Dear Roy, I discovered that the example 1 of FEMSystem (NS equation) uses NewtonSolver, that is, _diff_solver in libMesh::TimeSolver points to NewtonSolver. Where should I change the code to use PetscDiffSolver? Is there an example where I can take a look?
Thank you. Best, Adriano. 2016-03-10 14:08 GMT-03:00 Roy Stogner <royst...@ices.utexas.edu>: > > On Thu, 10 Mar 2016, Adriano Côrtes wrote: > > *1. Why only the timestep 0 printed the line bellow?* >> >> Nonlinear step: |du|/|u| = 0.99946, |du| = 194.712 >> > > That's only printed for intermediate nonlinear steps, IIRC. In later > time steps the problem is linear enough to converge in one > quasi-Newton step. > > *2. Why the number of linear iterations is so different from the libmesh >> page and my run? >> > > Probably those were generated with different PETSc solver options. We > pull $LIBMESH_OPTIONS from your environment, and some of the libMesh > developers habitually keep it set to more robust or to faster values > (for their problems) than the PETSc defaults. > > Also the finite elements types? * >> >> Libmesh page: >> >> Finite Element Types="LAGRANGE", "JACOBI_20_00" "LAGRANGE", "JACOBI_20_00" >> Infinite Element Mapping="CARTESIAN" "CARTESIAN" >> Approximation Orders="SECOND", "THIRD" "FIRST", "THIRD" >> > > This was generated with infinite element support enabled; looks like > your output was generated with it disabled. > > *3. Where in Libmesh the PETSc class SNES is used? >> > > In PetscNonlinearSolver for NonlinearImplicitSystem or in > PetscDiffSolver for FEMSystem. > > Or better asking does FEMSystem communicates in the solver level >> with SNES, or is only in the KSP level?* >> > > Either. With PetscDiffSolver it uses SNES, with NewtonSolver it just > uses KSP. > --- > Roy -- Adriano Côrtes ================================================= Research assistant High-performance Computing Center (NACAD) Federal University of Rio de Janeiro (UFRJ) ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140 _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
