displacement vector (actually, the shape > function). > > For now, I can only think of selecting the components from the Hessian > of the > > shape function to compute the div of the symmetric gradient. Is there > any way > > in deal.ii to directly extract such values like divergence of the > symmetric > > gradient of shape functions? > > There is no easy way. You'll have to compute the tensor of second > derivatives > and sum over the appropriate set of elements. > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > 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/c1936ba9-7bcc-4f50-b020-fbfa3ba8cf85n%40googlegroups.com.
