[Mesa-users] do_solve_diffusion FAILED

[Cao, Kaili]

Hi Evan,

Thank you for your reply. I intended to make more accurate predictions on the first dredge-up, i.e., the surface C and N abundance. Earlier today, my advisor told me that the signal of diffusion in the outer layers will be erased on the RGB, hence I decided not to include the element diffusion in my following simulations. Nevertheless, I really appreciate that you told me why diffusion doesn't work.

Cheers,
Kaili
________________________________
From: Evan Bauer <evan.bauer.astro at gmail.com>
Sent: Wednesday, July 13, 2022 11:50 AM
To: Cao, Kaili <cao.1191 at buckeyemail.osu.edu>
Cc: mesa-users <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] do_solve_diffusion FAILED

Hi Kaili, Diffusion is probably more difficult in this model because it has a radiative envelope instead of a convective envelope like the sun. This can make it difficult for diffusion to operate near the surface, and you may see that metals

Hi Kaili,

Diffusion is probably more difficult in this model because it has a radiative envelope instead of a convective envelope like the sun. This can make it difficult for diffusion to operate near the surface, and you may see that metals sink away from the photosphere very quickly.

What effects of diffusion do you want to focus on for this model?

Cheers,
Evan

On Jul 12, 2022, at 8:03 PM, Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>> wrote:

Dear MESA Users,

Thank you for reading this email.

I am trying to evolve a M = 2.2 M⊙ model from the beginning to past the RGB bump. However, during the main sequence evolution, I repeatedly got "do_solve_diffusion FAILED" messages, and the simulation went very slowly.

More specifically, I started to get this message since step 747; when I interrupted the program after step 2390, I got 330 "do_solve_diffusion FAILED" messages in total. For your reference, the age_yrs at step 740 was 2.5720E+08, that at step 750 was 2.8098E+08, and that at step 2390 was 6.4468E+08.

This behavior is not expected, because when I use exactly the same numerical and physical settings to evolve an M = 1.0 M⊙model, everything goes smoothly; there are no "do_solve_diffusion FAILED" messages.

One clue I got by perusing the terminal output is that, for the M = 2.2 M⊙ model, MESA is writing a large number of opacity cache files like:
write $MESA_DIR/data/kap_data/cache/OP_gs98_z0.0**_x0.**.bin
but it does not write any such files for the M = 1.0 M⊙ model.

I have no idea why this happens. Could you please provide me with some hints about this? The inlists and terminal output for the M = 2.2 M⊙ model are attached to this email. Thank you for your time and I look forward to your response.

Best regards,
Kaili Cao
<2.2M_He_core_0.40M_nohup.out><inlist_start><inlist_to_past_rgb_bump>_______________________________________________
mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>
https://lists.mesastar.org/mailman/listinfo/mesa-users<https://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!KGKeukY!3sShGQGIZUQN6BXZS9VLjPuLZWTfZjXhJoymDxxzf2Vjm1lsbCZqGRgtUaN8NEecgZ8HXvhS4bk_jO4tZiyfGolMTUhEI9i_SHy0QSA$>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20220713/7beac786/attachment.htm>