[Mesa-users] Question about the PPISN test suite

[Jeremy Sakstein]

Hi Rob,

I have a quick follow up question about this.

I ran some more checks and it turns out that the two runs aren't just
nearly identical, all of the physics parameters are 100% identical. As far
as I can tell, the only difference is in log_rel_run_E_err, which is a
little higher (roughly +1) when the lines above are commented out.

I took this to mean that these energy checks are not limiting any of the
time steps but I do not really understand what this log_rel_run_E_err so I
wanted to check to see if this interpretation is indeed correct before I
consider the matter closed?

Cheers,

Jeremy

On Mon, Jul 6, 2020 at 12:08 PM Jeremy Sakstein <sakstein at hawaii.edu> wrote:

> Thanks Rob,
>
> I tested this by commenting those lines out and rerunning a grid. I indeed
> find that the runtime increases dramatically but the final results seem to
> be identical.
>
> Cheers,
>
> Jeremy
>
> On Fri, Jul 3, 2020 at 3:07 AM Rob Farmer <r.j.farmer at uva.nl> wrote:
>
>> Hi,
>> The implications are what is stated in the comments, this allows larger
>> timesteps during core he burning. You should run your own tests to see if
>> this makes a difference for your results (there are many ways to get longer
>> timesteps during the evolution, some are more useful than others).
>>
>> The test suite isn't designed to give the most physical results possible,
>> simply something reasonable within a limited amount of runtime (so that we
>> can run the tests quickly).
>>
>> This goes for all test cases, they should only be a starting point as you
>> need to experiment yourself with the options and controls it uses to decide
>> which options work/don't work for your science case.
>>
>> Rob
>>
>>
>> On Thu, 2 Jul 2020 at 00:56, Jeremy Sakstein <sakstein at hawaii.edu> wrote:
>>
>>> Hi everyone,
>>>
>>> I have a question about the PPISN test suite. I was looking at
>>> run_star_extras.f and found the following lines:
>>>
>>>          ! Ignore energy checks before first time hydro is turned on
>>>          ! otherwise need small steps during core helium burning and it
>>>          ! slows down the test_suite
>>>          if (.not. s% lxtra(lx_hydro_has_been_on)) then
>>>             s% cumulative_work_outward_at_surface = 0d0
>>>             s% cumulative_work_inward_at_center = 0d0
>>>             s% cumulative_eps_grav = 0d0
>>>             s% cumulative_delta_total_energy = 0d0
>>>             s% cumulative_energy_error = 0d0
>>>             s% cumulative_L_center = 0d0
>>>             s% cumulative_L_surf = 0d0
>>>             s% cumulative_extra_heating = 0d0
>>>             s% cumulative_irradiation_heating = 0d0
>>>             s% cumulative_Ne22_sedimentation_heating = 0d0
>>>             s% cumulative_nuclear_heating = 0d0
>>>             s% cumulative_non_nuc_neu_cooling = 0d0
>>>             s% cumulative_sources_and_sinks = 0d0
>>>             write(*,*) &
>>>                "Setting energy conservation error to zero until hydro is
>>> turned on for the first time"
>>>          end if
>>>
>>> From what I can tell, this is essentially turning energy conservation
>>> checks off. I wanted to know what the implications of this are?
>>>
>>> Would one expect dramatically different results e.g. final black hole
>>> mass, mass at helium depletion if one were to comment these lines out?
>>>
>>> Cheers,
>>>
>>> Jeremy
>>>
>>
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