  Time evolution of an advection-dominated accretion flow is explored in terms
of relativistic fluid equations. An axially symmetric, vertically averaged mean
flow is constructed and then perturbed. An axisymmetric pattern is followed as
it propagates in the form of a wave towards the horizon of a rotating (Kerr)
black hole. Several assumptions are relaxed in comparison with previous works
(Manmoto et al. 1996).
