[petsc-users] SNES-norm is zero all the time

Wed Feb 3 11:39:26 CST 2021

I am not running an specific example. Attached is  my code. and when I wun with
./step5.out -snes_monitor -snes_fd_color -ts_monitor -snes_converged_reason -pc_type lu

it seems it does not solve anything because the output is like:

    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
1 TS dt 0.005 time 0.005
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
2 TS dt 0.005 time 0.01
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
3 TS dt 0.005 time 0.015
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
4 TS dt 0.005 time 0.02
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
5 TS dt 0.005 time 0.025
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
6 TS dt 0.005 time 0.03
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
7 TS dt 0.005 time 0.035
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
8 TS dt 0.005 time 0.04
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
9 TS dt 0.005 time 0.045
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
10 TS dt 0.005 time 0.05
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
11 TS dt 0.005 time 0.055
copy!
    0 SNES Function norm 0.000000000000e+00
  Nonlinear solve converged due to CONVERGED_FNORM_ABS iterations 0
.......
________________________________
From: Jed Brown <jed at jedbrown.org>
Sent: Wednesday, February 3, 2021 11:19 AM
To: Sepideh Kavousi <skavou1 at lsu.edu>; petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>
Subject: Re: [petsc-users] SNES-norm is zero all the time

Sepideh Kavousi <skavou1 at lsu.edu> writes:

> Hello,
> I have a very stupid problem that I am really ashamed of asking but it has been with me for days and I do not know what to do. I want to solve the Javier stokes equation with finite difference method.

Could you run with -snes_monitor -snes_converged_reason -pc_type lu?

> When I wanted to run the code, the snes norm value does not change and i get an error for timestep convergence. I thought I might do something wrong so, I tried to simplify the equation I want to solve to an easy form, given as: u_t=u_x +u_y Where _t is the time derivative and _x and _y are the derivative in x and y direction. When I want to solve this problem, it still does not do anything at all and the snes function norm is zero all the time. I know I am missing something but does anyone have any idea what should I check in my code. The answers does not change with time. Best, Sepideh
>
>
> Get Outlook for iOS<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Faka.ms%2Fo0ukef&data=04%7C01%7Cskavou1%40lsu.edu%7C07c0cc86cc4d4100e28a08d8c8680396%7C2d4dad3f50ae47d983a09ae2b1f466f8%7C0%7C0%7C637479696353544458%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=A7xZE31UylQvnMnTFIcZj60GToFHW%2FsumLS9kIISEWo%3D&reserved=0>
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