[Mesa-users] a problem of the relaxation

[曾耀田]

2020-06-07 17:52:11"曾耀田" <zengyaotian at ynao.ac.cn>写道：

Dear all,




I'm sorry to bother you, but for some reason the information in this letter is missing. I am new to MESA. I am trying to relax a model of a 1.5 solar mass star based on the result (final.mod) of 1.5M_with_diffusion in test_suite directory. To do this, as same as the example ofrelax_composition_j_entropy in the test_suite directory, I try to relax composition and entropy (but using get_entropy_for_relax_from_eos = ‘eosDT', see details below). It can run some steps but always ended with the error of dt < min_timestep_limit. I have tried to set different values for the comments in the inlist (shown below) but failed (e.g. changing the values of min_timestep_limit to 1d-30). I don't understand that even the input model has exactly the same entropy, density, and temperature profiles as the 1.5 solar mass star already had, the relaxation still doesn't work. So I try to understand the meaning of adjusting the values of these commands through the .defults file but I still don't have a clue. Now I am unsure of how and what parameters to adjust. Any ideas, suggestions, or help would be greatly appreciated!

! inlist to relax a star

&star_job

set_initial_dt = .true.
years_for_initial_dt = 1d-8

show_log_description_at_start = .false.
show_net_species_info = .true.

set_initial_cumulative_energy_error = .true.
new_cumulative_energy_error = 0d0

! Relaxes composition and entropy

relax_initial_entropy = .true.
relax_entropy_filename = 'pre-relaxed_D_T.dat'
get_entropy_for_relax_from_eos = 'eosDT'
timescale_for_relax_entropy = 1d-8 ! in years
max_dt_for_relax_entropy = 5d-6 ! in years
num_timescales_for_relax_entropy = 300

relax_initial_composition = .true.
relax_composition_filename = 'pre-relaxed_X.dat'
num_steps_to_relax_composition = 100
timescale_for_relax_composition = 1d-6

save_model_when_terminate = .true.
save_model_filename = 'relaxed.mod'
required_termination_code_string = 'max_model_number'

/ !end of star_job namelist


&controls


use_gold_tolerances = .true.

use_dedt_form_of_energy_eqn = .false.

! min_T_for_acceleration_limited_conv_velocity = 0

! check for retries and backups as part of test_suite
max_number_backups = -1
max_number_retries = 2000
max_model_number = 10000

retry_limit = 500

initial_mass = 1.5d0
varcontrol_target = 2d-4
max_years_for_timestep = 1d-2
min_timestep_limit = 1d-20

use_Type2_opacities = .true.
Zbase = 0.02

photo_directory = 'photos-relaxed'
log_directory = 'LOGS-relaxed'

profile_interval = 1
history_interval = 1
terminal_interval = 1
write_header_frequency = 10
max_num_profile_models = 10000

/ ! end of controls namelist


&pgstar

/ ! end of pgstar namelist






>>>> your operating system (including version information)

Linux version 2.6.32-220.el6.x86_64 (mockbuild at x86-004.build.bos.redhat.com) (gcc version 4.4.5 20110214 (Red Hat 4.4.5-6) (GCC) ) #1 SMP Wed Nov 9 08:03:13 EST 2011

>>>> which version of MESA you are using

mesa-r12778

>>>> which version of the MESA SDK you are using

mesasdk-x86_64-linux-20.3.1








Best wishes
Yaotian Zeng








祝好！

曾耀田
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