2D Transonic Hydrodynamics in General Relativity
  The goal of my lecture is to present the introduction into the hydrodynamical version of the Grad-Shafranov equation. Although not so well-known as the full MHD one, it allows us to clarify the nontrivial structure of the Grad-Shafranov approach as well as to discuss the simplest version of the 3+1-split language -- the most convenient one for the description of the ideal flows in the vicinity of a rotating black hole. 
V.S.Beskin