[Users] McLachlan crash

Wed Feb 27 10:11:35 CST 2013

Vassilli

This lapse minimum looks strange. During evolution, if there is a puncture,
the lapse minimum should be much smaller than 0.4.

Of course, in the end (when the lapse minimum becomes negative), things go
wrong. You could set McLachlan's parameter to enforce a positive lapse,
e.g. enforcing that the lapse does not go below 10^-10.

-erik

On Wed, Feb 27, 2013 at 11:01 AM, Vassilios Mewes <vassilios.mewes at uv.es>wrote:

> hello Erik,
>
> i have attached a plot of the minimum value of the lapse vs time....
>
> here is the segment of the par file where i set the dissipation:
>
> Dissipation::order = 5
> Dissipation::vars = "
>         ML_BSSN::ML_log_confac
>         ML_BSSN::ML_metric
> ML_BSSN::ML_trace_curv
>         ML_BSSN::ML_curv
>         ML_BSSN::ML_Gamma
>         ML_BSSN::ML_lapse
>         ML_BSSN::ML_shift
>   ML_BSSN::ML_dtlapse
>         ML_BSSN::ML_dtshift
> "
>
> best wishes,
>
> Vassili
>
>
> On Wed, Feb 27, 2013 at 4:45 PM, Erik Schnetter <schnetter at cct.lsu.edu>wrote:
>
>> 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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>>>> and signing email messages. Get my PGP key from http://keys.gnupg.net.
>>>>
>>>>
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>>>
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>>
>>
>> --
>> Erik Schnetter <schnetter at cct.lsu.edu>
>> http://www.perimeterinstitute.ca/personal/eschnetter/
>>
>
>

-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/
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