[mesa-users] Mass Transfer + Rotation Problems

[Pablo Marchant]

The saved model I sent you has not actually been affected by the donor at
this point, so this should be just due to the single star evolution.

Just to check, I just run the accretor as a single star, using the attached
inlist. I save model 63 which is about the same age as the previous model I
sent you. Then loaded that model with the same inlist, but specifying a
mass_change, and problems arise... Using a mass_change of about 9.8d-6 i
can get a couple of steps to converge before getting the tiny timesteps.
Though, I can't seem to find the same pressure inversion you mention,
neither before nor after I set mass_change...

I'll keep checking and tell you if I find something else.

Cheers!


On Sun, Mar 3, 2013 at 7:28 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:

> Hi Pablo,
>
> I notice that the model you sent is already in trouble even before the
> convergence fails.
> There is a pressure inversion in the outermost 2 grid points.   The 1st
> couple of steps
> converge in spite of this, but then remesh adds a bunch of points at the
> surface and
> that seems to be enough to push things over the edge.  The many retries
> and small
> timesteps are an attempt to deal with the pressure inversion (I think).
>
> It may well be a problem in the mass accretion that has led to the P
> inversion, but
> we'll need to go back to an early model to see it happen.
>
> Cole, as a work around, turn off velocities.  That seems to be all it
> takes.
> Let me know it that works for you.
>
> Cheers,
> Bill
>
>
>
>
>
>
> On Mar 3, 2013, at 8:05 AM, Pablo Marchant wrote:
>
> Ok, saved a model of the accretor for the binary run, just before mass
> transfer, to experiment with it with single star mesa.
>
> Attached is the model star with the inlist I'm using to test it. For
> mass_change = 1d-5 the model has problems converging and ends up with very
> small timesteps right away. Slightly smaller mass_change can cause the
> model to behave at the first timesteps, but end up in the same situation.
>
> Just to note, this also seems to happen with mass loss, though things
> start getting messy at around mass_change = -1d-4.
>
> The value 1d-5 is actually around the same value that the implicit scheme
> attempts before ending up with tiny timesteps, and it's not very high, I
> would actually expect it to rise significantly more than that.
>
> I'm certainly interested in digging into the mass adjustment routines and
> how it deals with angular momentum, as I'm starting to check how to
> implement the missing features regarding rotation into binary MESA.
>
> Cheers!
>
>
> On Fri, Mar 1, 2013 at 6:38 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:
>
>> Hi Pablo,
>>
>> On Mar 1, 2013, at 5:53 AM, Pablo Marchant wrote:
>>
>> > Will try to see if I can get something similar experimenting with
>> single rotating stars to check if this is effectively not a problem with
>> the rlo routines.
>>
>> Thanks for looking into this.
>> If it turns out not to depend on the rlo routines, feel free to punt it
>> back to me.
>> But if you'd like to dig into the details of the interactions of rotation
>> and
>> mass transfer, I'd be delighted.  ;-)
>>
>> It is quite possible that this is the first case of accreting onto a
>> rotating model.
>> The case of mass loss with rotation has been run alot, but not mass gain.
>>
>> Cheers,
>> Bill
>>
>>
>
>
> --
> Pablo Marchant Campos
> M.Sc on Astrophysics, Universidad Católica de Chile
> PhD student, Argelander-Institut für Astronomie
>  <accretor_rotating.dat><inlist>
>
>
>


-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD student, Argelander-Institut für Astronomie
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