[Mesa-users] Producing a medium to high mass pure Helium star

[Josiah Schwab]

Hi Charlie,


> I did take a look at the 'time step controls' in controls.defaults, but
> the terminal error I am typically getting is 'max increase' and this output
> isn't mentioned anywhere in controls.defaults so I am not sure what would
> be the suitable parameter to change. Do you know what this refers to?
>

That message appears when the timestep is increasing (and the per-step
increase is limited by max_timestep_factor).  Usually what is actually
keeping the timestep small is some sort of solver failure that periodically
drives the timestep down via a series of retries.  Then the timestep creeps
back up (the phase with the max increase messages), but the solver starts
failing again and forces it back down, etc.  So in that case, 'max
increase' won't tell you much about what's going on, but understanding why
the timestep repeatedly gets driven back down will be marginally more
informative.

I don't have time to look at your model today, but I can at least pass
along some sympathy. I know this to be a tricky and challenging (and
frustrating) regime of evolution.

Josiah
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