In this chapter we first consider steady radiation hydrodynamical winds in the nonrelativistic regime, focusing our attention on the topological nature of critical points. These radiatively-driven winds are supposed to operate in nova outbursts, neutron star winds, and black-hole ones. We next briefly mention radiation-dominated accretion flows onto a compact object. We also outline a line-driven wind model, which may work in stellar winds from hot stars, in accretion disk winds in cataclysmic variables, in broad absorption line quasars, and in ultra-fast outflows from active galactic nuclei. We finally show the self-similar treatment of the radiation hydrodynamical flows.