[cig-commits] [commit] baagaard/dynrup-new-lagrange, baagaard/fix-faults-intersect, knepley/fix-faults-parallel, master: Add more info about solver tolerances for friction in quasi static simulations. (f795a04)

[cig_noreply at geodynamics.org]

Repository : https://github.com/geodynamics/pylith

On branches: baagaard/dynrup-new-lagrange,baagaard/fix-faults-intersect,knepley/fix-faults-parallel,master
Link       : https://github.com/geodynamics/pylith/compare/85fe9961fb58cc7323dc26e78085e3f9b7748433...d42a67a6ec678bc8486e0f74f439efbe2f82a25d

>---------------------------------------------------------------

commit f795a04f86cc54c1eee4cf4e160c0a7257c1bd26
Author: Brad Aagaard <baagaard at usgs.gov>
Date:   Sun Jun 1 11:14:56 2014 -0700

    Add more info about solver tolerances for friction in quasi static simulations.


>---------------------------------------------------------------

f795a04f86cc54c1eee4cf4e160c0a7257c1bd26
 .../boundaryconditions/boundaryconditions.lyx      | 86 ++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/doc/userguide/boundaryconditions/boundaryconditions.lyx b/doc/userguide/boundaryconditions/boundaryconditions.lyx
index 4817279..eec18e4 100644
--- a/doc/userguide/boundaryconditions/boundaryconditions.lyx
+++ b/doc/userguide/boundaryconditions/boundaryconditions.lyx
@@ -4981,6 +4981,92 @@ friction.db_properties = spatialdata.spatialdb.SimpleDB
 friction.db_properties.iohandler.filename = friction.spatialdb
 \end_layout
 
+\begin_layout Quote
+
+\series bold
+\color red
+Warning:
+\color inherit
+ 
+\series default
+\color none
+Use of the dynamic rupture implementation in a quasi-static simulations
+ requires use of the nonlinear solver and careful selection of linear and
+ nonlinear solver tolerances.
+ A key issue is making sure the linear solver toleance is tighter (smaller)
+ than the tolerance used to detect slip (fault 
+\family typewriter
+\color inherit
+zero_toelerance
+\family default
+\color none
+).
+ As a result, the linear and solver absolute tolerances should be used to
+ for convergence, not the relative tolerances.
+ The code below illustrates the relevant parameters and example values.
+ The values can be scaled to change the overall desired tolerances.
+\end_layout
+
+\begin_layout LyX-Code
+[pylithapp.problem.interfaces.fault]
+\end_layout
+
+\begin_layout LyX-Code
+zero_tolerance = 1.0e-11
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+[pylithapp.petsc]
+\begin_inset Newline newline
+\end_inset
+
+# Linear solver tolerances
+\begin_inset Newline newline
+\end_inset
+
+ksp_rtol = 1.0e-20
+\begin_inset Newline newline
+\end_inset
+
+ksp_atol = 1.0e-12
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+# Nonlinear solver tolerances
+\begin_inset Newline newline
+\end_inset
+
+snes_rtol = 1.0e-20
+\begin_inset Newline newline
+\end_inset
+
+snes_atol = 1.0e-10
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+# Set preconditioner for friction sensitivity solve
+\begin_inset Newline newline
+\end_inset
+
+friction_pc_type = asm
+\begin_inset Newline newline
+\end_inset
+
+friction_sub_pc_factor_shift_type = nonzero
+\end_layout
+
 \begin_layout Standard
 The prescribed traction perturbation is specified using the same fault coordinat
 e system as the slip directions in the kinematic ruptures.