are presented as a step beyond the single irradiated annuli studied by Tuchman et al. (1990) and Mineshige et al. (1990b) and as a step toward the ultimate solution of time-dependent irradiated disks. They should not be viewed as full disk models, but as collections of coupled annuli that, nevertheless, give some qualitative insight into the physics of irradiated, time-dependent accretion disks.

Model Parameters
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We choose a 4$M_{\odot}$ black hole with a companion of 0.27$M_{\odot}$ as being representative of A0620–00 (Marsh et al. 1994 and references therein). This choice, with the observed orbital period of 7.75 hr, gives the following disk model parameters: $R_{\rm in}$ = $3.6{\times}10^6$ cm, binary separation $2.24{\times}10^{11}$ cm, Roche lobe radius of the primary system $1.83{\times}10^{11}$cm and the disk radius $10^{11}$cm (Frank et al. 1992; Paczy[ń]{}ski 1977). Both the inner and outer boundaries of the disk are held fixed. We tested a range of values of $R_{\rm out}$, and found that the qualitative behavior is similar for outer-disk radii in the range $5{\times}10^{10}$cm $<$ $R_{\rm out}$ $\lta$ $1.3{\times}10^{11}$cm, the tidal radius of the disk. We choose the mass-transfer rate from the companion star to be ${\dot M}_{\rm T}$ = $3.16{\times}10^{16}$g s$^{-1}$. This is larger than 