  We have performed three-dimensional magneto-hydrodynamical simulations of
stellar accretion disks, using the PLUTO code, and studied the accretion of gas
onto a Jupiter-mass planet and the structure of the circumplanetary gas flow
after opening a gap in the disk. We compare our results with simulations of
laminar, yet viscous disks with different levels of an $\alpha$-type viscosity.
In all cases, we find that the accretion flow across the surface of the Hill
sphere of the planet is not spherically or azimuthally symmetric, and is
predominantly restricted to the mid-plane region of the disk. Even in the
turbulent case, we find no significant vertical flow of mass into the Hill
sphere. The outer parts of the circumplanetary disk are shown to rotate
significantly below Keplerian speed, independent of viscosity, while the
circumplanetary disk density (therefore the angular momentum) increases with
viscosity. For a simulation of a magnetized turbulent disk, where the global
averaged alpha stress is $\alpha_{MHD}=10^{-3}$, we find the accretion rate
onto the planet to be $\dot{M}\approx 2\times10^{-6}M_{J}yr^{-1}$ for a gap
surface density of $12 g cm^{-2}$. This is about a third of the accretion rate
obtained in a laminar viscous simulation with equivalent $\alpha$ parameter.
