We consider the effects of advection and radial gradients of pressure and radial drift velocity on the structure of optically thick accretion disks .
We concentrate our efforts on highly viscous disks , \alpha = 1.0 , with large accretion rates .
Contrary to disk models neglecting advection , we find that continuous solutions extending from the outer disk regions to the inner edge exist for all accretion rates we have considered .
We show that the sonic point moves outward with increasing accretion rate , and that in the innermost disk region advection acts as a heating process that may even dominate over dissipative heating .
Despite the importance of advection on it ’ s structure , the disk remains geometrically thin .