[CIG-SHORT] Linear convergence for nonplanar faults

[Josimar Alves da Silva]

Dear Brad, Matt and Charles,

I am running Pylith for a 2D friction model with gravity for a nonplanar
fault. I am finding that the linear solver does not converge when the fault
is included on the model. When the fault is not included on the model the
linear solver takes roughly 500 to 1000 iterations to converge. Please
refer to the attached "log_no_fault.cfg" file.

The three links below show previous discussions on linear convergence:

http://lists.geodynamics.org/pipermail/cig-short/2012-September/001123.html


http://lists.geodynamics.org/pipermail/cig-short/2008-December/000453.html


http://lists.geodynamics.org/pipermail/cig-short/2013-March/001320.html



As pointed out by Charles previously and also discussed on the links above,
overall, it seems that there are 3 main causes for convergence issues: 1)
Poor quality mesh; 2) incorrect solver settings; 3) Poor setup/initial
conditions.


For my set up, I am unable to make the linear solver to converge.


This is what I have done so far, based on recommendations from previous
discussions:


1) Make sure that the mesh has condition number and aspect ratios <1.5.
Please see attached presentation for histograms.

2) used the solver parameters shown on share/settings/
solver_fault_fieldsplit.cfg


I would like to know if there is anything else that I can do in order to
make the linear solver to converge. Any other advices to improve my
simulation would be very much appreciated.


You can find attached the pylith .cfg files that I am using and also the
log files for the case without the fault (log_no_fault.out) and with the
fault (log_with_fault.out).


I run my simulation using:


1) pylith no_fault.cfg > log_nor_fault.out

2) pylith no_fault.cfg   fault.cfg > log_with_fault.out



Thank you in advance for you help,

Josimar
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