[aspect-devel] mesh refinement strategy question

[Magali Billen]

Hello,

I am starting a project for subduction modeling in Aspect and I have a 	question about how certain mesh refinement strategies work together. Specifically, I need to define a “proto-slab” based on temperature,
 which is needed to start the subduction process. However, once the slab starts sinking its location in the model domain depends on the dynamics and it can move 1000s of kilometers from its starting location.  

So, I have first set this up using the  Strategy = minimum refinement function (see below for the 
full subsection definition). And, I can get a nice looking initial slab (see below).  However, after the initialization,
I would like the mesh refinement to depend on things like the temperature, (and later composition, and strain-rate).  It does not work to just use Strategy = temperature, because this just refines on the temperature field defined on the coarsest mesh (see picture).  

So, what is not clear to me is whether there is a way to use one Strategy during the initial adaptive refinement
and a different (set) of criteria after that point, or to combine them such that the minimum refinement function 
is no longer have much impact after the first step.

Has anyone else had a problem like this?  Any ideas?  
Instead of thinking about refining, should I start with a really fine mesh everywhere and then use the 
Strategy = temperature to coarsen the mesh where refinement isn’t needed. It doesn’t seem like it set up
to work that way?

- Magali
Here’s the prm file for the nice looking slab using the function to refine based on location:


Here’s just the mesh  refinement section:

subsection Mesh refinement
  set Initial global refinement                = 4
  set Minimum refinement level                 = 4
  set Initial adaptive refinement              = 5
  set Time steps between mesh refinement       = 1
  set Strategy = minimum refinement function
  subsection Minimum refinement function
    set Coordinate system   = cartesian
    set Variable names      = x,y
    set Function constants = YMAX=1e6,LITH=1.5e5,SM=2.5e5,XTR=2.2e6,RC=4e5
    set Function expression = if( (YMAX-y<=LITH)||((YMAX-y<=SM)&&(x<=XTR+3*RC)&&(x>=XTR-0.5*RC)),9,0)
  end
end

And, here are some screen-shots

Full domain




Zoom-in on slab 



This is what happens if I just use Strategy = temperature 


And if I combine them  (this is just the 0th time-step), I need to set up some other things before
I can run forward in time.


____________________________________________________________
Professor of Geophysics 
Earth & Planetary Sciences Dept., UC Davis
Davis, CA 95616
2129 Earth & Physical Sciences Bldg.
Office Phone: (530) 752-4169
http://magalibillen.faculty.ucdavis.edu

Currently on Sabbatical at Munich University (LMU)
Department of Geophysics (PST + 9 hr)

Avoid implicit bias - check before you submit: 
http://www.tomforth.co.uk/genderbias/
___________________________________________________________

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