[Mesa-users] About noises in the mass transfer rate curve

[Pablo Marchant]

Hi Xiang, please include mesa-users in these emails.

I have to say that I have no simple solution for this issue, at the late
stages of mass transfer the radius is very sensitive to the mass transfer
rate, and can result in these numerical issues.  You can see that the
change in radius when you have that noise in mass transfer rate is
associated to noise in the stellar radius of less than 0.1%. You could try
reducing the value of implicit_scheme_tolerance, though at 1d-4 I'm still
seeing plenty of noise.

Despite this, you can see there is a consistent behavior in the mass
transfer rate, and in particular many people doing calculations very
similar to this average the mass transfer rate through multiple steps in
order to plot their results.

The main thing you need to be concerned with is convergence. As you use
smaller timesteps and higher resolution I'm pretty sure you'll see your
results are consistent, despite the presence of that noise. Unless there is
a fundamental reason for you to make that curve continuous, I would not
spent too much time on it.

Cheers

On Tue, Aug 22, 2017 at 1:40 AM, 贺祥 <hexiang at ynao.ac.cn> wrote:

> Dear professor  Pablo Marchant,
>     Recently , I tried to use MESA to compute the evolution of binary
> stars.
> I found that the mass transfer rate curve is always not smooth in my
> calculation.
> See the attached figures (1.pdf  /2.pdf/3.pdf/4.pdf).  I have tried to
> vary parameters (e.g. fm, fr) in the inlist,
> but the noise in the curve is still there. I would think the noise is due
> to some numerical reason.
> Is there anyone who can tell me how to reduce the noise in the curve and
> make the curve smooth?
> Thanks in advance!  The inlist files are attached.
>
>
> Cheers,
> Xiang He
>
>
>
>
>
>


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