[CIG-SHORT] static simulations with friction, correction to step10 and step11 in examples/3d/hex8

[Brad Aagaard]

Hi all,

We found a small error in the parameters for the static friction 
examples in examples/3d/hex8. Thanks to Gilda Currenti for alerting us 
of this issue.

The friction implementation involves checks of the fault slip rate 
against a zero tolerance. This means that even static simulations need a 
reasonable time step if they use fault friction, otherwise the check of 
the nondimensionalized fault slip rate against a zero tolerance will 
fail when it should not.

The correction in examples/3d/hex8 is to set the time step in
pylithapp.cfg as shown below (added the last line shown):

# ----------------------------------------------------------------------
# problem
# ----------------------------------------------------------------------
[pylithapp.timedependent.formulation.time_step]
# Define the total time for the simulation and the default
# time step size.
total_time = 0.0*s ; total time of simulation
dt = 5.0*year



This will fix the issues with slip occurring in step10 (slip should be 
zero) and give correct slip results for step11. Examples step12, step13, 
and step14 are unaffected because they are quasi-static simulations with 
appropriate values for the time step.

Regards,
Brad