Hi IIiya, On Thursday, February 22, 2018 at 11:55:33 AM UTC+1, Bryukhanov Ilya wrote: > > Denis, thanks a lot for the answer! > > I think that on the first step I can use usual > "interpolate_boundary_values + apply_boundary_values" functions, >
the outline I gave above is agnostic to "first step"/"other steps", you would call VectorTools::interpolate_boundary_values() regardless stage to get constraints into the ConstraintMatrix object. If you do Newton-Raphson and solve for increments, at the first non-linear step you should have all constraints (hanging nodes + non-zero Dirichlet for a given step in quasi-static(?) loading), and for consequent steps only hanging nodes plus zero Dirichlet. Please read this module: https://www.dealii.org/developer/doxygen/deal.II/group__constraints.html This code-gallery may help in figuring out how to do this: https://www.dealii.org/developer/doxygen/deal.II/code_gallery_Quasi_static_Finite_strain_Compressible_Elasticity.html > that transform the global matrix: columns of the constrained nodes become > zero columns with diagonal non-zero entries. > > In a time loop I have to account boundary condition without modifing > global matrix. While looping over dirichlet constrained cells > I call the function > "hanging_node_constraints.distribute_local_to_global(cell_rhs, > local_dof_indices, system_rhs, cell_matrix)" > which modifies the system_rhs vector by adding columns from constrained > nodes, which are actually zero in global matrix. > Nope, if your "hanging_node_constraints" indeed contains only constraints from hanging nodes, you won't see any contribution to the RHS from it as constraints are homogeneous (ie. you wont' have u_{123} = 456 from hanging nodes). > > Also I need to add components to rhs vector from the force boundary > conditions. > that's a different story, just do integration over faces and distribute as usual. > > However, I have to somehow account Dirichlet boundary conditions as in > previous step I didn't use any boundary values. The function > use ConstraintMatrix which has non-zero Dirichlet BC constraints. > "interpolate_boundary_values(dof_handler, boundary_id, DirichletHandler, > boundary_values)" > gives me "boundary_values" variables that maps node numbers to dirichle > boundary. > > But I don't know how should I use it. What should I do with that variable > to account boundary conditions together with "distribute_local_to_global"? > > Thanks a lot in advance. Sorry for my misunderstanding. > Regards, Denis. -- 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.
