Hi all, I have a question which is kind of a yt question and kind of an enzo question, so first off, my apologies to the non-enzo users. I have something that quite clearly appears to be a boundary value problem on a non-periodic boundary condition. My first method of attack is to load the (single) root grid data object with its ghost zones: pf = load(data) gz = pf.h.grids[0].retrieve_ghost_zones(2,'y-velocity') However, when I do this on a sample I believe not to have the bug, it appears that yt is loading periodic boundary conditions in the non-periodic direction: the first ghost zone on the lower y boundary is exactly equal to the second-to-top active zone, and the second lower y ghost zone exactly equals the top active zone. More concretely, gz['y-velocity'][:,0,2] always equals gz['y-velocity'][:,-4,2] and gz['y-velocity'][:,1,2] always equals gz['y-velocity'][:,-3,2] This is very clear in the (2D) case at hand, since the velocity field is a large gradient in the y-direction. Is it possible that enzo is not outputting its ghost zones, and yt is simply filling using a periodic method? Or does enzo always output ghost zones, and this is simply a manifestation of my bug? I realize this is not a very clear question, but I'm a bit confused myself. thanks, j