[CIG-SHORT] Smoothing Issues

[Nick Wogan]

Brad and Charles,

Looks like Cubit isn't in the budget unfortunately, but I am slowly
learning LaGriT.

Things are looking better. Attached is an image of one mesh used, and the
resulting stresses which seem to be much smoother. I have run into another
problem- the iterative solver is not converging for this new mesh. For all
of the previously run simulations I have used the following PETSC settings.

# Set the solver options.
[pylithapp.petsc]
malloc_dump =
pc_type = asm
sub_pc_factor_shift_type = nonzero
ksp_rtol = 1.0e-8
ksp_atol = 1.0e-12
ksp_max_it = 5000
ksp_gmres_restart = 50
ksp_monitor = true
ksp_view = true
ksp_converged_reason = true
ksp_error_if_not_converged = true
log_summary = true

I changed the settings to a direct solver and it produced a solution:
[pylithapp.petsc]
snes_view = true
pc_type = lu

Now I am trying to fine the mesh further to hopefully produce a smoother
solution, but the neither solver is working. The iterative solver doesn't
converging to a reasonable value. The direct solver runs out of memory. Is
there a better iterative solver that would work better for this problem?
(Note I reduced poison's ratio of lower crust to 0.45)

Less importantly: the material spacialdb assigned to a specific material ID
in the .cfg file is not working properly. It seems to assign given material
properties to any region somewhat arbitrarily. According to Lagrit the
material id's should be...

Material id 1: Upper crust with square "hole" in it
Material id 2: Upper crust density anomaly from z=0 to z=-4000
Material id 3: Upper crust under density anomaly from z = -4000 to z=-8000
Material id 4: Lower crust

Here is zip containing cfg that produced attached images (wallowa01.cfg).​
 Wallowa1.zip
<https://drive.google.com/file/d/0BxnRdwFIDyn5QWRhaFZtMHVBYzA/view?usp=drive_web>
​
Lots of questions here and i totally understand if you can't answer them
fully. I thank you for any amount of feedback!

Nick



On Tue, Nov 1, 2016 at 1:54 PM, Nick Wogan <nicholaswogan at gmail.com> wrote:

> Hi Charles,
>
> I really am appreciating your feedback. For the past few days I have been
> trying very hard to make an 'irregular' mesh with LaGriT, where there are
> much finer elements where the density anomaly is. LaGriT is proving to be
> somewhat difficult to use. I do not have access to Cubit or Trelis, because
> (as far as i know) those programs are only freely distributed to government
> organizations such as USGS, and I work for the University of Oregon.
>
> I just wanted to say I really appreciate your help! I will report back
> once I have managed to make a mesh using LaGriT.
>
> Cheers,
> Nick
>
> On Tue, Oct 25, 2016 at 2:10 PM, Nick Wogan <nicholaswogan at gmail.com>
> wrote:
>
>> Thank you very much for the feedback,
>>
>> Attached is config/mesh/spacialdb file, and an image that provides a
>> cross-section of the model giving material properties. I am using unusual
>> material properties. Large parts of the model are youngs mod = 0.1 and
>> Poisson's Ratio = 0.49
>>
>> The problem is as follows. There is an upper crust that has typical
>> elastic material properties, and a lower crust that has young's mod = 0.1
>> and Poisson's Ratio = 0.49. In the center top of the upper crust there is a
>> small chunk of low density. The displacement output looks great, only the
>> stress output looks checkered in certain areas.
>>
>> I checked the quality of the mesh. Here is the Lagrit output:
>>
>> epsilon1, epsilonaspect: 4.6113656E-11  9.8059273E-32
>> elements with aspect ratio < .01:                      0
>> elements with aspect ratio b/w .01 and .02:      0
>> ...
>> elements with aspect ration b/w .2 and .5 :       0
>> elements with aspect ratio b/w .5 and 1. :         314844
>> min aspect ratio = 0.3795E+00     max aspect ratio = 0.7107E+00
>>
>> Thanks you again,
>> Nick
>>
>>
>> ​
>>  Checkered.zip
>> <https://drive.google.com/file/d/0BxnRdwFIDyn5U01aZEYzUURrSzg/view?usp=drive_web>
>> ​
>>
>> On Wed, Oct 19, 2016 at 4:40 PM, Nick Wogan <nicholaswogan at gmail.com>
>> wrote:
>>
>>> Hi Pylith,
>>>
>>> I am having issues with the Pylith output lacking smoothness. It is very
>>> clear in the attached photo plotting stress_zz that there are large jumps
>>> in stress that are unexpected. Is this "checker-boarding" something that
>>> can be fixed?
>>>
>>> Let me know if I should send the mesh, cfg, spacialdb files.
>>>
>>> Thanks!
>>>
>>> Nick Wogan
>>> Research Assistant
>>> University of Oregon
>>>
>>
>>
>
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