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We study the effect of irradiation in accretion disks around black hole X-ray novae. Two types of irradiation are considered: direct irradiation from the inner disk and indirect irradiation reflected by a corona or chromosphere. The irradiation is a function of the time-dependent mass accretion rate and location in the disk and affects the rise, peak luminosity, and decay time of the burst. We include the dynamic effects of the evolution of the disk height profile as the disk is irradiated. As a result, irradiation of intermediate portions of the disk cause them to swell and shadow the outer portion of the disk from direct irradiation. Some time after primary maximum, 50 to 100 days depending on parameters, inner portions of the disk shrink in height, reducing the shadowing of the outer portion of the disk thus exposing them to the direct irradiation. This produces secondary optical flares similar to those observed in A0620-00 and Nova Muscae. Modulation of the mass flow through the disk may also yield a small increase of the soft X-ray flux at about the same time. These models do not require an external source such as a suddenly enhanced mass transfer rate from the companion star to explain the secondary flare. We discuss the implications of these results to optical, X-ray and gamma-ray observations.
