[CIG-SHORT] Varying material properties in 3D

[Brad Aagaard]

Michal,

SimpleDB is best for scattered points. It attempts to form a tetrahedron 
using the points around the query location. It can use scattered points 
but it is not very robust, especially for points on a sparse regular 
grid. It works much better for scattered points with a spacing similar 
to that of the underlying mesh.

If your points are on a logically rectangular grid, then SimpleGridDB is 
much more efficient (much faster queries) and robust. See Section 4.5.3 
in the PyLith manual. The file format is given in Appendix C.3.

Regards,
Brad

On 03/27/2015 10:43 PM, Michal Dichter wrote:
>
> Dear PyLith gurus,
>
>
> I have a hollow magma chamber embedded in a three-dimensional
> cubical domain and I want to spatially vary the Vs values in three
> dimensions. My tetrahedral mesh (.exo attached) is 250x250x100 km
> and consists of 3 materials (all elastic for now). The elements are
> all well-formed.
>
>
> I have successfully used the SimpleDB structure to vary Vs along a
> line and on a plane (use mat_elastic_2D.spatialdb and see the
> statevar output for mu). However PyLith always returns an error
> whenever I try to vary Vs over the full volume: "Could not find
> parameters for physical properties at (x,y,z)." I am confounded by
> the error because I set a Vs value at each of the 8 corners of the
> cubical domain (mat_elastic_3D.spatialdb). I wonder why PyLith runs
> for 1D and 2D but not for 3D? PyLith actually runs the 3D case when
> I use query_type = nearest. However I would much prefer to use
> query_type = linear for my problem.
>
>
> Do you know where I have gone wrong? Or what I have not understood
> about the SimpleDB structure? Or maybe there is something funny
> about my mesh because of the hollow magma chamber? Thanks for your
> help! I look forward to your reply.
>
>
> Best,
>
>
> Michal
>
>
> ____________ Michal Dichter Department of Physics and Astronomy
> University of New Mexico (860) 459-0956
>
>
>
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