[Users] Carpet: Domain specification fails

[Ian Hinder]

On 14 Dec 2015, at 17:14, dumsani <g14n8326 at campus.ru.ac.za> wrote:

> Hi All,
> 
> I am working with some piece of code based on a multipatch coordinate system
> (llama, http://dx.doi.org/10.1103/PhysRevD.83.044045). Currently, I'm interested
> in doing a test in a cubical kind of domain, that is, without the multipatch system.
> Closely following the qc0-mclachlan.par parameter file (ET_2014_05), I converted
> my multipatch parameter file to use the following:
> Carpet::domain_from_multipatch          = "no"
> Carpet::domain_from_coordbase         = yes
> CartGrid3D::type                        = "coordbase"
> 
> Unlike when using a multipatch sysytem, I've had to add the ReflectionSymmetry
> thorn in my thornlist for running on a cubical grid. The simulation is able to build
> successfully. But when running, it breaks with the following error from Carpet:
> cactus/arrangements/Carpet/Carpet/src/SetupGH.cc:1744: void Carpet::get_domain_specification(const cGH*, int, const ivect&, rvect&, rvect&, rvect&): Assertion `not CCTK_IsFunctionAliased ("MultiPatch_GetDomainSpecification")' failed.
> 
> Looking at the function that fails and a few ideas I got from the user mailing list, my naive
> thought is that this might possibly be an issue of cctk_lsh vs cctk_ash in Carpet.
> (e.g. http://lists.einsteintoolkit.org/pipermail/users/2014-October/003849.html). But I'm yet
> to test this idea. The code I'm working with uses cctk_lsh.
> 
> I would gladly appreciate help from anyone who could have an idea about this.
> 
> I'm using ET_2014_05 release of the EinsteinToolkit/Cactus. I have attached my test
> parameter file for viewing in case it will be useful in diagnosing the problem(s).
> 
> Thank you in advance for your kind assistance.

Hi Dumsani,

The relevant lines in Carpet, in SetupGH.c/get_domain_specification, require that if you set domain_from_coordbase, then you must not have the function MultiPatch_GetDomainSpecification available in an active thorn.  In other words, you can't activate a thorn which provides multipatch at the same time as getting the domain from CoordBase.  You have the Coordinates thorn active, which provides multipatch (or more specifically, it provides the aliased function MultiPatch_GetDomainSpecification), hence this error.  You will need to remove Coordinates from your ActiveThorns.  

At that point, it's possible that CTGamma will complain, because I think it requires some basic multipatch functionality.  The thorn CTGamma/CartesianCoordinates is provided for this case, so if you run into problems after deactivating Coordinates, try activating CartesianCoordinates.

I attach an old parameter file which uses CTGamma on a Cartesian grid.  I have not run this with the current version of the code, but it used to work at some point!

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