Problems with basal sliding when applying Porous Solver

Extension of Elmer in computational glaciology
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glebcher
Posts: 9
Joined: 07 Apr 2018, 17:58
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Problems with basal sliding when applying Porous Solver

Post by glebcher »

Dear Elmer users,

I am trying to introduce basal sliding into a thermo-mechanically coupled model for a polythermal mountain glacier. I use snow/firn rheology (Porous Solver). If I apply no-slip conditions at the bedrock, the case works. But when I set the basal boundary condition as described in Elmer/Ice Wiki (http://elmerfem.org/elmerice/wiki/doku. ... ers:porous), no convergence is seen even after 10 000 linear system solver iterations. The error message is:

Code: Select all

      9990 0.9374E+00
     10000 0.9391E+00
     10001 0.9391E+00
NUMERICAL ERROR:: IterSolve: Too many iterations was needed.
Note: The following floating-point exceptions are signalling: IEEE_DENORMAL
The sif and mesh files are attached.
porous_thermomech_slide.sif
(5.43 KiB) Downloaded 4 times
Data.rar
(346.86 KiB) Downloaded 4 times
Also, it may worth mentioning that the solver is restarted from the previous solution (unfortunately, the restart file is too large to be attached). I will also provide additional information, if needed. I do not know what is incorrect and how to obtain convergence. So, I would be very grateful for any help or advice.

Regards,
Gleb
Last edited by glebcher on 23 Nov 2020, 18:16, edited 3 times in total.
fgillet
Posts: 42
Joined: 30 Sep 2010, 16:58

Re: Problems with basal sliding when applying Porous Solver

Post by fgillet »

Hello;
if the iterative solver is not converging you can try to use a direct solver (umfpack in serial or Mumps in parallel) this should always work (at least if you have enough memory).

If the direct method is too slow you may still try to use another iterative solver and/or preconditionner.
glebcher
Posts: 9
Joined: 07 Apr 2018, 17:58
Antispam: Yes

Re: Problems with basal sliding when applying Porous Solver

Post by glebcher »

Hello, fgillet!

Thank you very much for your reply and recommendations. I will try to do everything that you suggested. Unfortunately, I have not managed to attach any files, although not all of them were too large. I will try to fix it somehow.

Regards,
Gleb
glebcher
Posts: 9
Joined: 07 Apr 2018, 17:58
Antispam: Yes

Re: Problems with basal sliding when applying Porous Solver

Post by glebcher »

An update to the post: the sif and mesh files are now attached and available.

Regards,
Gleb
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