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.
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.
Do you need the ADM integrands everywhere or just on a 2-sphere? If the latter, then the thorn QuasiLocalMeasures could provide these.
-erik
On Tue, Apr 3, 2018 at 9:05 AM, Wolfgang Kastaun physik@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:
- It seems this thorn only works with ML_BSSN, is there a version for
ML_CCZ4 somewhere?
- 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.
Users mailing list Users@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users
Hello all,
there is, as far as I remember, not having looked at their code at all, ML_ADMConstraints that computes the constraints based on the ADM variables (even though it is in the ML repo). Not sure if there are grid functions that match what you are looking for though.
Yours, Roland
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.
Do you need the ADM integrands everywhere or just on a 2-sphere? If the latter, then the thorn QuasiLocalMeasures could provide these.
-erik
On Tue, Apr 3, 2018 at 9:05 AM, Wolfgang Kastaun physik@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:
- It seems this thorn only works with ML_BSSN, is there a version
for ML_CCZ4 somewhere?
- 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.
Users mailing list Users@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users
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?
Cheers, Wolfgang.
-erik
On Tue, Apr 3, 2018 at 9:05 AM, Wolfgang Kastaun physik@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:
- It seems this thorn only works with ML_BSSN, is there a version for
ML_CCZ4 somewhere?
- 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.
Users mailing list Users@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users
Hello Wolfgang,
@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?
I meant ML_ADMConstraint but did not check its interface.ccl. If they are not there then I have no better suggestion than Erik. Are the changes from BSSN to ccZ4 or Z4c more than just "replace K with K+X"?
Yours, Roland
On 04/04/2018 01:14 AM, Roland Haas wrote:
Hello Wolfgang,
@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?
I meant ML_ADMConstraint but did not check its interface.ccl. If they are not there then I have no better suggestion than Erik. Are the changes from BSSN to ccZ4 or Z4c more than just "replace K with K+X"?
As far as I remember, the BSSN variables are also present in the CCZ4 system, with differences only in the case of constraint violating states.
Yours, Roland
As written, thorn ML_ADMQuantities requires another thorn with the name ML_BSSN to be present.
-erik
On Wed, Apr 4, 2018 at 7:52 AM, Wolfgang Kastaun physik@fangwolg.de wrote:
On 04/04/2018 01:14 AM, Roland Haas wrote:
Hello Wolfgang,
@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?
I meant ML_ADMConstraint but did not check its interface.ccl. If they are not there then I have no better suggestion than Erik. Are the changes from BSSN to ccZ4 or Z4c more than just "replace K with K+X"?
As far as I remember, the BSSN variables are also present in the CCZ4 system, with differences only in the case of constraint violating states.
Yours, Roland
The way I would remedy the situation is:
- look at the Mathematica source file for thorn ML_ADMQuantities - remove the declaration of the external ML_BSSN variables - peek at thorn ML_BSSN to find how these are defined in terms of the ADM variables, and insert this definition where needed, e.g. calculating det g from g_ij instead of from W
For someone familiar with Kranc that should be straightforward, and not more difficult than creating a second version that attaches itself to ML_CCZ4.
-erik
On Wed, Apr 4, 2018 at 8:53 AM, Erik Schnetter schnetter@cct.lsu.edu wrote:
As written, thorn ML_ADMQuantities requires another thorn with the name ML_BSSN to be present.
-erik
On Wed, Apr 4, 2018 at 7:52 AM, Wolfgang Kastaun physik@fangwolg.de wrote:
On 04/04/2018 01:14 AM, Roland Haas wrote:
Hello Wolfgang,
@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?
I meant ML_ADMConstraint but did not check its interface.ccl. If they are not there then I have no better suggestion than Erik. Are the changes from BSSN to ccZ4 or Z4c more than just "replace K with K+X"?
As far as I remember, the BSSN variables are also present in the CCZ4 system, with differences only in the case of constraint violating states.
Yours, Roland
-- Erik Schnetter schnetter@cct.lsu.edu http://www.perimeterinstitute.ca/personal/eschnetter/
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