Dear developers,
I am trying to understand the FEMSystem framework, and the first thing I
did was to run the example 1, but the output I'm obtaining from the default
run (using make and run.sh) is completely different from the one in
http://libmesh.github.io/examples/fem_system_ex1.html
Bellow is my output
cortesam@Adrianos-MacBook-Pro
~/libmesh/petsc-3.6-g/install/examples/fem_system/ex1 $ ./run.sh
***************************************************************
* Running Example fem_system_ex1:
* example-opt
***************************************************************
*** Warning, This code is deprecated, and likely to be removed in future
library versions! ./include/libmesh/auto_ptr.h, line 270, compiled Feb 10
2016 at 13:48:42 ***
Mesh Information:
elem_dimensions()={2}
spatial_dimension()=2
n_nodes()=1681
n_local_nodes()=1681
n_elem()=400
n_local_elem()=400
n_active_elem()=400
n_subdomains()=1
n_partitions()=1
n_processors()=1
n_threads()=1
processor_id()=0
EquationSystems
n_systems()=1
System #0, "Navier-Stokes"
Type "Implicit"
Variables={ "u" "v" } "p"
Finite Element Types="LAGRANGE" "LAGRANGE"
Approximation Orders="SECOND" "FIRST"
n_dofs()=3803
n_local_dofs()=3803
n_constrained_dofs()=320
n_local_constrained_dofs()=320
n_vectors()=2
n_matrices()=1
DofMap Sparsity
Average On-Processor Bandwidth <= 38.9716
Average Off-Processor Bandwidth <= 0
Maximum On-Processor Bandwidth <= 59
Maximum Off-Processor Bandwidth <= 0
DofMap Constraints
Number of DoF Constraints = 320
Number of Heterogenous Constraints= 41
Average DoF Constraint Length= 0
Solving time step 0, time = 0
Assembling the System
Nonlinear Residual: 8.91374
Linear solve starting, tolerance 0.001
Linear solve finished, step 23, residual 0.148405
Trying full Newton step
Current Residual: 0.151381
Nonlinear step: |du|/|u| = 0.99946, |du| = 194.712
Assembling the System
Nonlinear Residual: 0.151381
Linear solve starting, tolerance 0.000151381
Linear solve finished, step 324, residual 8.33816e-05
Trying full Newton step
Current Residual: 0.000532267
Nonlinear solver converged, step 1, residual reduction 5.9713e-05 < 0.001
Nonlinear solver relative step size 0.0541853 > 0.001
u(1/3,1/3) = (-0.121174, 0.0709801, 0)
Solving time step 1, time = 0.005
Assembling the System
Nonlinear Residual: 0.000532267
Linear solve starting, tolerance 5.32267e-07
Linear solve finished, step 1072, residual 1.04563e-08
Trying full Newton step
Current Residual: 3.6894e-09
Nonlinear solver converged, step 0, residual reduction 4.139e-10 < 0.001
Nonlinear solver converged, step 0, relative step size 0.000768437 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 2, time = 0.01
Assembling the System
Nonlinear Residual: 3.6894e-09
Linear solve starting, tolerance 3.6894e-12
Linear solve finished, step 2988, residual 4.94884e-20
Trying full Newton step
Current Residual: 3.70259e-15
Nonlinear solver converged, step 0, residual reduction 4.1538e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 7.2649e-08 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 3, time = 0.015
Assembling the System
Nonlinear Residual: 3.70259e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2387, residual 6.75488e-26
Trying full Newton step
Current Residual: 2.86976e-15
Nonlinear solver converged, step 0, residual reduction 3.21948e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 2.57965e-15 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 4, time = 0.02
Assembling the System
Nonlinear Residual: 2.86976e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2264, residual 3.88067e-26
Trying full Newton step
Current Residual: 3.00722e-15
Nonlinear solver converged, step 0, residual reduction 3.37368e-16 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 5, time = 0.025
Assembling the System
Nonlinear Residual: 3.00722e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 1587, residual 3.93109e-26
Trying full Newton step
Current Residual: 3.00354e-15
Nonlinear solver converged, step 0, residual reduction 3.36956e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 1.52755e-15 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 6, time = 0.03
Assembling the System
Nonlinear Residual: 3.00354e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 1500, residual 4.08942e-26
Trying full Newton step
Current Residual: 2.89034e-15
Nonlinear solver converged, step 0, residual reduction 3.24256e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 2.15553e-14 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 7, time = 0.035
Assembling the System
Nonlinear Residual: 2.89034e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 1618, residual 4.15309e-26
Trying full Newton step
Current Residual: 2.76649e-15
Nonlinear solver converged, step 0, residual reduction 3.10363e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 2.50199e-16 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 8, time = 0.04
Assembling the System
Nonlinear Residual: 2.76649e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2396, residual 8.42985e-26
Trying full Newton step
Current Residual: 2.86854e-15
Nonlinear solver converged, step 0, residual reduction 3.21811e-16 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 9, time = 0.045
Assembling the System
Nonlinear Residual: 2.86854e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2846, residual 5.20961e-26
Trying full Newton step
Current Residual: 2.69779e-15
Nonlinear solver converged, step 0, residual reduction 3.02656e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 1.50625e-14 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 10, time = 0.05
Assembling the System
Nonlinear Residual: 2.69779e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2429, residual 6.72758e-26
Trying full Newton step
Current Residual: 2.78119e-15
Nonlinear solver converged, step 0, residual reduction 3.12011e-16 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 11, time = 0.055
Assembling the System
Nonlinear Residual: 2.78119e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2819, residual 6.70115e-26
Trying full Newton step
Current Residual: 2.93064e-15
Nonlinear solver converged, step 0, residual reduction 3.28778e-16 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 12, time = 0.06
Assembling the System
Nonlinear Residual: 2.93064e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2658, residual 5.47546e-26
Trying full Newton step
Current Residual: 2.79907e-15
Nonlinear solver converged, step 0, residual reduction 3.14017e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 5.5229e-14 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 13, time = 0.065
Assembling the System
Nonlinear Residual: 2.79907e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2359, residual 3.64948e-26
Trying full Newton step
Current Residual: 2.64323e-15
Nonlinear solver converged, step 0, residual reduction 2.96534e-16 < 0.001
Nonlinear solver converged, step 0, relative step size 9.49509e-15 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
Solving time step 14, time = 0.07
Assembling the System
Nonlinear Residual: 2.64323e-15
Linear solve starting, tolerance 1e-12
Linear solve finished, step 2327, residual 3.48849e-26
Trying full Newton step
Current Residual: 2.70471e-15
Nonlinear solver converged, step 0, residual reduction 3.03432e-16 < 0.001
u(1/3,1/3) = (-0.12115, 0.0709841, 0)
***************************************************************
* Done Running Example fem_system_ex1:
* example-opt
***************************************************************
*I have several questions:*
*1. Why only the timestep 0 printed the line bellow?*
Nonlinear step: |du|/|u| = 0.99946, |du| = 194.712
*2. Why the number of linear iterations is so different from the libmesh
page and my run? 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"
*3. Where in Libmesh the PETSc class SNES is used? Or better asking does
FEMSystem communicates in the solver level with SNES, or is only in the KSP
level?*
Thank you very much.
Adriano Cortes.
====================================
Researcher
High Performance Computing Center (NACAD)
Federal University of Rio de Janeiro (UFRJ)
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