[Users] McLachlan crash

[Erik Schnetter]

Vassili

In my experience, one needs to "control" the puncture by ensuring that (a)
things evolve only slowly there (keeping the lapse small) and (b) adding
sufficient dissipation.

What is the value of the lapse near the puncture?
How much dissipation are you adding?
To which variables are you adding dissipation?

-erik


On Wed, Feb 27, 2013 at 8:53 AM, Vassilios Mewes <vassilios.mewes at uv.es>wrote:

> Hello all,
>
> still no success with the full evolution of BH+torus...
>
> i have attached the par file i have been using lately, in which i added
> two more levels of mesh refinement, as Roland suggested, increased the
> Dissipation order to 5th and removed the parameter
> ML_BSSN::dt_lapse_shift_method = "noLapseShiftAdvection"..
>
> this has improved things a bit, but the L_inf norm of the hamiltonian
> constraint still starts growing at around t=200 (after having decreased and
> then having been rather constant up to that point) and then the simulation
> will crash later (either due to the shift being nan at the puncture or by
> detecting nans)
>
>
> in the meantime, i have evolved a single puncture, the bondi accretion
> onto a puncture and an "inverse cowling" (setting up the spacetime and
> hydro variables of the BH+torus system but only evolving the spacetime),
> all using the same parameters, and all of those work...its only the full
> system of BH+torus when i run into problems...this is using the ET 2012.11.
> release..
>
> do you have any ideas what might go wrong with the spacetime evolution
> when evolving the full system?
>
> best wishes,
>
> Vassili
>
>
> On Tue, Feb 12, 2013 at 2:07 AM, Roland Haas <
> roland.haas at physics.gatech.edu> wrote:
>
>> Hello Vassilios,
>>
>> > as mentioned earlier in the ET phone call, i have attached the par file
>> > used in the run...
>> >
>> > i tried checking for the nans in the output, but the last hdf5 output
>> was
>> > too many iterations earlier and they aren't visible in 1D ascii output
>> > either
>> >
>> > as said, the puncture tracker actually aborted the run, not the nan
>> > checker...
>> Thank you for the parameter file. As a unsubstantiated guess, I would
>> try what happens if you move the outer boundary further out. Right now
>> it sits at 50M which I would find uncomfortably close if there is any
>> say "junk" radiation (eg from setting up a BH with spin in flat
>> background) present. I'd move it to at least 200M (ie two more levels of
>> mesh refinement). Not sure how likely this explanation is since your
>> NaNs appear after many (9) light crossing times.
>>
>> Yours,
>> Roland
>>
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-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/
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