> I checked the assembly and solve of system and > assembly of residual several times, but my residual > remains constant after few iterations.
You can generate graphical output of your residual vector and check where the residual is large. This will tell you if it is the boundary, hanging nodes, or something else. > I have noticed, that in several tutorial steps is some treatment of > residuals in constrained dofs > https://urldefense.proofpoint.com/v2/url?u=https-3A__www.dealii.org_8.4.1_doxygen_deal.II_step-5F15.html-23MinimalSurfaceProblemcompute-5Fresidual&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=LwDAOT4x12XCR4ZZNGBxZkY2KMoZZB4PPe_DB8a69ZM&s=eIB-fNPAjPA1EqbYCYq81pqrMoW7d0O7YOXOrpxsAdU&e= > > > and > in > https://urldefense.proofpoint.com/v2/url?u=https-3A__www.dealii.org_8.4.1_doxygen_deal.II_step-5F42.html-23PlasticityContactProblemsolve-5Fnewton&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=LwDAOT4x12XCR4ZZNGBxZkY2KMoZZB4PPe_DB8a69ZM&s=tK40yfgUDvq4mLJGxGLPXBo5iw0AFO-Tegooq3kj-FI&e= > > > is the following code > for (unsigned int n = start_res; n < end_res; ++n) > if (all_constraints.is_inhomogeneously_constrained(n)) > residual(n) = 0; Removing parts of the residual that are constrained (with code like above or constraints.set_zero()) may be necessary depending on the problem. Imagine a DoF that is fixed to a certain value (for example in contact areas in step-42). Of course the residual can not converge in that point so we set it to zero. The same holds for hanging nodes. > Could You tell me please a principle, how to assemble residual > in the similar way the matrix and rhs is assembled in step 40. You assemble it like a RHS and then set constrained entries to zero. -- Timo Heister http://www.math.clemson.edu/~heister/ -- 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.
