On Thu, Sep 22, 2016 at 08:14:42PM -0500, Roland Haas wrote:
I am wondering if there would be anything wrong with running ML_ADMConstraints with just a single time level for the constraints as well as using no SYNCs for it as long as I set it's calc_every parameter to the frequency of the coarsest level.
Obviously this will give my "nonssense" values in the ghost zones, buffer zones and boundary (though on the boudary I can just set it to zero).
However since the constraints are pure output and nothing ever depends on them the bad values only matter if they were to eg show up in the norms. It is my recollection that CarpetReduce actually does not use any values from the ghost zones (certainly that would be wrong) or buffer zones (this may be more recent).
Is there any any other way the "bad" values could make it into the norms? Note that I do not worry about 1d, 2d, 3d output for the constraints.
I think this should be fine, provided you not only set calc_every to your coarse step, but also your output frequency for the norms (or adjust your post-processing for that). The former shouldn't even be necessary, but why would you calculate them more often then you output them...
Frank