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In these proceedings we present recent efforts to understand the energeticsof magnetohydrodynamic (MHD) turbulence driven by the magneto-rotationalinstability (MRI). These studies are carried out in the local (shearing box)approximation using the Athena simulation code. Athena is a higher orderGodunov algorithm based on the piecewise parabolic method (PPM), the cornertransport upwind (CTU) integration algorithm, and the constrained transport(CT) algorithm for evolving the magnetic field. This algorithm is particularlysuited for these studies owing to the conservation properties of a Godunovscheme and the particular implementation of the shearing box source terms usedhere. We present a variety of calculations which may be compared directly topreviously published results and discuss them in some detail. The onlysignificant discrepancy found between the results presented here and in thepublished literature involves the turbulent heating rate. We observe thepresence of recurrent channel solutions in calculations involving a meanvertical magnetic field and the associated time lag between the energyinjection and thermalization rate. We also present the results of a shearingbox calculation which includes an optically thin radiative term with a coolingrate selected to match the turbulent heating rate. Some properties which wefind uniformly present in all of the calculations presented here arecompressible fluctuations, spiral waves and weak shocks. It is found that thesecompressible modes dominate the temporal fluctuations in the probabilitydistribution functions for most of the thermodynamic variables; only thespecific entropy is relatively immune to their effects.Comment: 14 pages, Conference Proceedings: "Magnetic Fields in the Universe:  from Laboratory and Stars to Primordial Structures

Energetics in MRI driven Turbulence