Upper panel: 2D graph of the density of a converged model of a circumstellar viscous outflowing disk of a critically rotating B0-type star in the very inner region up to 5 stellar radii, corresponding to the disk mass-loss rate Ṁ = 10⁻⁸ M_⊙ yr⁻¹, with the constant viscosity parameter α = α₀ = 0.1. The sonic point radius is in this case approximately 2.5 × 10⁴ R_eq and the density profile is relatively smooth. The contours mark the density values (from lower to higher) 2.5 × 10⁻⁸, 5 × 10⁻⁸, 10⁻⁷, 1.5 × 10⁻⁷, 2 × 10⁻⁷ [kg m ⁻³], and so on, with a constant increment of 0.5 × 10⁻⁷ kg m⁻³. Lower panel:same graph, but with the viscosity coefficient α = α₀ = 1. The density profile shows significant roughly periodic waves that occur in the case of a viscosity parameter α ≳ 0.5. The contours mark the density levels (from lower to higher) 2.5 × 10⁻⁸, 5 × 10⁻⁸, 7.5 × 10⁻⁸ and 10⁻⁷ [kg m ⁻³].