Why does this petsc-maint message have a messed up Reply-To: header? Matt
---------- Forwarded message ---------- From: Yann Jobic <yann.jo...@univ-amu.fr> Date: Wed, Nov 22, 2017 at 12:39 PM Subject: [petsc-users] 2 Dirichlet conditions for one Element in PetscFE To: PETSc <petsc-us...@mcs.anl.gov> Hello, I've found a strange behavior when looking into a bug for the pressure convergence of a simple Navier-Stokes problem using PetscFE. I followed many examples for labeling boundary faces. I first use DMPlexMarkBoundaryFaces, (label=1 to the faces). I find those faces using DMGetStratumIS and searching 1 as it is the value of the marked boundary faces. Finally i use DMPlexLabelComplete over the new label. I then use : ierr = PetscDSAddBoundary(prob, DM_BC_ESSENTIAL, "in", "Faces", 0, Ncomp, components, (void (*)(void)) uIn, NWest, west, NULL);CHKERRQ(ierr); in order to impose a dirichlet condition for the faces labeled by the correct value (west=1, south=3,...). However, the function "uIn()" is called in all the Elements containing the boundary faces, and thus impose the values at nodes that are not in the labeled faces. Is it a normal behavior ? I then have to test the position of the node calling uIn, in order to impose the good value. I have this problem for a Poiseuille flow, where at 2 corner Elements i have a zero velocity dirichlet condition (wall) and a In flow velocity one. The pressure is then very high at the corner nodes of those 2 Elements. Do you think my pressure problem comes from there ? (The velocity field is correct) Many thanks, Regards, Yann PS : i'm using those runtime options : -vel_petscspace_order 2 -pres_petscspace_order 1 \ -ksp_type fgmres -pc_type fieldsplit -pc_fieldsplit_type schur -pc_fieldsplit_schur_fact_type full \ -fieldsplit_velocity_pc_type lu -fieldsplit_pressure_ksp_rtol 1.0e-10 -fieldsplit_pressure_pc_type jacobi --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. https://www.avast.com/antivirus -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
