[mesa-users] mass loss, rotation, binaries, and a hydrodynamic surface boundary conditions

[David Arnett]

OK Tomasz, maybe we should be explicit. It would be useful for people who
are using approximate methods to know the cause of errors.

First, what worries you about the equations? We can write them out
generally in an inertial frame in 3D; conservation of mass, momentum and
energy, with radiative transfer and MHD. We just can't solve them
accurately. Are you thinking of something else?

Second, what is wrong with the methods? My favorite worry is that a grid
code will have errors because the fluid sweeps through the mesh rapidly,
and an SPH code, which can move with the matter, will have resolution too
low to represent turbulence. I suppose the issue is a general one with
zoning for high Reynolds number and optically thick-thin plasmas.

What are your favorites?

Dave

On Wed, Jun 17, 2015 at 11:39 AM, Tomasz Plewa <tomekplewa at gmail.com> wrote:

>  No. There is no code in existence that could solve this problem in 3D,
> regardless computational resources. The problem is with equations, then
> with methods, and perhaps only then with the available computing power.
>
> Tomek
> --
>
> On 06/17/15 10:44, David Arnett wrote:
>
>  Hmmm.  It sounds like a problem that can be done, but probably not with
> sufficient resolution to be believed in detail, unfortunately. Maybe when
> Moore's law has more time to help us.
>  Dave
>
> On Tue, Jun 16, 2015 at 11:55 PM, Pablo Marchant <pamarca at gmail.com>
> wrote:
>
>> There is a big uncertainty in accretion when you reach critical rotation.
>> Whether or not the material gets ejected, and how much angular momentum it
>> would carry with it has a very large impact on the final fates of several
>> binary systems. 3D simulations would certainly be enlightening here, but my
>> experience on 3D hydro is definitely insufficient to attempt this on my own.
>>
>> On Mon, Jun 15, 2015 at 9:19 PM, David Arnett <wdarnett at gmail.com> wrote:
>>
>>> This sounds interesting. It seems that you are exploring a region of
>>> parameter space in which some of our approximations need to be merged into
>>> a more wholistic formulation. We encounter the same sort of issue when we
>>> simulate turbulent convection near a boundary in a star. When the flow is
>>> no longer radial, interesting new things may happen. We should look for
>>> instances in which the purely 1D representation needs more careful thought,
>>> and maybe 3D simulation "spot checks" for guidance.
>>>
>>> --
>>> David Arnett
>>> Regents Professor
>>> Steward Observatory
>>> University of Arizona
>>>
>>> Facts are stubborn, but statistics are more pliable.  Mark Twain
>>> Facts do not cease to exist because they are ignored.  Aldous Huxley
>>>
>>
>>
>>
>>   --
>> Pablo Marchant Campos
>> M.Sc on Astrophysics, Universidad Católica de Chile
>> PhD student, Argelander-Institut für Astronomie
>>
>
>
>
> --
> David Arnett
> Regents Professor
> Steward Observatory
> University of Arizona
>
> Facts are stubborn, but statistics are more pliable.  Mark Twain
> Facts do not cease to exist because they are ignored.  Aldous Huxley
>
>
> ------------------------------------------------------------------------------
>
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-- 
David Arnett
Regents Professor
Steward Observatory
University of Arizona

Facts are stubborn, but statistics are more pliable.  Mark Twain
Facts do not cease to exist because they are ignored.  Aldous Huxley
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