[CIG-LONG] Negative Pressures in Gale

[Mark Fleharty]

On Sat, Feb 23, 2008 at 6:23 PM, Walter Landry <walter at geodynamics.org> wrote:
> "Mark Fleharty" <mark.fleharty at gmail.com> wrote:
>  > This produces an output.extension directory that has a lot of various
>  > data, 500 time steps in all.  Looking through the pressure*.vtk files
>  > I can verify that I have negative numbers, but I'm not sure what this
>  > means.  I also notice them when I view them with paraview.  I've
>  > attached an image file demonstrating the problem.
>
>  Negative pressure means that the element is undergoing an expansive,
>  rather than compressive stress.  It is expected for that setup.
>  The hydrostatic pressure, especially near the top, is rather small.
>  Thus, any dynamic pressure easily overcomes the hydrostatic pressure.

Ok, great, thanks that helps a lot.

>  > Also, does anyone have any tips on how to create St.Germain input XML
>  > files.  I've looked through the documentation as best I can, and I
>  > think I'm confused about some of the basics.  Is there any other
>  > documentation available on St. Germain outside of Gale that people
>  > could recommend?
>
>  There is the documentation for Underworld at
>
>   http://www.mcc.monash.edu.au/Software/UnderworldModels
>
>  Gale is mostly the same underlying software, although not entirely the
>  same.  So the models probably won't work out of the box, but they may
>  give you a better idea of how to create models.

Great.  Thanks, this appears to be useful.

Thanks,

Mark