[Users] ML_ADMQuantities question

Wolfgang Kastaun physik at fangwolg.de
Tue Apr 3 17:06:43 CDT 2018

On 04/03/2018 09:54 PM, Erik Schnetter wrote:
> Wolfgang
> I don't think such a thing exists.
> It should be relatively straightforward to calculated the ADM
> quantities from the ADM variables. I also think this is how it should
> be done; I was surprised to see that it is done differently. After
> all, that's why we have the ADM variables -- as lingua franca so that
> thorns don't have too many interdependencies.

Such a thorn would be nice. However, if there is a good reason to
directly use the evolved variables in the BSSN system, it would still be
nice to add a CCZ4 version for completeness. I guess it should be easy
since Z4 and BSSN are fairly similar.

> Do you need the ADM integrands everywhere or just on a 2-sphere? If
> the latter, then the thorn QuasiLocalMeasures could provide these.

I wanted to have some fun with the actual integrants in 3D. For 2D
surface integrals, QLM indeed works just fine for me.

@Roland: In the interface.ccl of ML_ADMConstraints I only see the ADM
constraints, no expressions for ADM energy and angular momentum. Or did
you mean something else?


> -erik
> On Tue, Apr 3, 2018 at 9:05 AM, Wolfgang Kastaun <physik at fangwolg.de> wrote:
>> Hi,
>> I just started using the ML_ADMQuantities thorn (because I wanted the
>> ADM integrants, not just the integrals), and stumbled on two issues:
>> 1. It seems this thorn only works with ML_BSSN, is there a version for
>> ML_CCZ4 somewhere?
>> 2. Madm and Jadm3 are declared as tensorweight=0 in the interface.ccl,
>> but it seems to me that they already include the square root of the
>> 3-metric determinant (at least I got the correct ADM mass by just using
>> the standard average reduction operator on them for some test). Should
>> that be tensorweight=1 instead?
>> Cheers,
>> Wolfgang.
>> _______________________________________________
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