# [CIG-SHORT] comment on resolution of benchmark problems

Tue Jul 18 13:20:14 PDT 2006

```Carl-

Charles already constructed uniform meshes for both the reverse and
strike-slip cases at resolutions of 1000m, 500m, and 250m. Charles
plans to look at your strike-slip meshes and compare them to his. At
this point, PyLith is hogging memory and the 500m resolution is about
the max doable. Hopefully this will change in the next week and the
250m resolution will be possible.

For variable resolution, the goal is to achieve a more accurate
solution using a variable resolution with the same number of nodes as
the uniform resolutions.

On Tuesday 18 July 2006 1:04 pm, Carl W. Gable wrote:
> I'd like some feedback on what type of mesh
> size is going to be realistic for the benchmark
> calculations. The definition talks about using
> 125m resolution if possible. Uniform elements
> will require about 42,000,000 elements for that
> resolution.
>
> A back of the envelope calculation shows that
> for the strike slip and reverse fault problem
> you have a fault that is a plane apx. 16km x 16km.
> If you line just the face of the fault with 125m
> spaced nodes, and then also put a plane of nodes
> of the same resolution above and below the fault
> you have:
>
> 16*8*16*8 = 16,384 nodes for a single plane.
>
> For three planes of nodes you have:
> 49152 nodes.
>
> If you connect those up to form tetrahedra
> you will get about 2*6*49152 = 589,826 tets
> just to mesh the fault plane.
>
> So even with an adaptive strategy to only
> refine the fault the number of elements is
> going to hit 1,000,000 very quickly. Is
> this going to be realistic for computations?
>
> Even the regular mesh calculations will have:
> (the factor for number of elements is between 5-6)
>
> 1000m resolution =>    24*24*24*6 =    82944 elements
>  500m resolution =>    48*48*48*6 =   663552 elements
>  250m resolution =>    96*96*96*6 =  5308416 elements
>  125m resolution => 192*192*192*6 = 42467328 elements
>
>
> Carl
>
>
> ----------------------------------
> Dr. Carl W. Gable, Staff Scientist
>
> Voice 505-665-3533 Fax   505-665-8737
> Email gable at lanl.gov
> http://www.ees.lanl.gov/staff/gable
>
> EES-6, MS T003
> Los Alamos National Laboratory
> Los Alamos NM 87545
>
> Hydrology, Geochemistry & Geology Group (EES-6)
> Focus: Geophysics, Hydrology, Mesh Generation
> Correspondence / TSPA
> ----------------------------------
>
>
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```