  Dry granular material flowing on rough inclines can experience a self-induced
Rayleigh-Taylor (RT) instability followed by the spontaneous emergence of
convection cells. For this to happen, particles are different in size and
density, the larger particles are the denser but still segregate toward the
surface. When the flow is, as usual, initially made of two layers, dense
particles above, a Rayleigh-Taylor instability develops during the flow. When
the flow is initially made of one homogeneous layer mixture, the granular
segregation leads to the formation of an unstable layer of large-dense
particles at the surface which subsequently destabilizes in a RT plume pattern.
The unstable density gradient has been only induced by the motion of the
granular matter. This self-induced Rayleigh-Taylor instability and the
two-layer RT instability are studied using two different methods, experiments
and simulations. At last, contrarily to the usual fluid behavior where the RT
instability relaxes into two superimposed stable layers of fluid, the granular
flow evolves to a pattern of alternated bands corresponing to recirculation
cells analogous to Rayleigh-B{\'e}nard convection cells where segregation
sustains the convective motion.

Soft Condensed Matter;Classical Physics;Geophysics