  We study the granular segregation in a tapered rotating drum by means of
simulations. In this geometry, both radial and axial segregation appear, the
strength of which depends on the filling fraction. We study the effect of the
drum's tapering angle on the segregation speed and show that, coherently with
several recent studies, the axial segregation is due to the combined effect of
the radial segregation and the shape of the drum. We show that the axial
segregation behaves in a way analogous to the one found in chute flows, and
corresponds to previous theories for shallow gravity driven surface flows with
diffusion. By means of this analogy, we show that tapered drums could be the
simplest experimental set-up to obtain the free parameters of the theory.
