[Mesa-users] hot accretion and spiky luminosity

[Thomas Steindl]

Hi Bill,

Thank you for the quick response!
Sure,  I will run some tests and see at which point the trouble starts. I will come back to you as soon as I have some results!

Thomas

> Am 27.05.2020 um 17:56 schrieb Bill Paxton <paxton at kitp.ucsb.edu>:
> 
> you can help me on this by finding the smallest extra heat that works well.  then we can increment from there to see what breaks.  that approach to debugging works better for me than starting from something badly broken and trying to make sense of the rubble.
> 
> b
> 
> 
>> On May 27, 2020, at 8:27 AM, Bill Paxton <paxton at kitp.ucsb.edu <mailto:paxton at kitp.ucsb.edu>> wrote:
>> 
>> retract that — i looked more closely at your run_star_extras routine.  since the extra_heat you are adding doesn’t depend on the cell variables such as T or rho, you don’t need to use the implicit form.
>> 
>> this one will take some time.  i’ll put it on my to-do list, but perhaps someone else will be able to help sooner.
>> 
>> good luck,
>> b
>> 
>>> On May 27, 2020, at 7:52 AM, Bill Paxton <paxton at kitp.ucsb.edu <mailto:paxton at kitp.ucsb.edu>> wrote:
>>> 
>>> Hi Thomas,
>>> 
>>> 1st thing to try is to replace your use of other_energy by other_energy_implicit.  That allows the extra heat to be calculated on each newton iteration and provides the necessary partials of the heat to guide the solver.
>>> 
>>> -B
>>> 
>>> 
>>>> On May 27, 2020, at 4:36 AM, Steindl, Thomas <Thomas.Steindl at uibk.ac.at <mailto:Thomas.Steindl at uibk.ac.at>> wrote:
>>>> 
>>>> Hello all,
>>>> 
>>>> I am trying to calculate models of accreting protostars with accretion rates up to 1d-4 M_sun/yr and hot accretion, where the energy is put into the outer layers of star only (typically outer 10% of the radius).  I have tested different methods to put in the extra heat but I decided to use the method which is available on the marketplace (http://cococubed.asu.edu/mesa_market/inlists.html <http://cococubed.asu.edu/mesa_market/inlists.html>, Michael Kuffmeier) for this thread. In essence, a lot of material is accreted onto the star which leads to extra heat in the surface area.
>>>> However, I am having the problem that in the zones below the injection of the extra heat, the luminosity becomes very spiky and the solver is having trouble with convergence. This spikes appear rather random to me and change size and form with almost every timestep. I attach a work directory (latest MESA version) to this mail in order for you to reproduce the problem. This includes pgstar inlist that will show the luminosity profile. The calculations are rather lengthy, therefore i include a model after 400 steps, for you to see the problem immediately if you want. I do not include the star executable as this has ~50mb.
>>>> In this case, the extra_heat is put in at a constant level, leading to a jump in extra heat. I have experimented with multiple other ways to put in the extra heat (e.g. in a tanh shape to not have any jumps) but the problem persists.
>>>> 
>>>> Do any of you have any idea concerning what causes this spikes and how I can help MESA with the convergence?
>>>> As always, I am happy for any input. Thank you very much in advance!
>>>> 
>>>> Thomas
>>>> 
>>>> __________________________________________________________________
>>>> Thomas Steindl, MSc
>>>> University of Innsbruck | Institute for Astro- and Particle Physics
>>>> Tel: +43 512507 52031
>>>> Mail: thomas.steindl at uibk.ac.at <mailto:thomas.steindl at uibk.ac.at>
>>>> <work_mailing.zip>_______________________________________________
>>>> mesa-users at lists.mesastar.org <mailto:mesa-users at lists.mesastar.org>
>>>> https://lists.mesastar.org/mailman/listinfo/mesa-users <https://lists.mesastar.org/mailman/listinfo/mesa-users>
>> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200527/9152d51a/attachment.htm>