[Users] new evolution_methods "frozen-ID" and "regrid-only" for ADMBase

[Roland Haas]

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Hello all,

this is related to ticket 1399 on trac
(https://trac.einsteintoolkit.org/ticket/1399).

There it is proposed to introduce new evolution methods to ADMBase
that are intended to be used for simulations where the spacetime
metric is either time independent (eg when using a fixed background
spacetime for hydro simulations) or can be computed analytically at
each step.

Currently the "static" evolution method in ADMBase will apply boundary
conditions as well as prolongation after each step which can be
undesirable if the analytic spacetime is known since prolongation will
change the values in the buffer zones.

The two new methods would would do the following:

regrid-only:
* never apply boundary conditions, never do a SYNC
* after a regrid (in the postregrid routine) re-apply the initial
condition by scheduling ADMBase's initial data group

apply-ID:
* never apply boundary conditions, never do a SYNC
* schedule ADMBase's initial data group before each timestep

The later (apply-ID) is very similar to using Exact's "exact"
evolution method while the first one is more economical in that it
only re-computes the spacetime when required (assuming a time
independent spacetime).

The two changes would allow to use any ID thorn (as long as it only
sets the current timelevel) as a source for a background spacetime.

This email is to query for "nicer" names for the two methods.

Currently proposed are "regrid-only" for the method that does
"reapply-initial-condition-after-grid-structure-changes" and
"apply-ID" for "reapply-initial-condition-at-every-time-step".

I'll apply the patch sometime after next week with the then current
winning name choice.

Yours,
Roland

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