[aspect-devel] AGU meeting feedback

[Wolfgang Bangerth]

On 12/31/2013 08:50 AM, Timo Heister wrote:
> Okay, sometimes it helps to look at the output:
> http://i.imgur.com/0o9ojFa.png
> these are two runs, on the left with 5 global refinements and 6 on the right.
>
> So, not only does the second peak occur at a different time, it is a
> plume that rises from a different location (see t=600).
>
> Why does this happen? It looks like the plume on the left comes from
> the first staircase (on the right) in the initial condition. Now it
> makes sense that the solution is dependent on the mesh size. We
> obviously do a poor job with a good initial condition for the
> compositional field.

These are very interesting observations. Thanks for looking into this.

But this begs other questions:

- First, what do the codes used in van Keken do? Do they actually use
   discontinuous initial fields? I don't have the paper here with me and,
   in addition, do not know what the codes in question do. Does someone
   know?

- Second, what happens if we use a smooth field, say using an arctangent
   with a width of 2-3 cells. I bet that the first peak is exactly where
   it was before, whereas the second one suddenly becomes grid independent.

Best
  Wolfgang


-- 
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Wolfgang Bangerth               email:            bangerth at math.tamu.edu
                                 www: http://www.math.tamu.edu/~bangerth/