[mesa-users] Too much mesh points: SOLVED

[Ehsan Moravveji]

Dear Francis, Rob and Pablo,

Thanks for your valuable inputs. I took your hints, and inspected every mesh refinement option I had put in, till I found the “guilty”   ;-)
I realised that commenting out the following “experimental” feature avoids the blast of mesh points:

         ! Mesh function to enhance resolution near convective boundaries
         ! including regions that are newly nonconvective because of moving boundary.
         ! EXPERIMENTAL

      convective_bdy_weight = 0
      convective_bdy_dq_limit = 1d-4
      convective_bdy_min_dt_yrs = 1d-3

So, I can live happily with the rest of meshing options, and the number of mesh points stays around what I desire.

Best regards,
Ehsan.


> On 06 Aug 2016, at 03:10, Pablo Marchant <pamarca at gmail.com> wrote:
> 
> One thing that happens if an important composition jump appears, is that MESA will increase the resolution at that point all the way to min_dq_for_xa = 1d-14. I think for almost any situation this could be overkill, so it could be an additional place to relax the mesh controls.
> 
> On Fri, Aug 5, 2016 at 7:09 PM, Robert Farmer <rjfarmer at asu.edu <mailto:rjfarmer at asu.edu>> wrote:
> > I need around 3,000 mesh points across my model. For that purpose, I customise the mesh distribution, and put quite some weight around the convective and overshooting boundaries. That is when the problems begin, as soon as the mu-gradient layers develop.
> 
> Can you not just weaken your re-meshing controls then? Or do you really need the resolution in those regions and would be happy to have less resolution away from the convection/overshoot boundaries?
> 
> Rob 
> 
> On Fri, Aug 5, 2016 at 8:00 AM, Francis Timmes <fxt44 at mac.com <mailto:fxt44 at mac.com>> wrote:
> hi ehsan,
> 
> as an experiment try setting max_dq = 1/(desired number of cells)
> and removing all the customized fine-grain mesh controls being set.
> does this run to completion?
> 
> fxt
> 
> 
> 
> 
> > On Aug 5, 2016, at 3:07 AM, Ehsan Moravveji <e.moravveji at gmail.com <mailto:e.moravveji at gmail.com>> wrote:
> >
> > Dear MESA users,
> >
> > I would like to share an issue I’m facing (excessive number of mesh points), and ask for your inputs.
> >
> > I’m setting up an inlist to compute models from 1.5 Msun to 35 Msun, for later seismic modelling. Life goes pretty happy in the “lower” end, while on the “upper” end, some of my models fail due to the number of mesh exceeding the limit max_allowed_nz=20,000. This happens after ~370 steps, when centre_h1~0.69.
> > I have attached my inlist (v.8845) for a 35Msun model, with exponential overshoot f=0.04, and min_D_mix=1d9. This is an extreme case, I know; but, once this case is solved, the more relaxed cases will hopefully work too.
> >
> > The point is: if I stick to the default mesh adjustment, the evolution proceeds with ~950 mesh points, without buttlenecks. However, this is too poor resolution for calling GYRE afterwards. I need around 3,000 mesh points across my model. For that purpose, I customise the mesh distribution, and put quite some weight around the convective and overshooting boundaries. That is when the problems begin, as soon as the mu-gradient layers develop.
> >
> > My “bucket list”, here, is slim: I “wish” experimenting with high mass models, including intensive mixing, and having reasonable number of mesh points.
> > Do you have suggestions how to reach that in one go?  ;-)
> >
> > Best regards,
> > Ehsan.
> > <M35.inlist>
> >
> > <stdout.png>
> >
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> -- 
> Pablo Marchant Campos
> M.Sc on Astrophysics, Universidad Católica de Chile
> PhD student, Argelander-Institut für Astronomie


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