[CIG-SHORT] Initial stresses for large model

[Matthew Knepley]

On Thu, Jan 26, 2017 at 12:14 PM, Demian Gomez <demiang at gmail.com> wrote:

> Matt,
>
> There is no projection involved in my approach. I didn't follow Brad's
> suggestion of using a topocentric coordinate system. I have a spherical
> model constructed in a geocentric CS (ECEF) and my initial stress spatial
> database in lat lon depth (i.e. cs-data = geographic and is-geocentric =
> false). Therefore, the conversion from one type of coordinate to the other
> shouldn't have any effect.
>

Projection is a mathematical term, meaning an operator P such that P^2 = P.
When you represent a function in
another space, this is a projection.

  Matt


> Demián
>
> On Wed, Jan 25, 2017 at 9:26 PM, Matthew Knepley <knepley at rice.edu> wrote:
>
>> On Wed, Jan 25, 2017 at 6:55 PM, Demian Gomez <demiang at gmail.com> wrote:
>>
>>> Dear all,
>>>
>>> A few months ago I asked a question about strategies to assign the
>>> initial stresses for a large model. I was originally using a SimpleDB file
>>> and Brad suggested that a SimpleDbGrid provides a much faster
>>> interpolation. Here's the thread: http://lists.geodynami
>>> cs.org/pipermail/cig-short/2016-November/002612.html
>>>
>>> I am now calculating the initial stresses on a first run (as explained
>>> here: https://wiki.geodynamics.org/_media/software:pylith:tu
>>> torials:cdm2016:pylithtutorial2016_gravity.pdf) and I want to use them
>>> to compute quasi-static co-seismic deformation. I've looked
>>> at generate_statedb.py in the gravity examples, which uses a SimpleDB file
>>> to input the stresses into Pylith. This method, however, will generate a
>>> severe slow down, as discussed in the previous thread.
>>>
>>> Is there another strategy to input the initial stresses calculated by
>>> the first Pylith run? I do not want to use a SimpleGridDb because this will
>>> require two interpolations: a first one to generate the grid and a second
>>> one to assign the stresses to each cell. I'm afraid this will lead to
>>> slightly unbalanced stresses generated by the two interpolations.
>>>
>>
>> The projection should be idempotent. Once you project the first time, you
>> have done the damage.
>>
>>  Matt
>>
>>
>>> Thanks,
>>> Demián
>>>
>>> --
>>> *Dr. Demián D. Gómez*
>>> Postdoctoral Researcher
>>> The Ohio State University - School of Earth Sciences
>>> 275 Mendenhall Laboratory
>>> 125 South Oval Mall
>>> Columbus, Ohio 43210
>>> Cell: +1 (901) 900-7324 <(901)%20900-7324>
>>> email: gomez.124 at osu.edu
>>>
>>>
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>>>
>>
>>
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