Thank you for your answer. Yes, I want to evaluate the quantity at quadrature points. This is a source term (Continuum Surface Force) that should be added to the (Navier-Stokes) equations.
On Friday, January 28, 2022 at 3:04:14 PM UTC-5 Wolfgang Bangerth wrote: > On 1/28/22 7:56 AM, [email protected] wrote: > > > > I am looking for a way to obtain the distribution of ∇.(∇C/|∇C|) where C > is > > the main variable and I have its distribution (values, gradients and > > laplacians) over the domain. This is used for finding the normal vector > and > > its divergence over the moving interface of two materials in a > simulation. I > > would appreciate any suggestions you might have. > > When you say "obtain the distribution of ..." do you mean that you want to > evaluate that quantity at individual (quadrature) points? Or what do you > want > to do with it? > > The quantity you are looking at is not well defined for the usual finite > elements: grad C is a disontinuous function, and taking the divergence is > going to exacerbate the problems with this expression. The question > therefore > is what you want to do with it. A common approach is to use it in a weak > formulation where you can integrate by parts to get rid of the divergence. > > 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/b3e7b312-e438-49ee-a049-09a68f9ffdb8n%40googlegroups.com.
