In addition to above, I thought I'd try VectorTools::compute_ nonzero_tangential_flux_constraints:
I did: std::set<types::boundary_id> no_tang_flux_boundaries; no_tang_flux_boundaries.insert(1); const Functions::ZeroFunction<dim> no_tang_bcs; typename FunctionMap<dim>::type no_tang_map; no_tang_map[1] = &no_tang_bcs; VectorTools::compute_nonzero_tangential_flux_constraints (dof_handler, 0, no_tang_flux_boundaries, no_tang_map, constraints); And this gives me a dimension miss match error - I'm guessing coming from the ZeroFunction, somehow, I thought I might need to use a fe.component_mask(velocities), but this isn't one of the arguments. Where is the dimension miss match coming from?? On Monday, March 18, 2019 at 10:30:32 PM UTC, jane...@jandj-ltd.com wrote: > > No that's fair enough. > > I had thought the way I was doing it would be the equivalent of setting no > tangential stresses. I actually also did it this way as I wasn't sure how > you impose it strongly. > > To impose strongly - would you just use > VectorTools::compute_nonzero_tangential_flux_constraints > with the ZeroFunction? > or is there a function similar to compute_no_normal_flux_constraints? > > I'll try that and see if there's a difference. > > Thanks > > On Monday, March 18, 2019 at 8:22:31 PM UTC, Wolfgang Bangerth wrote: >> >> On 3/18/19 12:37 PM, jane...@jandj-ltd.com wrote: >> > >> > For the u_t=0 condition, I had been imposing weak. So basically, I have >> > separated a Neumann boundary condition into: >> > n.[pI-2e] = (n.[pI-2e]n)n + (n.[pI-2e]t)t >> > and saying that the second term on the rhs is 0 so disappears, and the >> first >> > term is known weakly imposed into >> > topstress_values[q_point]*fe_face_values.normal_vector[q_point] etc. >> > Is this not a valid way? >> >> I don't know. I don't, because I don't know how you impose the u.t=0 >> boundary >> condition weakly. The way this is typically done is via the Nitsche >> method >> (which is essentially what DG approaches use for all interior faces as >> well). >> But I'd have to spend substantially more time than I have thinking >> through the >> implications for the case you pose here... >> >> Best >> W. >> >> -- >> ------------------------------------------------------------------------ >> 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. For more options, visit https://groups.google.com/d/optout.
