  Most Computational Fluid Dynamics (CFD) studies of hemodynamics in
intracranial aneurysms are based on the assumption of laminar flow due to a
relatively low (below 500) parent artery Reynolds number. A few studies have
recently demonstrated the occurrence of transitional flow in aneurysms, but
these studies employed special finite element schemes tailored to capture
transitional nature of flow. In this study we investigate the occurrence of
transition using a standard Lattice Boltzmann method (LBM). The LBM is used
because of its computational efficiency, which in the present study allowed us
to perform simulations at a higher resolution than has been done in the context
of aneurysms before. The high space-time resolutions of 8{\mu}m and 0.11 {\mu}s
resulted in nearly one billion cells and 9 million time steps per second and
allowed us to quantify the turbulent kinetic energy at resolutions below the
Kolmogorov scales. We perform an in-depth space and time refinement study on 2
aneurysms; one was previously reported laminar, while the other was reported
transitional. Furthermore, we investigate the critical Reynolds number at which
the flow transitions in aneurysms under time constant inflow conditions.
