  We explore models of hard-rod fluids with a finite number of allowed
orientations, and construct their bulk phase diagrams within Onsager's second
virial theory. For a one-component fluid, we show that the discretization of
the orientations leads to the existence of an artificial (almost) perfectly
aligned nematic phase, which coexists with the (physical) nematic phase if the
number of orientations is sufficiently large, or with the isotropic phase if
the number of orientations is small. Its appearance correlates with the
accuracy of sampling the nematic orientation distribution within its typical
opening angle. For a binary mixture this artificial phase also exists, and a
much larger number of orientations is required to shift it to such high
densities that it does not interfere with the physical part of the phase
diagram.
