On 12/6/18 4:43 PM, Oleg Kmechak wrote: > > Probably I understood how to set Dirichlet boundary condition using > interpolate_boundary_values() and specifying argument boundary_id(but not > tried it yet). But how about Neumann boundary condition? As I understand, > using custom boundary_id on boundary cell, and with any specification by > interpolate_boundary_values() will give me Neumman with zero flux, but I > can't > figure out how to set nonzero flux.
Neumann boundary values have to be implemented in a completely different way. They go into the variational form. You may want to take a look at my lectures on boundary values. > PS: A little out of topic question. Even if I solved my equation and have > the *solution* vector, but I can't figure out how to "access" it like to > function f(x,y)? It is done somehow by FEValue class? You can use FEFieldFunction if you need it at arbitrary points. If you need it at quadrature points, then FEValues is the way to go -- take a look at step-15, for example. Best WB -- ------------------------------------------------------------------------ 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]. For more options, visit https://groups.google.com/d/optout.
