[CIG-SHORT] Meshing Schemes, Mixed Meshes, Mesh Output, & Initial Conditions

[Carl W. Gable]

http://meshing.lanl.gov/proj/crustal_dyn_strike_slip_bm/catalog.html

If anyone has the inclination to give it a try, there is a variable 
resolution tet mesh, with tets along the fault face and along the fault 
tip refined to 125 m.

To compare to the uniform tet mesh:
           1000m    500m       250m     variable
#node    15625    117649    912673    179978
# elem   82944    663552   4962216   1037548


Also, when you connect a uniform orthogonal point distribution to form 
tets, you can form 5 tets from each hex or 6 tets from each hex. Does 
that have any significant impact on the results you obtain with the 
1000m, 500m and 250m grids?

Cheers,
Carl

Brad Aagaard wrote:
> Following up on Ravi's questions and my response yesterday-
> 
> I posted the PyLith poster from the 2007 AGU Fall Meeting in my folder on the 
> CIG website (http://www.geodynamics.org/cig/Members/BradAagaard). The poster 
> includes plots of the local error in the elastic solution of the strike-slip 
> benchmark for both hex8 and tet4 cells at 1000 m, 500 m, and 250 m 
> resolutions. We also show the runtime for the serial runs (1000 m and 500 m 
> resolutions). We expect similar trends for comparison of linear (p1) quad4 
> and tri3 cells.
> 
> Note that the largest local error occurs at the edge of the taper region where 
> the slip transitions from a uniform value to a constant gradient. This causes 
> a sharp gradient in the strain field along this edge, so finer cells are 
> needed in this region to accurately capture the solution. For the rest of the 
> area where slip is uniform or has a uniform gradient (taper region), the 
> linear basis functions do quite a good job of capturing the displacement 
> field (the local error is quite small).
> 
> These results indicate that for this problem the linear (p1) hex8 cells far 
> outperform linear (p1) tet4 cells (factoring in both run time and the global 
> error). We suspect that quadratic (p2) tet4 cells will be competitive with p1 
> hex8 cells in terms of performance (comparable global error for the about the 
> same run time). We have yet to implement automatic creation of p2 cells from 
> a p1 mesh, so we have not tested this hypothesis.
> 
> Brad
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-- 

\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
Dr. Carl W. Gable, Staff Scientist
EES-6, MS T003
Los Alamos National Laboratory
Los Alamos NM 87545

gable at lanl.gov     Voice 505-665-3533     Fax   505-665-8737
http://www.ees.lanl.gov/staff/gable     http://lagrit.lanl.gov

Hydrology, Geochemistry & Geology Group (EES-6)
Focus: Geophysics, Hydrology, Mesh Generation
Correspondence / TSPA
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