  Numerical solutions for the integral curves of the velocity field
(streamlines), the density contours, and the accretion rate of a steady-state
flow of an ideal fluid with $p=K n^\gamma$ equation of state are presented. The
streamlines and velocity fields associated with a black hole and a rigid sphere
in a Reissner-Nordstr\"om-(anti) de Sitter spacetimes are studied in some
detail. For each case the fluid density is studied using contour lines. For
$\gamma \neq 2$, we found that the studied properties of the fluid are more
sensitive to variations of the electric charge and the cosmological constant.
Also, the accretion rate was found to increase or decrease when the
cosmological constant increases or decreases respectively.
