[Users] ADMConstraints

[Erik Schnetter]

While calculating the constraints with ADMConstraints in the presence  
of mesh refinement works fine, there was a problem with calculating  
norms of the constraints, which may require time interpolation.  In  
order to do this correctly, it is necessary to keep several time  
levels of the constraints, and to re-calculate the constraints after  
changing the grid hierarchy.  If this is not done, then the values of  
the constraints at each output grid point are correct, but norms of  
the constraints may not be.

I updated ADMConstraints so that it supports this behaviour.  In  
order to remain backward compatible, this behaviour cannot be the  
default.  Obtaining correct norms for the constraints requires  
setting the parameters

ADMConstraints::constraints_persist = yes
ADMConstraints::constraints_timelevels = 3

where the number 3 depend on the time interpolation order; for linear  
time interpolation, you only need 2 time levels.

On the other hand, if you want to save space and time, and if you do  
not need the norms of the constraints, then you should set the parameter

ADMConstraints::constraints_prolongation_type = "none"

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>

My email is as private as my paper mail.  I therefore support encrypting
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