[aspect-devel] Melting and a thrid composition

[Juliane Dannberg]

Hi Juan,

great to hear that you're using the melt migration!
As melt migration models are so complex and have so many different 
parameters (including all of the additional material properties for the 
melt, and the melting parametrization), we couldn't add all of the 
different options for material properties to these material models. 
They're more meant as examples for how to write such a material model.

So depending on the application you want to use this for, you will 
probably have to modify either the 'melt simple' or the 'melt global' 
model, whichever is closer to what you have in mind (Section 6 of the 
ASPECT manual contains a lot of information on ASPECT's plugin structure 
and how to extend the code). The simplest way would probably be to add a 
'Compositional viscosity prefactor' parameter in the same way this is 
done for example in the 'simple' material model (so you can essentially 
just copy that code over to the new, modified material model you would 
make). Keep in mind though that this prefactor always applies to the 
first compositional field, so you would have to modify the code if you 
want the prefactor to be applied to a different field or more than one 
field.

In general, there might also be other things you will want to modify in 
the material model depending on your application. In particular, the 
melting parametrization e.g. in the 'melt simple' model is based on data 
for melting at mid-ocean ridges. So if you have a new field with a 
different chemical composition in your model, or if you're just looking 
at a different setting, you may have to think about how that influences 
your melting model.

Hope that helps!
Juliane


On 05/30/2018 07:31 AM, Juan Rodriguez-Gonzalez wrote:
> Hello,
> I am playing around with the Melt migration in a 2D mantle convection 
> coockbook and I was trying to add a compositional field that has an 
> increased viscosity. I could add a third composition (in addition to 
> peridotite and porosity), but I am not sure how I could change its 
> properties. Provided that there is no 'Compositional viscosity 
> prefactor' in the material models 'melt simple' and 'melt global', is 
> there some way to approach this?
>
> Thanks,
> Juan
>
> _________________________________________
> Dr. Juan Rodriguez-Gonzalez
> Department of Earth Sciences
> Durham University
> Science Labs
> Durham DH1 3LE
> Tel: +44 191 33 42357
> juan.rodriguez-gonzalez at durham.ac.uk 
> <mailto:juan.rodriguez-gonzalez at durham.ac.uk>
> https://www.researchgate.net/profile/Juan_Rodriguez-Gonzalez 
> <https://www.researchgate.net/profile/Juan_Rodriguez-Gonzalez>
> https://scholar.google.com/citations?user=0oai9e0AAAAJ&hl=en 
> <https://scholar.google.com/citations?user=0oai9e0AAAAJ&hl=en>
>
>
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----------------------------------------------------------------------
Juliane Dannberg
Project Scientist, UC Davis
jdannberg.github.io <https://jdannberg.github.io/>


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