[CIG-SHORT] Varying material properties in 3D

[Charles Williams]

Dear Michal,

I haven’t looked at your mesh, but the 3D linear interpolation is not quite as simple as specifying values at the corners of the cube.  You probably need to provide more points where the values are known, probably on the faces of the cube.  Because of roundoff, it may also be necessary to provide values that are slightly outside the cube.  I’m afraid you will need to experiment a bit.

Cheers,
Charles



> On 28/03/2015, at 6:43 pm, Michal Dichter <mdichter at unm.edu> 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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Charles A. Williams
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