[aspect-devel] Implementing another solution variable

[Jonathan Perry-Houts]

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Thanks Wolfgang,

I'll keep an eye on the git repository for this advection field
modification and see what I can do with it. Sounds like a good idea!

Cheers,
Jonathan

On 05/20/2014 06:19 AM, Wolfgang Bangerth wrote:
> 
> Hi Jonathan,
> 
>> To implement this Keller melt transport model, I'm adding
>> another (optional) solution variable in Aspect that will
>> eventually be solved along with velocity and pressure in the
>> stokes step. Does it matter in which order the FESystem
>> components are organized? ie, should I put porosity before
>> temperature, and then adjust the introspection indices of
>> temperature and compositions and probably a dozen other hard
>> coded spots in in the code, or can I tack the new solution
>> component on to the end and use blocks to access that chunk of
>> the matrix?
> 
> Ultimately, it shouldn't matter which way it's done as long as 
> introspection describes it correctly. There may be a few places
> left in the code that hard code block numbers instead of using
> introspection, but these should be changed anyway.
> 
> That said, if your field is just a scalar one (such as the
> porosity) then please hold on with these modifications. At the
> workshop this week, we've come up with a plan to make this all a
> bit simpler. Adding new fields everytime anyone wants to extend the
> model is not a scalable alternative. Rather, we'd just want to put
> these fields into the compositional fields and let the existing
> machinery deal with them. One would then just have to attach a
> name/kind to each of these fields. Give us a week to get this
> done.
> 
> 
>> Also, since I'll be modifying the system matrix, I'd like to be
>> able to use the direct solver (which is still a work in progress
>> at this time, although it looks like Timo's been making good
>> headway on it). Anyway, that means this new variable will need to
>> be able to be (optionally) part of the same "block" as velocity
>> and pressure. Is it possible for example to make block 0 contain
>> components 0-dim and dim+2+n_compositional_fields?
> 
> Not this way. But why do you want to solve the additional Stokes
> block jointly with your new field? Wouldn't it be better to solve
> the separately, just like we currently do with temperature and the
> Stokes variables?
> 
> Best W.
> 
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