[CIG-SHORT] Question regarding spatial database with depth and lateral dependent properties

[Brad Aagaard]

Josimar,

With a lateral density variation the stress field within each material 
will be close to rho*g*z (z < 0 so these values are negative, 
corresponding to compression), but there will be perturbations due to 
the density variation. You may want to start a simulation with the 
initial stresses in each material equal to rho*g*z, but you will need to 
run it for many time steps to get the viscoelastic material to relax and 
reach a steady-state solution (see examples/2d/gravity/README Step 3, 
especially gravity_isostatic.spatialdb).

Regards,
Brad


On 10/24/2016 11:51 AM, Josimar Alves da Silva wrote:
> Dear Brad,
>
> Thank you so much for the reply.
>
> Material 1 and 2 have densities that are different for each material,
> but both densities are constant throughout the domain.  Material 2,
> however, is viscoelastic. Therefore, I am trying to design the input
> file for the "out-of-plane stress component (Szz)" that is mentioned on
> page 56 of the manual.
>
> For flat layers, the input format for
>  "db_initial_state.iohandler.filename" is:
>
> X Y stress-xx  stress-yy  stress-xy  stress-zz-initial  total-strain-xx
> [ .. ]
>
> Where in most cases Sxx=Syy=Szz= rho*g*h. (as in the step 16, page 161;
>  step2 page 194 of the manual. ).
>
> For my specific geometry, since the layer thickness of both materials
> change laterally, it is unclear for me the correct order of the input
> values on the file for the initial stresses.
>
> Find attached the .cfg files that I am using as input for my specific
> geometry. Note that, for better understanding,  I refer to the material
> densities generically as rho1 and rho2 in the attached files.
>
> Do you see any problem with the order that I include the values on the
>  "mat1_initila_stresses.spatialdb" and "mat2_initila_stresses.spatialdb"
> ?. So far with these files I can't achieve static equilibrium.
>
> Thank you in advance for you time.
> Best regards,
> Josimar
>
>
>
>
>
>
>
>
>
>
>
>
> On Sun, Oct 23, 2016 at 11:20 PM, Brad Aagaard <baagaard at usgs.gov
> <mailto:baagaard at usgs.gov>> wrote:
>
>     Josimar,
>
>     See examples/2d/gravity, especially step03. For linear elasticity,
>     the setup is relatively straightforward. With viscoelastic materials
>     it can get tricky if the lateral density variation extends into the
>     viscoelastic material, because the lighter material wants to move on
>     top of the denser material.
>
>     Regards,
>     Brad
>
>
>
>     On 10/22/16 3:00 PM, Josimar Alves da Silva wrote:
>
>         Dear Pylith community,
>
>         I am new on Pylith and I am looking for an example of spatial
>         database
>         for initial stress specification.
>
>         My goal is to specify depth and lateral  dependent initial
>         stresses in
>         order to avoid initial displacements when the gravity field is
>         "turned on".
>
>         The attached figure can help. In summary my question is:
>
>         1) How to specify initial conditions for the stresses to compensate
>         gravitational displacements for the attached domain geometry ?
>
>         Note that I am able to make this work for a domain of flat
>         layers, as
>         shown in several examples in the manual, however, not for inclined
>         layers like this one.
>
>         Thank you in advance for you help,
>         Best,
>         Josimar
>
>
>
>
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