Thank you Dr. Bangerth, this is exactly what I was missing. Best, Giselle
On Thursday, March 11, 2021 at 3:36:53 p.m. UTC-6 Wolfgang Bangerth wrote: > On 3/11/21 10:33 PM, Giselle Sosa Jones wrote: > > > > I have a diffusion problem where the diffusion coefficient K depends on > the > > solution at the previous time step and is therefore discontinuous. I am > trying > > to implement a weighted average for DG, which is similar to the standard > > average, with the difference that the weights are not 0.5, but a > weighted > > average with the value of K on each side of a face. I have been > > using VectorTools::point_value to evaluate approximate solutions at > given > > points, but now I need to evaluate those approximate solutions at the > two > > neighboring cells. Do you have any idea about to how to approach this? > > Giselle, > VectorTools::point_value() is not the way to do this. It's extremely > expensive > to evaluate solutions this way, and as you noticed already, it's not the > right > tool anyway at places where the solution is discontinuous. > > The way this is supposed to work is by using FEValues/FEFaceValues to > evaluate > an existing solution at the quadrature points. You should take a look at > step-15 and how it evaluates the previous solution when it builds the > matrix/rhs for the current nonlinear step. > > Best > Wolfgang > > > -- > ------------------------------------------------------------------------ > 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 dealii+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/053bc625-f243-403e-ac8b-4b366abcf7fbn%40googlegroups.com.
