[mesa-users] Convergence problem with rotating very massive model

[Bill Paxton]

You need to evolve to near zams before turning on rotation.
i.e., have an initial inlist that creates the pre-ms model without rotation
and then let's it evolve until it is near zams.  a simple stopping test for this is

         Lnuc_div_L_upper_limit = 1

save the final model when it reaches near zams

         save_model_when_terminate = .true.
         save_model_filename = 'wr_1.mod'

Now in a second inlist, load your saved model
   
   load_saved_model = .true.
   saved_model_name = 'wr_1.mod' 

turn on rotation and make any other changes you'd like.  e.g.,
(you can specify initial rotational velocity or as surface omega/omega_crit)
            
      change_rotation_flag = .true. 
      new_rotation_flag = .true. 
            
      set_initial_omega_div_omega_crit = .true.
      new_omega_div_omega_crit = 0.3
      set_omega_div_omega_crit_step_limit = 10
         ! if model_number is <= this limit, then at end of step set uniform omega 
         ! to give surface omega/omega_crit = new_omega_div_omega_crit

      set_initial_age = .true.
      initial_age = 0 ! in years

      set_initial_model_number = .true.
      initial_model_number = 0

      set_initial_dt = .true.
      years_for_initial_dt = 10
      

That should get you to where you can run the massive rotating model from zams.

But keep in mind that massive stars rotating near critical are an area
of active development in mesa --- (translation: we don't really know
how to make them work yet!) 

Good luck,
Bill







On Sep 8, 2012, at 6:14 AM, Ehsan Moravveji wrote:

> Hello all,
> I would like to check if a Galactic massive star, at say 60 Msun, can
> reach the Wolf-Rayet phase. The purpose is to see if MESA can reproduce
> results of Georgy et al. (2012, A&A); initially, their Figure 1.
> The attached inlist tries to make the initialization as close as possible
> to Georgy et al.
> For this, I did ./rn and it gives a convergence error:
> 
>        mdot rotation_enhancement factor    2.8840315031266050D+09   
> 1.0000000000000000D+00
>    1st model retry: new log10 dt/secyer   -6.5000000000000000D+00
> retry
>        mdot rotation_enhancement factor    2.8840315031266050D+09   
> 1.0000000000000000D+00
> retry
>        mdot rotation_enhancement factor    2.8840315031266050D+09   
> 1.0000000000000000D+00
>    1st model retry: new log10 dt/secyer   -8.8010299956639813D+00
> retry
>        mdot rotation_enhancement factor    2.8840315031266050D+09   
> 1.0000000000000000D+00
> retry
>        mdot rotation_enhancement factor    2.8840315031266050D+09   
> 1.0000000000000000D+00
>    1st model retry: new log10 dt/secyer   -1.1704119982655925D+01
> retry
>        mdot rotation_enhancement factor    2.8840315031266050D+09   
> 1.0000000000000000D+00
> 
> stopping because of convergence problems -- too many backups
> 
> 
> 
> 
> terminated evolution: convergence problems
> 
>          1   6.161591   4682.697 -10.932952 -10.932952  60.000000 
> 60.000000   0.720000   0.000706   0.266000   0.720000 -12.031373
>   966      3
>  -Infinity  -3.914618   2.622773 -99.000000 -12.330820 -99.000000  
> 0.000000   0.266000   0.006552   0.014000   0.266000   0.008964     14  
>   2
> 0.0000E+00  10.546468   5.203662 -99.000000   2.781446  -8.702539  
> 0.000000   0.002409   0.001470  1.400E-02  1.
> 
> I have to mention that this does NOT occur with non-rotating models.
> How can I trace back this problem?
> I run SDK-type MESA v.4236 with OMP_NUM_THREADS=3, on a Mac.
> 
> Thanks for your concern.
> Ehsan.
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