[CIG-SHORT] Gravity on GeoLocalCart System

[Brad Aagaard]

Cecep,

Thanks for pointing out the mention of the use_gravity parameter in the 
manual. It appears that we overlooked updating that section of the 
manual some time ago when we changed the gravity settings. The examples 
are correct in that you turn on gravity using

gravity_field = spatialdata.spatialdb.GravityField

I have started to look into more thorough testing of the gravity field 
with an Earth-centered Earth-fixed (ECEF) coordinate system. So far 
everything looks correct.

You say that you got an "unrealistic" result when you used gravity. In 
looking at your output I see large displacements, primarily in the 
vertical direction. I can't tell if anything is incorrect based on just 
the output you provided. The large displacement are expected unless you 
use initial stresses equal to the overburden pressure. See the gravity 
examples in the manual for a discussion of this issue.

Regards,
Brad


On 08/01/2016 03:22 PM, Cecep Pratama wrote:
> Dear Brad,
>
> I use pylith to simulate the static simulation with prescribed slip
> on buried fault plane. I made 3D mesh based on Earth-centered,
> earth-fixed coordinate system. However, I got unrealistic result when
> compare the simulation result with and without gravity feature. I am
> not sure if my gravity setting goes wrong or not, but I only set the
> gravity using default setting. I attached the result and cfg file
> (wgravity = with gravity, wogravity = without gravity). I also
> attached the error.log in one of the folder when I tried to turn on
> gravity using
>
> use_gravity = true
>
> as written at 6.5 section on the manual. So, I changed with
>
> gravity_field = spatialdata.spatialdb.GravityField
>
> and I could not understand the result since it produce unrealistic
> large displacement than if I turned off the gravity setting.
>
> Please kindly advise if there is something wrong with my setting and
> cfg file.
>
> Thank you
>
> Regards, Cecep
>