[Users] Mclachan, CCZ4: Wrong "phi" term in Ricci tensor?

Ian Hinder ian.hinder at aei.mpg.de
Mon May 21 10:58:56 CDT 2012


On 18 May 2012, at 23:43, Barry Wardell wrote:

> On Fri, May 18, 2012 at 7:28 PM, Barry Wardell <barry.wardell at gmail.com> wrote:
> On Fri, May 18, 2012 at 7:18 PM, Erik Schnetter <schnetter at cct.lsu.edu> wrote:
> The current implementation of the CCZ4 formulation in McLachlan
> contains the expression (2/phi) in the definition of R[li,lj].
> However, the meaning of phi depends on the conformalMethod, and this
> is not explicitly taken into account here. Is this wrong?
> 
> So far, the CCZ4 formulation has only been tested with the W conformal method. In principal it should work, but given that it hasn't really been tested it is possible that there are bugs. In this case, this looks like a bug to me and this term should be different if the W conformal method is not used. Given how close we are to a release, should we just add a note to the release notes (or elsewhere) stating that only the W method currently works?
> 
> Dana has said she will be able to make sure the code works for the phi conformal method, but she will be travelling for the next week so will not be able to do it until after then.

In that case, we should just modify the CCZ4 version of the code to not include the conformalMethod parameter, and substitute the equations with conformalMethod = 1, since only the value of 1 currently works.  This will avoid problems with people forgetting to set the parameter, or maybe setting it to 0 thinking that it works in the same way as ML_BSSN.

-- 
Ian Hinder
http://numrel.aei.mpg.de/people/hinder

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