Clumpy accretion onto black holes. I. Clumpy-ADAF structure and
  radiation
  In this paper, we investigate the dynamics of clumps embedded in and confined
by the advection-dominated accretion flows (ADAF), in which collisions among
the clumps are neglected. We start from the collisionless Boltzmann equation
and assume that interaction between the clumps and the ADAF is responsible for
transporting angular momentum of clumps outward. The inner edge of the
clumpy-ADAF is set to be the tidal radius of the clumps. We consider strong and
weak coupling cases, in which the averaged properties of clumps follow the ADAF
dynamics and mainly determined by the black hole potential, respectively. We
get the analytical solution of the dynamics of clumps for the two cases. The
velocity dispersion of clumps is one magnitude higher than the ADAF for the
strong coupling case. For the weak coupling case, we find that the mean radial
velocity of clumps is linearly proportional to the coefficient of the drag
force. We show that the tidally disrupted clumps would lead to accumulation of
the debris to form a debris disk in the Shakura-Sunyaev regime. The entire hot
ADAF will be efficiently cooled down by photons from the debris disk, giving
rise to collapse of the ADAF and quench the clumpy accretion. Subsequently,
evaporation of the collapsed ADAF drives resuscitate of a new clumpy-ADAF,
resulting in an oscillation of the global clumpy-ADAF. Applications of the
present model are briefly discussed to X-ray binaries, ionization nuclear
emission regions (LINERs) and BL Lac objects.
