[mesa-users] Increase resolution in surface ionization zones?

[Bill Paxton]

Hi Zhao,

Take a look at the section in star/defaults/controls.defaults under the heading "mesh adjustment".

In particular, check this one:

         ! T_function2 = T_function2_weight*log10(T / (T + T_function2_param))
   		T_function2_weight = 0
   		T_function2_param = 2d4 
   		   ! largest change in T_function2 happens around this temperature
   		   ! default value puts this in the envelope ionization region.

The weight = 0 means it is off by default, but it might help you get more resolution
where you want it.  Try different values for the weight -- 10, 100, 1000.
See what happens to the mesh.  Let us know if it helps.

Cheers,
Bill






On Mar 1, 2013, at 8:59 AM, Zhao Guo wrote:

> Dear all,
> I am a new MESA user.I am trying to generate a model for some
> non-adiabatic pulsation studies.
> 
> The model profiles generated by the defualt example_astero (with a
> mesh_delta_coeff=0.4)in test_suite have ~1600 layers from center to
> surface,but they are too coarse in the surface hydrogen and helium
> ionization zones.
> My goal is to increase the resolution so that hydrogen and helium
> ionization zone,especially the He II ionization zone can be resolved.
> Is there a good way to do this?
> 
> I assume changing mesh_delta_coeff to a smaller value(eg. ~0.1) will
> increase the resolutin for the whole star.I looked through the '!mesh
> adjustment' in controls.defaults but didn't find any help.
> 
> Thank you very much!
> 
> best regards,
> Zhao
> 
> 
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