[CIG-SHORT] Problems with viscoelastic model with Pylith

[Francisco Delgado]

Dear Pylith developers,

I've been running simulations of a pressurised magma chamber surrounded by
a viscoelastic shell with an exponential pressure function of the form
P=Pf(1-exp(-t/tau)) but the solutions yields numerical instabilities like
in the attached plot. I suspect it's an issue with the solver, but I don't
know what to look for. My solver parameters are the following which work
well for static linear elastic problems



[pylithapp.petsc]



# Preconditioner settings.

pc_type = asm

sub_pc_factor_shift_type = nonzero



# Convergence parameters.

ksp_rtol = 1.0e-12

ksp_atol = 1.0e-12

ksp_max_it = 500

ksp_gmres_restart = 50



# Linear solver monitoring options.

ksp_monitor = true

ksp_view = true

ksp_converged_reason = true



log_summary = true

# start_in_debugger = true



Any insight is appreciated

Thanks

-- 
--------------------------------------------------------
Francisco Delgado
PhD candidate, Geological Sciences
Cornell University
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