[mesa-users] Diffusion of Heavy elements (Instability in some evolution tracks)

[Nsamba Benard]

Hello Aaron,

Thank you.

Cheers,
Nsamba

----------------------------------------------------------------------------------------------------------
Benard Nsamba
PhD student                                  Centro de Astrofisica
                                                    Universidade do Porto
                                                    Rua das Estrelas
Tel: +351 920 404 108                   4150-762 Porto, Portugal
E-mail: benard.nsamba at astro.up.pt <Benard.Nsamba at astro.up.pt>
Skype: benardnsamba

On Mon, Jan 23, 2017 at 4:59 PM, Aaron Dotter <aaron.dotter at gmail.com>
wrote:

> Hi Nsamba,
>
> I have had success in avoiding this sort of behavior by setting
>
>       diffusion_min_dq_at_surface = 1d-3
>
> in your the controls section of your inlist.  It defaults to a much
> smaller number (1d-9).
>
> In my case, the issue is that a small cell at the surface may fluctuate
> back and forth between Z>0 and Z=0.  Requiring this cell to be larger stops
> this from happening.
>
>
> Aaron
>
>
>
>
>
>
> On Mon, Jan 23, 2017 at 10:13 AM, Nsamba Benard <
> nsambabenard2net at gmail.com> wrote:
>
>> Greetings to You all,
>>
>> I am making a grid of models with diffusion included using mesa-r7624. In
>> some of my models, the evolution track has some instabilities (fast
>> variation in temperature and luminosity) as shown in the attached plot.
>>
>> However, when I consider diffusion of only Hydrogen and Helium, the model
>> track is good (plot attached).
>>
>> I would like to know what is causing this instability when diffusion of
>> heavier elements is included (this happens to some models)? Any suggestions
>> on how to fix this problem? I have also attached my inlists.
>>
>> Thank you.
>>
>> Cheers,
>> Benard
>>
>>
>> ------------------------------------------------------------
>> ----------------------------------------------
>> Benard Nsamba
>> PhD student                                  Centro de Astrofisica
>>                                                     Universidade do Porto
>>                                                     Rua das Estrelas
>> Tel: +351 920 404 108 <+351%20920%20404%20108>
>> 4150-762 Porto, Portugal
>> E-mail: benard.nsamba at astro.up.pt <Benard.Nsamba at astro.up.pt>
>> Skype: benardnsamba
>>
>> ------------------------------------------------------------
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>>
>
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