[CIG-LONG] CIG-LONG Digest, Vol 51, Issue 2 Alleviating pressure singularity in corner-flow mantle-wedge subduction zone model

[Walter Landry]

Karen Paczkowski <karen.paczkowski at yale.edu> wrote:
> Hi Walter,
> 
> Thank you for the advice and input file.  I am having trouble using
> the gradient region to alleviate the negative pressure singularity
> with velocities that diverge from the corner.

If the velocities diverge from the corner, then a pressure singularity
is expected.  Diverging velocities are not allowed by the continuity
equation.  The only reason that Gale finds a solution at all is
because of the artificial compressibility.

> Specifically, if the left side has a velocity of vy = -1 and vx = 0
> and then the top is either fixed with vx=vy=0 or extending vx = 1 and
> vy = 0 a source like flow forms radiating out of the corner.

To get a solution, there has to be as much going into the corner as
going out.  In this case, it could be 

  left side: vy=-1, vx=0
  top side:  vy=0,  vx=-1

The parameters for the corner shape flow has to changed to be
compatible with this.

Cheers,
Walter Landry
walter at geodynamics.org