[mesa-users] trace the computational cell that is limiting the timestep

[Mathieu]

Hi Bill,

Many thanks for this! I'll remember to send a model next time.

Mathieu

On 04/13/2014 10:20 PM, Bill Paxton wrote:
> Hi Mathieu,
>
> 1st, thanks for sending the inlist and a photo.  Usually it is better 
> to send a saved model rather than a photo, but in this case it worked 
> fine.
>
> I made the following 3 changes in your inlist:
>
> 1)
> use approx21.net <http://approx21.net> instead of approx26.net 
> <http://approx26.net>
>
> 2)
>       mesh_delta_coeff = 3
> instead of
>       mesh_delta_coeff = 1
>
> for the late burning stages I've found that I can increase 
> mesh_delta_coeff and still have enough cells.
> in your case I'm still getting 1500+ cells even with mesh_delta_coeff = 3.
> Try the larger value while you are trying to get things to work;
> then come back and check for convergence by decreasing mesa_delta_coeff.
>
> 3)
>          varcontrol_target = 1d-2
> instead of
>          varcontrol_target = 1d-4
>
> again, like for mesh_delta_coeff, try a larger value while trying to 
> get things to work.
> then reduce it to check convergence later.
>
> with these 3 changes, I was able to restart your photo and get it to 
> go to core collapse in 247 steps in about 1.4 minutes of runtime.
>
>  runtime, prev time, retries, backups, steps         1.4         2.0   
>    9739       299    284247
>  284247  10.126392   1848.395  23.430390  24.849838  12.308650   
> 8.132779   0.000000   0.000000   0.327378 0.424153  10.954351   1538   
> 9739
>  -10.393057  10.622930   3.111692  21.739086  17.688434 -99.000000 
> 4.175871   0.000010   0.000000   0.019025   0.350215 3.580514      3   
>  299
>  1.3391E+07  28.782825   4.244046  24.832632   1.198830  -9.604670 
> 2.495086   0.000000   0.000000   0.000000  2.256E-01  0.000E+00  highT 
> del Ye
>
> Good luck!
>
> -B
>
>
>
>
>
>
>
>
> On Apr 13, 2014, at 7:46 AM, Mathieu wrote:
>
>> Hi everyone,
>>
>> I am wondering if there is a way to trace which computational cell is 
>> limiting the timestep in MESA 6208.
>>
>> I am trying to simulate a 15 solar mass star with MESA 6208 and I 
>> find extremely small timesteps during Si shell burning.
>> I know I could lower the min_timestep_limit (setting it to 10^-10 sec 
>> the run goes on), but I'd like to find why and where such small 
>> timesteps are needed.
>> I attach the inlist I am using and a photo (284000), if someone wants 
>> to reproduce the problem.
>>
>> Thanks for any suggestion,
>>
>> Mathieu
>>
>>
>> <284000><inlist_project.txt>------------------------------------------------------------------------------
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>

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