[Mesa-users] Why the results are so mesh-sensitive?

[anne.thoul at uliege.be]

Dear Matheus,

The fact that your results depend on the mesh size and timestep is a sign that your models have not reached a converged state.
You know that you have reached a converged situation if taking smaller timesteps and smaller mesh size does not change your results anymore. 
Try using a smaller maximum timestep using for example max_years_for_timestep, and smaller values of mesh_delta_coeff, until your results do not change anymore.

I hope this helps

Anne




> Le 28 juin 2018 à 21:52, Matheus Bernini via Mesa-users <mesa-users at lists.mesastar.org> a écrit :
> 
> Hello everyone!
> 
> My name is Matheus, I'm an undergraduate student. I'm using MESA (r-9575) to study the evolution of massive stars. I've noticed that the choose of spatial resolution (mesh_delta_coeff) has a strong impact on the evolution of my models. I've made tracks for one star (32M_sun, rotating, like Ekstrom+2012) using differents meshes only [ https://drive.google.com/file/d/1cK0cuhJj9MYfd8bjnbfWrrfAahzsIWZc/view?usp=sharing <https://drive.google.com/file/d/1cK0cuhJj9MYfd8bjnbfWrrfAahzsIWZc/view?usp=sharing> ]. On this diagram (Mass x LogTeff) smaller mesh_delta_coeff's make the tracks move to cooler regions (they keep evolving to LogTeff < 3.7) while larger ones make them stay on warmer temperatures. 
> 
> I'd like to know which mesh_delta_coeff I should use, and more important, how can I know (on other cases) if my spatial resolution is correct? The same for temporal resolution and mesh_delta_coeff_for high_T (although I've tested them like that).
> 
> <MassxLogTeff.png>
> 
> 
> Thanks
> 
> 
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