Structure and Evolution of an Isothermal Thin Accretion DiskAround a Black Hole

In this paper, we construct an isothermal thin accretion disk model around a black hole for which the vertical mass density is expressed as ρ = ρ₀e^-z2/2z₀2. The hydrostatic equilibrium equations of the model disk and their difference forms are derived. We solve the basic balance equations by numerical method. According to the calculation results, the structure and evolution of model disk are discussed.