Re: [petsc-users] Convergence issues for SNES NASM

I'm still relatively new to PETSc. I was using DMDASetUniformCoordinates and DMGetBoundingBox together. In hindsight, it was a very unnecessary thing to do. I think the simplest way to prevent anyone else from making the same mistake is to add a caveat to the DMGetBoundingBox documentation page.

Re: [petsc-users] Convergence issues for SNES NASM

On Thu, May 12, 2022 at 1:03 PM Takahashi, Tadanaga wrote: > Thank you for the feedback. We figured out what was causing the issue. We > were using DMGetBoundingBox > in order > to get the limits of the global domain, but gmin and

Re: [petsc-users] Convergence issues for SNES NASM

Thank you for the feedback. We figured out what was causing the issue. We were using DMGetBoundingBox in order to get the limits of the global domain, but gmin and gmax contained limits for the local subdomains when we ran the code

Re: [petsc-users] Convergence issues for SNES NASM

Your subdomain solves do not appear to be producing descent whatsoever. Possible reasons: 1) Your subdomain Jacobians are wrong (this is usually the problem) 2) You have some global coupling field for which local solves give no descent. (For this you want nonlinear elimination I think)

Re: [petsc-users] Convergence issues for SNES NASM

Can you add -snes_linesearch_monitor -sub_snes_linesearch_monitor -ksp_converged_reason and send the output?? "Takahashi, Tadanaga" writes: > Hello, > > We are working on a finite difference solver for a 2D nonlinear PDE with > Dirichlet Boundary conditions on a rectangular domain. Our goal is

[petsc-users] Convergence issues for SNES NASM

Hello, We are working on a finite difference solver for a 2D nonlinear PDE with Dirichlet Boundary conditions on a rectangular domain. Our goal is to solve the problem with parallel nonlinear additive Schwarz (NASM) as the outer solver. Our code is similar to SNES example 5