V.V. Zhuravlev Lomonosov Moscow State University, Shternberg State Astronomical Institute, Universitetskii prosp. 13, Moscow, 119889, Russian Federation
The purpose of this paper is to present not a literature review but rather a description, as detailed and consistent as possible, of two analytical models of disk accretion onto a rotating black hole: a standard relativistic disk and a twisted relativistic disk. Even though one of these models is older than the other, both are of topical current interest for black hole studies. The way the exposition is presented, the reader with only a limited knowledge of general relativity and relativistic hydrodynamics can — with little or no use of additional sources — gain good insight into many technical details not present in the original papers.