[mesa-users] Is there any way to solve min_time_step convergence problem?

[Bill Paxton]

Hi,

General advice: if possible, start from a test_suite case that does something similar to what you want.  Then make small incremental changes to turn it into what you want, checking after each change to be sure it still works.

In your case you might use star/test_suite/20M_si_burn as a starting place.  Copy the inlists to a work directory.  
Edit the file 'inlist' to remove the lines
      read_extra_star_job_inlist1 = .true.
      extra_star_job_inlist1_name = '../inlist_test_suite'
and also check the path to inlist_massive_defaults 
DO NOT remove the lines to load inlist_massive_defaults --- you need that!

Do ./clean, ./mk, and ./rn to see if your copy works and evolves all the way to core collapse.

Then change the file 'inlist_si_burn' to comment out the lines
      load_saved_model = .true.
      saved_model_name = '20M_si_burn.mod'

Now try again -- it should load a zams file and evolve that to core collapse.

Finally, change the initial_mass and try that.

If that works, you might want to go back to see what is different from what you tried before that failed.
You'll learn something that might be useful!   Let us know.

Good luck,
Bill






On Oct 23, 2014, at 4:52 AM, 이현택 wrote:

> Dear MESA users,
> 
> I have faced on numerical problem during the simulation.
>  
> When I try to make an iron core for very high mass star models(40M, 45M, 50M),
>  
> it terminates with min time step convergence problem.
>  
> For 50M case, it terminates with the output message "termination code: v_surf_div_v_kh_upper_limit".
>  
> The inlist file is here(the only difference is the initial mass of the ZAMS) :
> 
> &star_job
>    create_pre_main_sequence_model = .false.
>    change_initial_net = .true.      
>    new_net_name = 'approx21.net' 
>    pgstar_flag = .true.
>  
> / !end of star_job namelist
> 
> &controls
>   ! starting specifications
>   zams_filename = 'zams_z2m2_y28.data'
>       initial_mass = 40
>       initial_z = 0.02d0
>       Zbase = 0.02d0
>  
>   okay_to_reduce_gradT_excess = .true. 
>   varcontrol_target = 1.0d-3
>   mesh_delta_coeff = 3
>   min_timestep_limit = 1d-99
>   fe_core_infall_limit = 1d8 ! cm/sec
>   mixing_length_alpha = 2
> 
>   RGB_wind_scheme = 'Dutch' !string means no RGB wind
>   AGB_wind_scheme = 'Dutch'! empty string means no AGB wind
>   RGB_to_AGB_wind_switch = 1d-4
>   Dutch_wind_eta = 1  
>  
> / ! end of controls namelist
>  
> I'm using the mesa version 6794 and mesa SDK version 20140715.
> If you have any opinion, please notice me. It would be very helpful to me.
>  
> -Sincerely yours, HYUN TAEK-
> 
> 
> 
> 
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