[aspect-devel] Boundary composition

[John Naliboff]

Hi Lev,

Initial composition would be the correct boundary choice for what you 
are trying to do.

One thing that may help is to use the discontinuous composition 
discretization option, if you have not tried it already.  This helps 
tracks compositional field boundaries more accurately through time and 
removes compositional field diffusion effects. Certainly helped with 
some of the models I am running.

Below is a section from a .prm file where I use this option.  FYI, you 
will want to use the development version of dealii (master branch from 
Github) if you use the discontinuous composition discretization option.  
The model will run with dealii version 8.4.1, but the development 
version helps reduce the memory requirements dramatically.

If this option helps, please let us know.

Cheers,
John

*************************************************
John Naliboff
Assistant Project Scientist, CIG
Earth & Planetary Sciences Dept., UC Davis
**

*# Use disccontinous composition bound preserving limiter*
*subsection Discretization*
*set Use discontinuous composition discretization = true*
*subsection Stabilization parameters*
*set Use limiter for discontinuous composition solution = true # apply 
the limiter to the DG solutions*
*set Global composition maximum = 1.0, 1.0, 1.0, 1.0*
*set Global composition minimum = 0.0, 0.0, 0.0, 0.0*
*end*
*end*



On 09/27/2016 01:09 PM, Lev Karatun wrote:
> Hi,
>
> I'm doing a lithospheric scale convergence model, imposing influx 
> (along the x axis) at the top half of the side walls (y=0, YMAX), and 
> outflux at the bottom half. Over the course of the simulation, the 
> lithosphere at the side of the model (the part that was injected) gets 
> progressively thinner. The vertical (z) and lateral (y) velocities are 
> set to zero at the boundary, but I noticed that a lateral flow is 
> still happening very close to the side wall, and my guess is that due 
> to the material mixing the outermost cells don't consist of 
> lithoshperic material anymore, but only of, let's say, 80% 
> lithospheric and 20% mantle. So the question is: is it possible to 
> manually restrict the incoming material to be of the same properties 
> as it was in the outer cells at the beginning of the simulation (as 
> opposed to the previous time step, which as fast as I understand is 
> defining the material right now -- correct me if I'm wrong). Also, I 
> was wondering if parameters in section Boundary composition model are 
> related to this? I tried setting Model name to "initial composition" 
> but it didn't seem to change anything.
>
> Thanks in advance.
>
> Best regards,
> Lev Karatun.
>
>
> _______________________________________________
> 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/20160928/25725b7e/attachment-0001.html>