Hi, My apologies if this is a dumb question.
I'm playing with the gowdy.par file provided in the Einstein toolkit (Cactus/par/arXiv:1111.3344/cosmology) and I'm having trouble enforcing the periodic boundary conditions. The original gowdy.par file sets up a grid like this INFO (CartGrid3D): Grid Spacings: INFO (CartGrid3D): dx=>2.0000000e-02 dy=>2.0000000e-02 dz=>2.0000000e-02 INFO (CartGrid3D): Computational Coordinates: INFO (CartGrid3D): x=>[-0.550, 0.550] y=>[-0.550, 0.550] z=>[-0.550, 0.550] INFO (CartGrid3D): Indices of Physical Coordinates: INFO (CartGrid3D): x=>[0,55] y=>[0,55] z=>[0,55] But that is a huge overkill -- the gowdy metric has symmetries in the x,y directions. So I modified gowdy.par to use CoordBase::xmin = -0.0390625 CoordBase::ymin = -0.0390625 CoordBase::xmax = 0.0390625 CoordBase::ymax = 0.0390625 CoordBase::dx = 0.0078125 CoordBase::dy = 0.0078125 CoordBase::zmin = -0.5078125 CoordBase::zmax = +0.5078125 CoordBase::dz = 0.0078125 and this created the following grid INFO (CartGrid3D): Grid Spacings: INFO (CartGrid3D): dx=>7.8125000e-03 dy=>7.8125000e-03 dz=>7.8125000e-03 INFO (CartGrid3D): Computational Coordinates: INFO (CartGrid3D): x=>[-0.055, 0.055] y=>[-0.055, 0.055] z=>[-0.523, 0.523] INFO (CartGrid3D): Indices of Physical Coordinates: INFO (CartGrid3D): x=>[0,14] y=>[0,14] z=>[0,134] The problem now is that after just one time step the extrinsic curvatures are not periodic -- there are sharp jumps in Kzz at z=+/-0.5. The original gowdy file does not *appear* to have this problem (though with 56 grid points the jumps in Kzz will, if they exist, be much smaller than for just 15 points in my case). Am I doing something silly here? I've made no other changes to the gowdy.par file (other than to comment out the HDF5 stuff). I'm running this through the Einstein Toolkit/McLachlan on a single processor Mac. Any suggestions would be most welcome, thanks Cheers, Leo _______________________________________________ Users mailing list [email protected] http://cactuscode.org/mailman/listinfo/users
