Fig. 2.
The results of sensitivity tests on a single unruptured MCA case. (a) The discretization scheme sensitivity tests showing aneurysm-averaged fKE and velocity magnitude for five combinations of first- and second- order discretization schemes. The stable (gray) and unstable regimes which were initially defined by the threshold of aneurysmal fKE of 10−4 m2/s2 (dashed line). Results showed that second-order temporal and spatial discretization schemes are necessary to capture flow fluctuations. (b) Grid-independence study showing convergence of aneurysm-averaged fKE and velocity magnitude between 2.2 × 106 and 4.7 × 106 elements. (c) Time step-independence study showing the aneurysm-averaged fKE and velocity magnitude with successive refinement of the CFL number. For simulations with both 2.2 × 106 and 4.7 × 106 elements, no appreciable change in fluctuation energy and velocity magnitude was found for a CFL number of 1. (d) The results of inflow rate sensitivity tests, where flow rate was varied in the physiologic range. Aneurysmal fKE increased with increasing inflow rates, but the case retained unstable flow characteristics.