I also need to know this - that is, to get PV-displayed, multiblock data out of ParaView and into Python as a flat array. Have you tried the Python interface package “paraview?” One of the problems I’m having simply outputting data from ParaView is that it gives data files (CSV) listed in block format, and also doesn’t seem to output the correct number of points, even when requesting cell-center data. My simulation is 48 x 126 = 6,048 cells, but ParaView always puts out 12,283 data points, even when requesting cell center data - so that’s confusing.
Has anyone tried the Python package “paraview?” Does it work for extracting data? I think this package can also access data slices that OP needs…