[aspect-devel] Temperature mesh refinement criteria

[FELIPE ORELLANA ROVIROSA]

 Hi John and Rene,

       Thanks a lot for your attention.

       Yes, I got the point of the criterion for temperature-based error
minimization, as the error of the method is proportional to the second
spatial derivatives. Wolfgang sent me some relevant info.

       A lot more clear now.

thank you guys.

have a good weekend.
Felipe



On Fri, Jul 7, 2017 at 10:36 AM, John Naliboff <jbnaliboff at ucdavis.edu>
wrote:

> Hi Felipe,
>
> The mesh-refinement is based on the temperature gradients (more
> specifically, the second derivatives).
>
> From the original ASPECT paper (Kronbichler et al. 2012, GJI) is the
> following statement regarding temperature-based AMR (see section 3.2.1):
>
> "Finally, we dynamically adapt the mesh every few time steps and we need a
> criterion to decide which cells to refine or coarsen. Since the variable
> that is most indicative of abruptly changing features of the solution is
> the temperature, we apply a criterion to the temperature that is commonly
> referred to as the ‘Kelly error indicator’ (Gago et al.
> 1983) and that computes for each cell an approximation of the size of the
> second derivatives times the diameter of the cell."
>
> Perhaps some details of the exact approach of have changed since then, but
> I believe this is still the general approach for temperature and most of
> the other refinement criterion.
>
> Cheers,
> John
>
> *************************************************
> John Naliboff
> Assistant Project Scientist, CIG
> Earth & Planetary Sciences Dept., UC Davis
>
> On 07/07/2017 12:08 AM, FELIPE ORELLANA ROVIROSA wrote:
>
>
>  Hello,
>
>         I am doing 3D convection simulations, and finally I have
> implemented temperature- and strain-rate- based mesh refinement criteria. I
> tried each one of them and also the merge (hybrid) combination of them.
>
>         After some tests, for my particular problem, I have found better
> results with the sole temperature-based mesh refinement criterion. But,
> using this sole T-criterion in lieu of an hybrid T-StrRt, suggests optimal
> solution of the energy (temperature) equation, and not of the Momentum
> equation (which would be taken care by the StrainRate criterion). I now
> both equations are coupled, and perhaps more so in my case where my
> viscosity is temperature dependent, but I have my queries:
>
>         Is the temperature-based mesh refinement criterion refining the
> mesh solely according to the temperature itself?
>    or,
>         to the temperature and the temperature gradients?
>
> hope you guys can help me,
> cheers,
> Felipe
>
>
>
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