[Users] evolving flat boundary conditions

[Ryn Grutkoski]

Hello,

I am trying to do a cosmology simulation project using Cactus. For this
project, I'm evolving an expanding homogeneous fluid in a box (FLRW
spacetime), and I would like to use flat boundary conditions. I've attached
the par file I am currently using. However, when I run this, the boundary
cells do not seem to update at each time step to match the current value of
the grid cells on the edge, as seen in this plot of the second time step
output:
[image: image.png]

Is there a way to make the the boundary cells be updated at each time step
according to the evolution of the edge of the grid?

Thank you,
Ryn

-- 
Ryn Grutkoski
*they/them/theirs*
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