[CIG-SHORT] Inconsistency Between Linear and Powerlaw Viscoelastic Gravitational Forces

[Brad Aagaard]

Jeff-

Can you explain more specifically what differences you see in the 
stresses? Please specify if this occurs for the elastic solution (first 
time step) or at latter time steps. Is the displacement field the same 
but only the stress fields are different? Are the strains different or 
just the stresses?

When I use the pylith trunk, I get identical deformation (displacements, 
strains, and stresses) for the elastic solution, but then the 
deformation (all fields) seem to differ between the two problems.

Another issue to keep in mind is that the physical properties as well as 
the initial state variables must be equivalent for the deformation to be 
the same.

Charles- Is there anything tricky about differences in the state 
variables between the MaxwellIsotropic3D model and the PowerLaw3D model 
that could be responsible for this issue.

Brad


On 10/12/2010 01:58 PM, Jeffrey Thompson wrote:
> Dear CIG Developers,
>
> I've been running into difficulties with the magnitude of gravitational
> stresses using a PowerLaw3D rheology.  As a consistency check, I ran two
> models with the same material parameters, using a MaxwellIsotropic3D
> rheology first and a PowerLaw3D rheology (with n=1) second.  I obtained
> wildly different values of stress within the two model runs, with the
> magnitudes of stresses varying by about 10 orders of magnitude.  I've
> attached a tarball with my model parameters for both cases, and was
> wondering if you could take a look at this problem.
>
> I'm currently running PyLith 1.5.1 using the tarballed version available off
> of the CIG website (i.e. not an svn version).
>
> Thanks,
> Jeffrey Thompson
> Seismolab
> California Institute of Technology
>
>
>
>
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