[CIG-LONG] Corner Flow Velocity unstable at initial condition

[Karen Paczkowski]

Hi,

I have been trying to write a benchmark code for a simple corner flow  
model using GALE.  For a 90 degree corner I have found that by adding  
a small velocity gradient near the corner and by using the analytic  
solution as boundary conditions the velocity field converges to the  
analytic solution.  However, this is only true of the velocity field  
at the 1st time step.  After that the numerical answer seems to go  
unstable, producing internal velocities a couple orders of magnitude  
higher than any of the boundary conditions.

Has anyone encountered anything like this?

What might be happening?


I have attached my .xml file and the File1, File2, File3 and File4  
files used as the input for the analytic solution boundary conditions.

The top BC is vx = 1 and vy =0, the left is vx = 0 and vy = -1, the  
boundary conditions for the right and bottom use the input files to  
give them the values of the analytic solution.  The velocity gradient  
in the top left corner spans the length of 10% of the box size along  
the top and left side.

I have also attached pictures of the velocity field at the 1st time  
step and then at the second time step.  The background color is  
velocity magnitude.

Thank you,
Karen

>
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