[aspect-devel] Question on Thermal Viscosity thresholds

[Lev Karatun]

Hi Felippe,

I didn't write the plugin, but I'll try to give you an answer based on
looking at the code and the manual.
As long as temperature range is continuous, I don't think there will be any
discontinuities in the viscosity. Thermal prefactors (which are set using
the "Maximum thermal prefactor" and "Minimum thermal prefactor" parameters)
are just limiters, they don't add any non-linearity into the calculations.
If you make the range too wide, the solver might have problems converging,
but other than that it should be fine. Is this what you were asking?

As a side note, a new version of the manual is generated every day, so page
numbers aren't too helpful to locate the part you're referring to. Maybe
you could quote it instead or specify a section title?

Best regards,
Lev Karatun.

2018-04-25 16:50 GMT-04:00 FELIPE ORELLANA ROVIROSA <f_orellana at berkeley.edu
>:

>
>  Hi,
>
>       Hope you guys are having a nice day.
>
>        I am crafting and trying different models on a 3D convecting
> system, and considering Temperature-dependent viscosity among other things.
>
>        For the material model 'simple', the viscosity depends on
> temperature as a negative exponential (a classic), but some
> thresholds/bounds are imposed on it.
>
>        According to Aspect manual 1.5.0, page 289; if the exponential is
> out of the bounds [ 0.01 , 100 ], that part of the viscosity will assume
> the user-defined threshold values given by (Tau min, Tau max). Later the
> amplitude will be given by the scaling constant eta0.
>
>        But, if a user chooses values for {Tau min, Tau max} different than
> {0.01 , 100}, then discontinuities in viscosity will be produced over the
> temperature range.
>
>        The question is the following: are those limits 10^-2 < x < 10^2
> only a handbook example?, or will those limits assume the user-specified
> values of Taumin, Taumax?
>
> warm regards,
> Felipe
>
>
>
>
>
>
> _______________________________________________
> Aspect-devel mailing list
> Aspect-devel at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/aspect-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.geodynamics.org/pipermail/aspect-devel/attachments/20180426/479f0131/attachment-0001.html>