Accretion disks can be found around black holes of almost any size: from

galactic 1-10 solar mass black hole X-ray binaries to active galactic

nuclei with black holes the mass of 10^6 - 10^9 suns. Since

self-gravity of matter near the hole is often insignificant, the

hole's mass (in the absence of mass scales set by radiative processes)

is the only length scale in the problem and one can justifiably study

a whole class of objects simultaneously. I will present new simulation

results of 3D magnetohydrodynamic disks on a stationary curved background

using a recently developed 3D version of the energy-conserving HARM code.

Since the code captures all energy dissipated in 3D disks as heat

and does not assume an isentropic equation of state, our new calculations

represent the most accurate picture to-date of a disk's thermodynamics near a

black hole. In order to verify the validity of the standard radiative

efficient models by Novikov and Thorne, we implement a cooling function

to approximate losses from prompt emission. We find that the

disk's local luminosity profile closely follows the Novikov-Thorne model

up to the radius of the innermost stable circular orbit (ISCO).

Within the ISCO we find the luminosity increases steadily to the

horizon with no significant deviation from the average power-law profile.

Also, I will show comparisons between the cooled run and an otherwise

equivalent uncooled run; these comparisons are the first to show how

GRMHD disks change with disk thickness. If time permits,

I will also present work on modeling the sub-millimeter emission from

plasma circling the supermassive black hole at the center of

our galaxy, Sgr A*.