[mesa-users] Overshooting

[Kevin Moore]

Are you adjusting your time step using max_years_for_timestep? If so, then that will not necessarily make mesa’s time-stepping more accurate. You’ll want to look at varcontrol_target (http://mesa.sourceforge.net/controls_defaults.html#timestep_controls) for temporal resolution and mesh_delta_coeff (http://mesa.sourceforge.net/controls_defaults.html#mesh_adjustment) for spatial resolution.

-Kevin

On Jun 2, 2015, at 8:34 AM, Kenny Van <kvan at ualberta.ca> wrote:

> Hi, I was trying to produce some results using overshooting and it seems as though regardless of timestep the plot produced doesn't seem very good. I have attached the three plots I created using my data. The overshooting and changes in timestep are said in the title. But just in case I will list all the properties of the star.
> 
> &star_job
>   
>     mesa_dir = '/home/kvan/mesa_svn'
>   
>     create_pre_main_sequence_model = .true.
> 
> / !end of star_job namelist
> 
> 
> &controls
> 
> ! initial parameter
>   
>   ! initial mass of star
>     initial_mass = 20.0
> 
>   ! initial metallicity of star, MESA only goes from 0 to 0.04
>     initial_z = 0.014
> 
>   ! initial helium mass fraction of star
>     initial_y = 0.266
> 
>   ! changing the MLT to match that in Meynet
>     mixing_length_alpha = 1.6
> 
> ! overshooting
> 
>   ! all exponential overshooting is by default zero
>   ! setting step overshooting
>     step_overshoot_f_above_burn_h = 0.1
>     overshoot_f0_above_burn_h = 0.1
>     step_overshoot_f_below_burn_h = 0.1
>     overshoot_f0_below_burn_h = 0.1
>     step_overshoot_f_above_burn_he = 0.1
>     overshoot_f0_above_burn_he = 0.1
>     step_overshoot_f_below_burn_he = 0.1
>     overshoot_f0_below_burn_he = 0.1
>     step_overshoot_f_above_burn_z = 0.1
>     overshoot_f0_above_burn_z = 0.1
>     step_overshoot_f_below_burn_z = 0.1
>     overshoot_f0_below_burn_z = 0.1
> 
> ! Mass loss
>   
>   ! Changing mass loss so system acts like that of Ekstrom et al.
>   ! Use Vink mass loss rate
>     RGB_wind_scheme = 'Vink'
>     Vink_wind_eta = 1
> 
> ! timestep limits
>   ! Limit magnitude of max change in log10 total pressure in any cell
>     delta_lgP_limit = 0.2
> 
>   ! Limit magnitude of max change in log10 temperature in any cell
>     delta_lgT_limit = 0.2
> 
> ! when to stop
> 
>   ! max timestep size
>     max_years_for_timestep = 500
> 
>   ! stop when we reach AGB to produce similar results to Maynet et al.
>     stop_at_TP = .true.
> 
>   ! max age
>     max_age = 1.0d10
> 
> / ! end of controls namelist
> <20M_Low_Lim_noOS_5d5.png><20M_Low_Lim_OS_5d5.png><20M_Low_Lim_OS_500.png>
> 
> Thanks
> ------------------------------------------------------------------------------
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