The dynamics of twisted disc formed after the tidal disruption of a star
  by a rotating black hole
  We consider misaligned accretion discs formed after tidal disruption events
occurring when a star encounters a supermassive rotating black hole. We use the
linear theory of warped accretion discs to find the disc shape when the stream
produced by the disrupted star provides a source of mass and angular momentum
that is misaligned with the black hole. The evolution of the surface density
and aspect ratio is found from a one dimensional vertically averaged model.
  We extend previous work which assumed a quasi-stationary disc to allow
unrestricted dynamical propagation of disc tilt and twist through time
dependent backgrounds. We consider a smaller value of the viscosity parameter,
$\alpha =0.01,$ finding the dynamics varies significantly.
  At early times the disc inclination is found to be nearly uniform at small
radii where the aspect ratio is large. However, since torques arise from the
Lense-Thirring effect and the stream there is non uniform precession. We
propose a simple model for this requiring only the background surface density
and aspect ratio.
  At these times the $\alpha \sim 0.01$ disc exhibits a new feature. An
inclined hot inner region joins an outer low inclination cool region via a thin
transition front propagating outwards with a speed exceeding that of bending
waves in the cool region. These waves accumulate where the propagation speeds
match producing an inclination spike separating inner and outer discs. At late
times a sequence of quasi-stationary configurations approximates disc shapes at
small radii. We discuss observational implications of our results.
