[Users] Llama and Coordinates::additional_overlap_size

[Ian Hinder]

On 2 Apr 2017, at 04:29, Christian D. Ott <cott at tapir.caltech.edu> wrote:

> Hi All,
> 
> I've been playing around with the GW150914 par file and have been trying 
> to set up a pure Cartesian AMR run with the exact same grid setup in the 
> Cartesian region.
> 
> I noticed that
> 
> Coordinates::additional_overlap_size    = 3
> 
> (that appears to be required) not just increases the size of the 
> cubed-sphere patches, but also of all patches in the Cartesian region, 
> including refined regions. Is this a feature (if so, why?) or a bug?

Hi Christian,

I have never noticed this; I hope it's not happening, as it would be very strange!  If it is happening, it definitely sounds like a bug.  I'm fairly sure I have checked the refined regions in the past when using Llama, and they were the expected sizes.  So if this is happening now, it is likely a change (probably to Carpet) that has happened relatively recently (the past year or two).

Can you post the parameter files and carpet-grid.asc files for the two runs which differ only in additional_overlap_size?

Is it possible that by increasing additional_overlap_size, the coarsest Cartesian grid RL0 is being moved inwards too close to the buffer zones of RL1, and RL1 is being extended to cover RL0 as a result?  This would result in RL1 appearing to increase in size, but it shouldn't affect the finer levels.  Do you see the finer levels also change?

-- 
Ian Hinder
http://members.aei.mpg.de/ianhin

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