  Two families of models of rotating relativistic disks based on Taub-NUT and
Kerr metrics are constructed using the well-known "displace, cut and reflect"
method. We find that for disks built from a generic stationary axially
symmetric metric the "sound velocity", $(pressure/density)^{1/2}$, is equal to
the geometric mean of the prograde and retrograde geodesic circular velocities
of test particles moving on the disk. We also found that for generic disks we
can have zones with heat flow. For the two families of models studied the
boundaries that separate the zones with and without heat flow are not stable
against radial perturbations (ring formation).
