  We study the long-term evolution of non-radiative geometrically thick
($H/R\approx 0.5$) accretion flows using 3D global ideal MHD simulations and a
pseudo-Newtonian gravity. We find that resolving the scale height with 42 grid
points is adequate to obtain convergence with the product of quality factors
$\langle \langle Q_{\theta} \rangle \rangle \langle \langle Q_{\phi} \rangle
\rangle \geq 300$ and magnetic tilt angle $\theta_B \sim
13^{\circ}-14^{\circ}$. Like previous global isothermal thin disk simulations,
we find stronger mean magnetic fields for the restricted azimuthal domains.
Imposing periodic boundary conditions with the azimuthal extent smaller than
$2\pi$ make the turbulent field at low $m$ appear as a mean field in the runs
with smaller azimuthal extent. But unlike previous works, we do not find a
monotonic trend in turbulence with the azimuthal extent. We conclude that the
minimum azimuthal extent should be $\geq \pi/2$ to capture the flow structure,
but a full $2 \pi$ extent is necessary to study the dynamo. We find an
intermittent dynamo cycle, with $\alpha$-quenching playing an important role in
the nonlinear saturated state. Unlike previous local studies, we find almost
similar values of kinetic and magnetic $\alpha$-s, giving rise to an irregular
distribution of dynamo-$\alpha$. The effects of dynamical quenching are shown
explicitly for the first time in global simulations of accretion flows.
