[Users] McLachlan constraint time levels

[Erik Schnetter]

Bruno

This depends on whether you want the mesh refinement boundaries of the
constraint variables be interpolated from the next coarser grid, or
remain undefined/set to zero. In principle, these boundaries are not
important if you are looking for 3D output, but if you want to look at
reductions then you will need time interpolation. However, this
requires in addition that the constraints be calculated at every
iteration, and is thus expensive both in terms of memory requirements
and computing time requirements. Most people are therefore fine with
undefined prolongation boundaries and only look at e.g. 1D output,
ignoring the ghost and boundary points.

-erik

On Wed, Feb 9, 2011 at 5:34 PM, Bruno Coutinho Mundim
<bcmsma at astro.rit.edu> wrote:
> Hi,
>
> I am receiving the messages of the following kind in my simulation with
> McLachlan:
>
> (line 1084 of ./Cactus/arrangements/Carpet/CarpetReduce/src/reduce.cc):
>   -> Grid function "ML_BSSN::H" has only 1 time levels on refinement
> level 0; this is not enough for time interpolation
>
> and it is indeed true that the constraint variables has 1 time level only:
>
> CTK_REAL ML_Ham type=GF timelevels=1 tags='tensortypealias="Scalar"
> tensorweight=0'
> {
>   H
> } "ML_Ham"
>
>
> I was wondering if we shouldn't be using 3 time levels instead.
>
> Thanks,
> Bruno.
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-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/