[Users] Carpet: How to turn off auto-prolongation for 'mesh-refinement ghosts'?

[Ian Hinder]

On 21 Nov 2012, at 16:03, Scott Hawley <scott.hawley at belmont.edu> wrote:

> My thorn BruiserSetBG saves a background spacetime which is then used by
> the solver thorn BruiserConstraints.
> 
> The background is set via an analytic expression, even in the regions
> designated as ghost zones.  The ones I'm concerned about in this e-mail
> are not inter-processor ghost zones, rather they are regions which (for
> all OTHER gridfunctions) are typically filled in via prolongation from a
> coarser grid.
> 
> But for the background, I don't want this prolongation to occur, and it's
> happening automatically without my specifying to do so.
> 
> BrusierSetBG is created in local mode, thus I'm not explicitly calling any
> sync operation, but the ghost info is getting overwritten before the data
> makes it to BrusierConstraints.  Presumably this sync is being called
> inside the flesh/scheduler.    BruiserConstraints is a global thorn.
> 
> Question:  Is there any way to specify that, for a particular set of grid
> functions (i.e. the background spacetime), no prolongation is to occur?  I
> haven't seen a parameter that does this.

You can set the tag prolongation="none" in the interface.ccl entry for that group.

e.g.

arrangements/Carpet/Carpet/interface.ccl:

CCTK_INT point_classification TYPE=gf TAGS='checkpoint="no" prolongation="none"'


> I am open to re-writing BrusierSetBG as a 'global' thorn if that will make
> a difference.   Otherwise perhaps I'll create a thorn called "BrusierBoth"
> or something, that feeds the background straight into the solver.
> 
> Thanks very much,
> Scott
> 
> 
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-- 
Ian Hinder
http://numrel.aei.mpg.de/people/hinder