[CIG-LONG] Alleviating pressure singularity in corner-flow mantle-wedge subduction zone model

[Walter Landry]

Karen Paczkowski <karen.paczkowski at yale.edu> wrote:
> Hi,
> 
> I am trying to write a simple corner-flow mantle-wedge subduction zone  
> model using Gale.  Since, in the corner of the wedge the velocity  
> abruptly changes from v=vslab along the slab to v=0 along the  
> overriding plate a pressure singularity develops in the corner of the  
> wedge.
> 
> I was wondering if anyone else has encountered this issue and what  
> they did to alleviate the pressure singularity in the corner?
> 
> I have tried adding a small shape along the slab-mantle interface  
> right near the corner that has a velocity with a gradient going from  
> v=0 to v=slab over a couple of resolution points.  This mainly seems  
> to move my pressure singularity around, but not elimiate it.
> 
> Any advice people have on alleviating the pressure singularity in a  
> corner-flow subduction model would be greatly appreciated.

Have you tried fixing the velocity within the box near the corner?
Specifically, you can try using a MeshShapeVC on a region near the corner.
This should remove the pressure singularity, because you are no longer
solving near the singular point.

To illustrate, I am attaching two input files.  There are still some
issues at the edge of the MeshShapeVC because the matching is not
exact, but the error is much smaller.  Without the fix, the pressure
goes up to 213.  With the fix, the max pressure is about 7.

Cheers,
Walter Landry
walter at geodynamics.org
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