  We present analogue models for the Schwarzschild and Reissner-Nordstr\"om
(RN) spacetimes based on unidirectional hydrodynamic flows. We show that, with
appropriate coordinate transformations, sound waves in a moving fluid propagate
as scalar fields at the equatorial sections of Schwarzschild and RN black
holes. The coordinate associated with the direction of the flow plays the role
of the radial coordinate in standard Schwarzschild/RN coordinates, while the
transversal spatial coordinate is related to the angular coordinate on each
equatorial slice. The magnitude of the flow velocity is related to the mass and
charge of the analogue black hole. Physical quantities like pressure and
density remain finite at the analogue horizon, thereby resulting in sound waves
that are well defined almost everywhere, except possibly at the analogue black
hole singularity.
