[mesa-users] Fwd: New approx21 in MESA

[Manos Chatzopoulos]

Hi Bill,

  Thanks - that's very useful. So basically just use

  ! high center T limit to avoid negative mass fractions
          sig_min_factor_for_high_Tcenter = 0.01
           ! inactive when >= 1d0
             ! if Tcenter >= Tcenter_min_for_sig_min_factor_full_on,
             ! then okay to reduce sig by as much as this factor
             ! as needed to prevent causing negative abundances
          Tcenter_min_for_sig_min_factor_full_on = 2d9
             ! if Tcenter >= this, factor = 
sig_min_factor_for_neg_abundances
             ! this should be > Tcenter_max_for_sig_min_factor_full_off.
          Tcenter_max_for_sig_min_factor_full_off = 1d9
             ! if Tcenter <= this, factor = 1, so has no effect
             ! this should be < Tcenter_min_for_sig_min_factor_full_on.
          ! for T > full_off and < full_on, factor changes linearly with 
Tcenter

in my inlist exactly as you indicated in your last e-mail.

Best,

Manos
> Damn --- last second screwup in my previous message. I got ahead of 
> myself in the last comment.   We DO still need the limits on mixing at 
> high T.   I'm looking at getting rid of that requirement and my 
> fingers wrote that we'd already reached that goal.  not yet.
>
> So we no longer need the limits on reaction rates at high T but we do 
> need the limits on mixing.
>
> Hope that helps.
>
> -B
>
>
> Begin forwarded message:
>
>> *From: *Bill Paxton <paxton at kitp.ucsb.edu <mailto:paxton at kitp.ucsb.edu>>
>> *Date: *June 18, 2014 1:34:23 PM PDT
>> *To: *Manos Chatzopoulos <manolis at flash.uchicago.edu 
>> <mailto:manolis at flash.uchicago.edu>>
>> *Cc: *mesa-users at lists.sourceforge.net 
>> <mailto:mesa-users at lists.sourceforge.net>
>> *Subject: **Re: [mesa-users] New approx21 in MESA*
>>
>>
>> On Jun 18, 2014, at 12:58 PM, Manos Chatzopoulos wrote:
>>
>>> Dear all,
>>>
>>>  In the last release it was indicated that:
>>>
>>> "re implement approx21 for better performance and numerical stability
>>> using Frank's code as basis.
>>> introduce quad precision calculation of dydt"
>>>
>>>  So, in principle just calling the star_job option
>>>
>>> new_net_name = 'approx21.net'
>>>
>>>  Will automatically allow the newly implemented and improved version of
>>> the approx21 network to run right? Nothing
>>> else special flag options need to be turned on?
>>
>> Correct.
>>
>>
>>>
>>>  Is that supposed to enhance numerical performance toward the very late
>>> stages of stellar evolution (past core Si/S burning?)
>>
>> Note the following from release message:
>>
>> Begin forwarded message:
>>
>>> reimplement approx21 for better performance and numerical stability 
>>> using Frank's code as basis.
>>> introduce quad precision calculation of dydt
>>>
>>> remove high T reaction rate limits.
>>> can now run fully coupled approx21 models to core collapse without it.
>>> but note that we still have high T limits on convective coeffs
>>
>> The star test suite cases that run approx21 models to core collapse 
>> are no longer using T limits.
>> I'm working on the issue of limits on mixing at high T.
>> These were turned on by the following lines in 
>> inlist_massive_defaults; we no longer need them.
>>
>>          ! high center T limit to avoid negative mass fractions
>>          sig_min_factor_for_high_Tcenter = 0.01
>>           ! inactive when >= 1d0
>>             ! if Tcenter >= Tcenter_min_for_sig_min_factor_full_on,
>>             ! then okay to reduce sig by as much as this factor
>>             ! as needed to prevent causing negative abundances
>>          Tcenter_min_for_sig_min_factor_full_on = 2d9
>>             ! if Tcenter >= this, factor = 
>> sig_min_factor_for_neg_abundances
>>             ! this should be > Tcenter_max_for_sig_min_factor_full_off.
>>          Tcenter_max_for_sig_min_factor_full_off = 1d9
>>             ! if Tcenter <= this, factor = 1, so has no effect
>>             ! this should be < Tcenter_min_for_sig_min_factor_full_on.
>>          ! for T > full_off and < full_on, factor changes linearly 
>> with Tcenter
>>
>>
>>
>> -Bill
>>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20140618/3088a726/attachment.html>